Meteor Showers of Comet C/1964 N1 (Ikeya) L

A&A 616, A162 (2018) https://doi.org/10.1051/0004-6361/201832829 Astronomy & © ESO 2018 Astrophysics

Meteor showers of comet C/1964 N1 (Ikeya) L. Neslušan1 and M. Hajduková Jr.2

1 Astronomical Institute, Slovak Academy of Science, 05960 Tatranská Lomnica, Slovakia e-mail: [email protected] 2 Astronomical Institute, Slovak Academy of Science, Dúbravská cesta 9, 84504 Bratislava, Slovakia e-mail: [email protected]

Received 14 February 2018 / Accepted 23 May 2018

ABSTRACT

Aims. We intend to map the meteor complex of the long-period comet C/1964 N1 (Ikeya), which is a proposed parent body of the July ξ-Arietids, the meteor shower 533 in the IAU MDC list. Methods. For five perihelion passages of the parent comet in the past, we modeled the associated theoretical stream, its parts, consisting of 10 000 test particles each, and followed the dynamical evolution of these parts up to the present. We performed several simulations of the evolution, with various strengths of the Poynting–Robertson effect. At the end of each simulation, we analyzed the mean orbital characteristics of the particles that approached Earth orbit and thus created one or several showers. The showers were compared with their observed counterparts as separated from photographic and several video databases when the separation was successful. Results. The modeled stream of C/1964 N1 typically approaches Earth orbit in four filaments that correspond to four showers. Their radiant areas are close to the apex of Earth’s motion around the Sun. We confirm the generic relationship between the studied parent comet and the July ξ-Arietids. The comet also seems to be the parent of the -Geminids, shower 23, and we suspect a relationship between the comet and the ξ-Geminids, shower 718, although the relationship is rather uncertain. The real counterparts of three of the predicted showers were selected in the CAMS and SonotaCo databases. However, these real showers are diffuse, with relatively few members, and determination of their characteristics is therefore uncertain; the showers were separated into more than one single “modification”. Confirmation of their existence will have to await considerably more numerous data.

Key words. comets: individual: C/1964 N1 – meteorites, meteors, meteoroids

1. Introduction also known to produce meteoroid streams, for example, C/1861 G1 (Thatcher) with P = 415 yr. This is the parent body of the Periodic comets are expected to release small particles, mete- April Lyrids, shower 6 (Porubcanˇ et al. 1992; Arter & Williams oroids, from their nuclei. Since the escape velocity at release 1997; Porubcanˇ & Kornoš 2008; Kornoš et al. 2015). C/1917 F1 is negligible in comparison to the heliocentric velocity of the (Mellish) with P = 145 yr is the parent body of the Decem- comet, the orbits of the meteoroids do not initially differ much ber Monocerotids, shower 19 and, probably also of the April from the orbit of the comet. The meteoroids thus orbit the Sun in ρ-Cygnids, shower 348 (Ohtsuka 1989; Lindblad & Olsson-Steel a corridor they share with their parent. Nevertheless, the gravita- 1990; Hasegawa 1999; Vereš et al. 2011; Neslušan & Hajduková tional perturbations of planets and non-gravitational effects can 2014; Hajduková et al. 2015). C/1979 Y1 (Bradfield) with P = later move these meteoroids to some alternative orbital corridors. 305 yr is the parent body of the July Pegasids, shower 175 The spatial structure of the meteoroid stream becomes filamen- (Jenniskens 2006; Ueda 2012; Hajduková & Neslušan 2017). We tary, and the stream particles can collide with our planet in more also refer to the showers by their number in the IAU MDC list1 than a single arc of its orbit. (Jopek & Kanuchováˇ 2014) to give a unique identification. The structure of the stream that occurs as a result of the Comet C/1964 N1 has an orbital period equal to 391 yr dynamical evolution of the stream particles can be traced by and moves in a low-inclined but retrograde orbit; therefore, modeling the stream and its orbital evolution. In this paper, we the expected geocentric velocity of the associated meteors is model the potential stream of long-period comet C/1964 N1 very high. The meteoroids from the comet, if they are actually (Ikeya) in this way. The streams of long-period comets have released, are expected to exhibit an intensive light effect when not been modeled as often as streams associated with short- colliding with the Earth’s atmosphere, which means that the period parent bodies, such as comets 96P/Machholz (McIntosh meteors should be easily detected when they occur on the night 1990; Kanuchováˇ & Neslušan 2007; Babadzhanov et al. 2008; sky. Neslušan et al. 2013b; Abedin et al. 2018) or 12P/Pons-Brooks According to recent work by Šegon et al.(2017), comet (Tomko 2015; Tomko & Neslušan 2016), or asteroids such as C/1964 N1 is the parent body of the July ξ-Arietids, shower 3200 Phaethon (Babadzhanov 1994; Beech 2002; Ryabova 2007, 533. The authors modeled the streams of several parent bodies 2008; de León et al. 2010; Jakubík & Neslušan 2015; Ryabova & using the method developed by Vaubaillon et al.(2005); see also Rendtel 2018) or 196 256 (2003 EH1; Babadzhanov et al. 2008, Jenniskens & Vaubaillon(2008). 2017; Neslušan et al. 2013a; Kasuga & Jewitt 2015; Abedin et al. 2015). Comets with an orbital period, P, of several centuries are 1 https://www.ta3.sk/IAUC22DB/MDC2007/

Article published by EDP Sciences A162, page 1 of8 A&A 616, A162 (2018)

Consistent with several previous papers (e.g., Neslušan et al. To identify a predicted shower with its potential counterpart 2013b), we use the words “complex” and “stream” as synonyms in a given database, we attempted to separate the shower on the referring to the whole structure of meteoroids released from the basis of the predicted mean orbit from the database using the parent body. The complex often consists of several “filaments”. so-called break-point method (Neslušan et al. 1995, 2013c). In If the particles of a filament hit Earth, they can cause a meteor this method, the dependence of the number of selected meteors “shower” corresponding to the filament. of a shower on the limiting value of the Southworth–Hawkins (Southworth & Hawkins 1963) D discriminant, Dlim, is ana- 2. Orbit of the parent comet lyzed. If a shower is present in the set, then the dependence N = N(Dlim) has a convex behavior with a constant or almost In our study, we consider the orbit of comet C/1964 N1 with constant part: a plateau. The break point is a critical point the orbital elements published in the JPL small-body browser N(D ) behavior, giving the most suitable limiting value for the 2 lim (Giorgini et al. 1996) . This orbit, referred to as at epoch D discriminant to select the densest part of a particular shower 1964 July 24.0 (JDT = 2438600.5), has these elements: from the near orbital phase space. A similar method for isolating q = 0.821752 au, e = 0.984643, a = 53.5099303 au, ω = meteor showers from the sporadic background, emphasizing that 290.7618◦, Ω = 269.9493◦, i = 171.9200◦, and T = a cutoff value chosen has to reflect the strength of the shower 2438608.7111 (1964 August 1.2111). We refer to this orbit compared to the local sporadic background, has recently been as the nominal orbit. The orbital period of the comet in the suggested by Moorhead(2016). nominal orbit is 390.993 yr. Since the meteoroids move in the orbits with a low absolute The uncertainity of the nominal orbit, determined in 1964, is inclination to the ecliptic, they hit Earth within a relatively long not known. Therefore, it is not possible to trace the uncertainity arc of its orbit, and the direction of the velocity vector of our of its past evolution. In our modeling of the theoretical stream, planet changes during the period of shower activity. The geo- we did not consider any set of cloned orbits, only the nominal centric radiant then changes correspondingly. To eliminate this orbit itself. We integrated this orbit backward in time, down to effect, we illustrate the radiant positions in the ecliptic coordinate 100 000 yr. The past evolution of the orbital elements is shown frame with the x-axis permanently directed to the Sun, that is, in Figs.1a f. − in the Sun-centered ecliptic coordinate frame. (If λ is the eclip- The minimum distance of the pre-perihelion and post- tic longitude of the radiant in the standard ecliptic coordinates perihelion arcs of the C/1964 N1 orbit from Earth’s orbit is and λ0 is the ecliptic longitude of the radiant in the Sun-centered shown in Fig.1g. In some time intervals, the orbital arcs ecliptic coordinates, then λ0 = λ λ , where λ is the solar approached the orbit of our planet relatively closely; the mutual longitude of the meteor.) − distance was shorter than 0.1 au or even shorter than 0.01 au. To integrate the orbits of the theoretical particles, par- Currently, the arcs are relatively far from Earth’s orbit; the ent comet, and perturbing planets, we used integrator RA15 pre-perihelion arc is at 0.19 au and the post-perihelion arc is at (Everhart 1985) within the software package MERCURY 0.41 au. (Chambers 1999). The gravitational perturbations of eight planets, Mercury to Neptune, were taken into account. 3. Modeling the stream In our simulations, the acceleration due to the Poynting–Robertson (P–R) effect was considered. The term The theoretical stream of the studied comet, C/1964 N1, was “P–R effect” is here used to refer to the action of radial electro- modeled in the way suggested by Neslušan(1999), which was magnetic radiation pressure as well as to the velocity-dependent later slightly modified (Tomko & Neslušan 2012). In the model- effects on the meteoroid particles. We used the improved ing, the orbit of the parent body is first integrated backward in formulas derived by Klackaˇ (2014). A more detailed description time to the moment of perihelion passage, which occurred clos- is given in our previous paper (Hajduková & Neslušan 2017), est to an arbitrarily chosen time t . In the perihelion, a cloud ev for example. Parameter β, being the ratio of the accelerations of 10 000 test particles around the parent body was modeled, due to both the P–R effect and the gravity of the Sun, was again and this entire assembly was integrated forward in time, up to regarded as a free parameter. the present. At the end of the integration, we selected the par- We created a series of models for various combinations of ticles moving in the orbits that approach Earth’s orbit within specific values of evolutionary time t and parameter β. In 0.05 au. They were used to predict the mean characteristics of ev reality, the stream consists of particles of various sizes and the expected shower. A brief summary of the method can also densities, and parameter β therefore ranges in a wider inter- be found in Neslušan et al.(2013b), Jakubík & Neslušan(2015), val of values. In addition, the particles are released at various and others. Since the method has been described several times, times, therefore their evolutionary time is different and can we do not repeat the description here. also acquire a value from a wider interval. Hence, the par- After selecting the particles that approach Earth’s orbit ticular model we created does not represent a whole stream. within 0.05 au, we searched for a corresponding shower in the The model of a whole stream is a composition of partial meteor databases, specifically in (1) the International Astro- models that give a good prediction of the corresponding real nomical Union (IAU) Meteor Data Center (MDC) photographic showers. database, version 2013 (Porubcanˇ et al. 2011; Neslušan et al. 2014), (2) the IAU MDC Cameras for Allsky Meteor Surveil- lance (CAMS) video database (Gural 2011; Jenniskens et al. 4. Predicted showers 2011, 2016a,c,b; Jenniskens & Nénon 2016), (3) the 2007 2015 Considering the evolutionary time, t , equal to 5, 10, 20, 40, SonotaCo video (SonotaCo 2009, 2016), and (4) the EDMOND− ev and 80 kyr and the P–R effect parameter β acquiring the val- video databases (Kornoš et al. 2014a,b). These databases contain ues 0.00001, 0.0001, 0.001, 0.003, 0.005, 0.007, and 0.009, we 4873, 110 521, 208 826, and 145 830 records on meteor orbits and constructed the theoretical streams of the studied comet for geophysical data, respectively. every possible combinations of tev and β values and followed 2 http://ssd.jpl.nasa.gov/sbdb.cgi the dynamical evolution of the created stream until the present.

A162, page 2 of8 L.L. Neslušan, Neslušan and M. Hajduková, Jr.:jr: Meteor Meteor showers of CC/1964/1964 N1

1 110 (a) (b) 0.95 100 0.9 90 0.85 80 0.8 70 0.75 0.7 60 semi-major axis [AU] perihelion distance [AU] 0.65 50 0.6 40 -100 -80 -60 -40 -20 0 -100 -80 -60 -40 -20 0 time [kyr] time [kyr]

0.994 300 (c) (d) 0.992 250 0.99 200 0.988 0.986 150 0.984 100 eccentricity [1] 0.982 50 0.98 argument of perihelion [deg] 0.978 0 -100 -80 -60 -40 -20 0 -100 -80 -60 -40 -20 0 time [kyr] time [kyr]

350 (e) 176 (f) 300 250 172

200 168 150 164

100 inclination [deg] 160 50

longitude of ascending node [deg] 0 156 -100 -80 -60 -40 -20 0 -100 -80 -60 -40 -20 0 time [kyr] time [kyr]

0.8 (g) 0.7 0.6 0.5 0.4 0.3 0.2 minimum distance [au] 0.1 0 -100 -80 -60 -40 -20 0 time [kyr]

Fig. 1. Behavior of perihelion distance (plot(panel a), a), semi-major semi-major axis axis (b), (panel eccentricity b), eccentricity (c), argument (panel of c), perihelion argument (d), of perihelion longitude of(panel ascending d), longitude node (e), of andascending inclination node to (panel the ecliptic e), and inclination(f) of the nominal to the ecliptic orbit of (panel comet f)C of/1964 the nominal N1. The orbit evolution of comet of C/1964 the minimum N1. The distance evolution between of the minimumthe orbital distance arcs of cometbetween C/ the1964 orbital N1 and arcs Earth of comet is shown C/1964 in plot N1 (g). and The Earth minimum is shown distance in plot of (panelthe post-perihelion g). The minimum (pre-perihelion) distance of the arc post-perihelion is shown by the (pre-perihelion) red solid (blue dashed)arc is shown curve. by All the plots red solid are constructed (blue dashed) for curve. the period All plots from aretime constructed 100 000 years for the before period the from present time to 100 the 000 present. yr before the present to the present. some values of evolutionary time, the P-R effect caused a deflec- also constructed some additional models when necessary (see For some values of evolutionary time, the P–R effect caused a We also constructed some additional models when necessary tion of the stream from the collisional course with Earth earlier their specification in Sect. 6.3). deflection of the stream from the collisional course with Earth (see their specification in Sect. 6.3). or later than for the initially last considered value of β = 0.009. earlier or later than for the initially last considered value of β = TheThe detailed detailed distribution distribution of ofthe thepositions positions of geocentric of geocentric radi- To determine when the effect is strong enough to cause the com- 0.009. To determine when the effect is strong enough to cause the antsradiants of the of particles the particles approaching approaching Earth’s orbit Earth’s within orbit 0.05au within at plete deflection, we also created a few models with other values complete deflection, we also created a few models with other val- the0.05 presentisau at the shown present in Fig.is shown 2 for fourin Fig. modelsin2 for four the models Sun-cente in thered of β than listed above (β = 0.006, 0.008, 0.010, and 0.011). We ues of β than listed above (β = 0.006, 0.008, 0.010, and 0.011). eclipticSun-centered coordinates. ecliptic The coordinates. radiants are The distributed radiants on are both distributedsides of the ecliptic. The northern and southern strands are further di-

Article number,A162, page page 3 3 of of8 A&A proofs:A&Amanuscript 616, A162 (2018) no. aa32829

15 15 (a) (b) 10 10

5 5

0 0

-5 -5 ecliptic latitude [deg] ecliptic latitude [deg]

-10 -10

-15 -15 250 255 260 265 270 275 280 285 290 295 250 255 260 265 270 275 280 285 290 295 sun-centered ecliptic longitude [deg] sun-centered ecliptic longitude [deg]

15 15 (c) (d) 10 10

5 5

0 0

-5 -5 ecliptic latitude [deg] ecliptic latitude [deg]

-10 -10

-15 -15 250 255 260 265 270 275 280 285 290 295 250 255 260 265 270 275 280 285 290 295 sun-centered ecliptic longitude [deg] sun-centered ecliptic longitude [deg]

Fig.Fig. 2. 2.PositionsPositions of of geocentric geocentric radiants radiants of of theoretical theoretical particles particlesgrouped grouped into into five five filaments filaments of of the the meteoroid meteoroid stream stream associate associatedd with with comet comet C C/1964/1964 N1.N1. The The radiants radiants of of particles particles in in the the F1 F1 (F2, (F2, F3, F3, F4, F4, and and F5) F5) fila filamentment are are plotted plotted with with red red pluses pluses (green (green crosses, crosses, blue blue asteri asterisks,sks, violet violet full full squares, squares, and cyan full circles). The positions are shown for four models of the C/1964 N1 stream characterized with (tev, β) equal to (20, 0.0001) (plot a), and cyan full circles). The positions are shown for four models of the C/1964 N1 stream characterized with (tev, β) equal to (20, 0.0001) (panel a), (40(40,, 00.003).003) (b),(panel (80, b0),.00001)(80, 0 (c),.00001) and (80(panel, 0.007) c), and (d).(80 To, show0.007) the( positionspanel d). of To the show radiants, the positions the Sun-cent of theered radiants, ecliptical the coordinate Sun-centered frame ecliptical is used. coordinate frame is used. vided into two separate concentrations of the orbits in space, We constructed plots like those in Figs. 3 and 4 for every whichon both is sidesalso seen of the in ecliptic. terms of The radiants northern that are and shown southern in the strands fig- filamentparticles in in each the core model, survive, where therefore the identification the extent of of a the predicte radiantd ure.are further divided into two separate concentrations of the orbits showerarea is toreduced. a real shower separated at least from a single database was successful. Together with tabular data, these figures served in space,Taking which into account is also seen this in structure, terms of we radiants divided that the are stream shown We constructed plots like those in Figs.3 and4 for every to remove some identifications, which seemed to be successful mostlyin the figure. into four filaments, two (F1 and F2) with the radiants filament in each model, where the identification of a pre- on the basis of the D-criterion, but the predicted and observed northwardTaking and into two account (F3 and this F4) structure, southward we of divided the ecliptic. the stream In a dicted shower to a real shower separated at least from a single radiant areas were unacceptably different (a more detailed de- fewmostly models into for fourt filaments,= 80kyr and two high (F1 values and F2) of β with(β = the0.005, radi- database was successful. Together with tabular data, these fig- ev scription of the identification is given in Sect. .5). 0.007,ants northward 0.009, and and 0.010), two (F3 only and a single F4) southward southern offilament the eclip- oc- ures served to remove some identifications, which seemed to According to Figs. 3, 4, and many similar others that we do curredtic. In (Fig. a few 2d). models In the for Sun-centeredtev = 80 kyr ecliptic and high coordinates values, of theβ be successful on the basis of the D-criterion, but the predicted not show, there is mostly no perfect match between a given pre- radiant(β = 0.005 area, 0.007, of this 0.009, filament and is 0.010), similar only to a that single of filament southern F4. fil- and observed radiant areas were unacceptably different (a more diction and a real shower. However, the P-R effect does not tend Aament more occurred detailed inspection (Fig.2d). In reveals the Sun-centered some systematic ecliptic differences coor- detailed description of the identification is given in Sect.5). to improve the match significantly. The meteoroid particles in indinates, the mean the parameters radiant area (a of higher this absolute filament orbital is similar inclinati to thaton or of According to Figs.3 and4, and many similar others that we the C/1964 N1 stream are quite large and the effect is not very lowerfilament solar F4. longitude), A more detailed however. inspection Hence, we reveals are not some sure system- if this do not show, there is mostly no perfect match between a given strong. In more detail, a good match can be found, typically, for filamentatic differences can be in identified the mean with parameters F4, and (a we higher rather absolute refer to orbital it as prediction and a real shower. However, the P–R effect does not β up to the value of about 0.001. F5.inclination Its occurrence or lower is solar discussed longitude), in Sect. however. 6.3. Hence, we are not tend to improve the match significantly. The meteoroid particles sure if this filament can be identified with F4, and we rather refer in theFurthermore, C/1964 N1 there stream is aare vague quite symmetry large and the of the effect filaments is not very F1 to itIn as Figs. F5. Its3 and occurrence 4, the positions is discussed of the in geocentric,Sun-center Sect. 6.3. ed andstrong. F4 and In more of F2 detail, and F3 a with good respect match tocan the be apex found, of typically,Earth’s mo- for radiantsIn Figs. of theoretical3 and4, theparticles positions and the of correspondingre the geocentric,al Sun- show- tion.β up The to the highest value number of about of 0.001. radiants of a given filament is found erscentered are shown radiants in some of theoretical models. In particles more detail, and the plotscorresponding of Fig. 3 in aFurthermore, single quadrant there (four isa filaments, vague symmetry F1 F4, inof fourthe filaments quadrants) F1 arereal related showers to filament are shown F3 in in the some models models. with In P-R-e moreffect detail, parame- the ofand the F4 apex-centered and of F2 and ecliptical F3 with coordinate respect− to system. the apex Howeve of Earth’sr, the terplotsβ = of0. Fig.000013 are and related a series to of filament evolutionary F3 in times, the modelstev. The with dis- distributionmotion. The into highest specific number quadrants of radiants is not exact. of a given Some filament radiant persionP–R effect of the parameter radiant areaβ = increases0.00001 withand aincreasing series oftev evolution-. Owing pointsis found are in beyond a single the quadrant pertaining (four filaments, to their F1–F4, filament in a fournd toary the times, largertev dispersion,. The dispersion some of particles the radiant are obviously area increases deflected with contaminatequadrants) ofother the filaments. apex-centered ecliptical coordinate system. fromincreasing the collisionaltev. Owing course to the with larger Earth, dispersion, therefore somethe numbe particlesr of However, the distribution into specific quadrants is not exact. particlesare obviously in the deflected filament decreases from the withcollisional the time. course with Earth, Some radiant points are beyond the quadrant pertaining to their 5. Identification of predicted with real showers thereforeThe heliocentric the number radiants of particles in Fig. in 4 the are filament related decreasesto filament with F2 filament and contaminate other filaments. the time. in the models for tev = 40kyr and a series of the values of β- The mean orbits of the predicted meteor showers were used as parameter.The heliocentric The P-R eff radiantsect on the in Fig.particle4 are dynamics related to in filament this fila- the5. Identification initial orbits in the of predicted iteration, made with within real showers the break-point mentF2 in is the evident. models The for efftevect= tends40 kyr to and move a theseries articles of the away values from of method, to separate possible real counterparts of the showers theβ-parameter. vicinity of The Earth’s P–R orbit effect with on theincreasing particleβ. dynamics Only the in parti- this fromThe meanthe meteor orbits catalogs. of the predicted Unfortunately, meteor the showers dependence were usedN = as filament is evident. The effect tends to move the articles away the initial orbits in the iteration, made within the break-point cles in the core survive, therefore the extent of the radiant area is N(Dlim) constructed within the method never exhibited a clear reduced.from the vicinity of Earth’s orbit with increasing β. Only the breakmethod, point; to separatetherefore, possible it was hard real to counterparts decide whether of the the showers sepa-

ArticleA162, page number, 4 of page8 4 of 8 L.L. Neslušan, Neslušan and and M. M. Hajduková, Hajduková, jr: Jr.: Meteor Meteor showers showers of of C C/1964/1964 N1 N1

0 0 (a) (b)

-2 -2

-4 -4

-6 -6

ecliptic latitude [deg] -8 ecliptic latitude [deg] -8

-10 -10

270 275 280 285 290 295 270 275 280 285 290 295 sun-centered ecliptic longitude [deg] sun-centered ecliptic longitude [deg]

0 0 (c) (d)

-2 -2

-4 -4

-6 -6

ecliptic latitude [deg] -8 ecliptic latitude [deg] -8

-10 -10

270 275 280 285 290 295 270 275 280 285 290 295 sun-centered ecliptic longitude [deg] sun-centered ecliptic longitude [deg]

0 (e)

-2

-4

-6

ecliptic latitude [deg] -8

-10

270 275 280 285 290 295 sun-centered ecliptic longitude [deg]

Fig.Fig. 3. 3.PositionsPositions of of geocentric geocentric radiants radiants of of theoretical theoretical particles particles(black (black dots) dots) in in the the predicted predicted filament filament F3 F3 and and corresponding corresponding real-shower real-shower meteors meteors of of thethe July Julyξξ-Arietids,shower-Arietids,shower 533, 533, separated separated from from the the CAMS-video CAMS-video (gree (greenn triangles) triangles) and and SonotaCo-video SonotaCo-video (red (red full full squares) squares) databas databases.es. The The positions positions are shown in the models for the P-R-effect parameter β = 0.00001 and a series of evolutionary times tev = 5 (plot a), 10 (b), 20 (c), 40 (d), and are shown in the models for the P–R effect parameter β = 0.00001 and a series of evolutionary times tev = 5 (panel a), 10 (panel b), 20 (panel c), 8040 kyr (panel (e). dTo), showand 80 thekyr radiants, (panel e the). To Sun-centered show the radiants, ecliptic the coordinate Sun-centered frame ecliptic is used. coordinate frame is used. ratedfrom set the of meteor meteors catalogs. truly was Unfortunately, a shower or onlythe dependence a random mod-N = ticlesWhen and a comparing high value the of β predictedimplies a and small real particle showers, size. we How- also erateN(Dlim accumulation) constructed of within meteors the in method the given never part exhibited of the orbita a clearl ever,considered the relation our models between with the size a relatively and parameter high valueβ is still of the largely P–R phasebreak space. point; Hence, therefore, the it reality was hard of the to mean decide orbits whether of the the sepa sep-- uncertainparameter forβ theand meteoroid the video-meteor material. Jakubík data. This & Neslušan may seem (2015) con- ratedarated showers set of is meteors rather uncertain. truly was a shower or only a random separatedtradictory the since real the Geminids, video techniques which have can an detect ecliptic relatively longitu largede o moderateThe relationship accumulation between of meteors the predicted in the and given separated part show-of the ofparticles the radiant and a down high value to 254 of.5β implies. The radiants a small particleof these size. particles How- ersorbital is also phase mostly space. uncertain. Hence, The the reality iteration of often the mean resulted orbits in aof real the canever, reach the relation this low between value onlythe size for and a β parameterparameterβ is approaching still largely meanseparated orbit showers that was is very rather diff uncertain.erent from the predicted mean orbit. 0.017.uncertain These for Geminids the meteoroid were material. separated Jakubík from the & IAU Neslušan MDC(2015 pho-) We calculatedThe relationship the Southworth-Hawkins between the predictedD-discriminant and separated between show- tographicseparated as the well real as Geminids, the video data, which however. have an Hence, ecliptic we longitude can ex- theers predicted is also mostly and corresponding uncertain. The real iteration mean orbits often and resulted exclud ined a pectof the that radiant some realdown particles to 254.5 with◦. The sizes radiants corresponding of these to particles up to allreal separated mean orbit mean that orbits was very with differentDSH > from0.2. Wethe predicted also discarded mean thecan highest reach consideredthis low valueβ-value only of for 0.010 a β areparameter present in approaching the video someorbit. separated We calculated real showers the Southworth–Hawkins if their geophysicalD data-discriminant were too data.0.017. These Geminids were separated from the IAU MDC pho- dibetweenfferent from the predicted the predicted and correspondingcounterpart. In real more mean detail, orbits the di andf- tographicWe also as calculated well as the the videoD-discriminant data, however. between Hence, every we pre- can ferenceexcluded in all mean separated solar longitude mean orbits should with notD exceed> 0.220.o We, or also the expect that some real particles with sizes corresponding to up to SH ∼ dicted and known orbit in the IAU MDC list of all showers and positiondiscarded of some the predicted separated mean real showers radiant if should their geophysical not be different data regardedthe highest as possibly considered relatedβ-value only of orbits 0.010 with are presentD in0 the.20. video The SH ≤ fromwere the too real different counterpart from by the more predicted than a dozen counterpart. degrees. In more criteriondata. DSH 0.20 is not very strict, therefore it is not sur- detail,When the comparing difference in the mean predicted solar longitude and real showers,should not we exceed also prisingWe that also a calculated single≤ real the shower,D-discriminant regardless between of whether every it w pre-as 20 , or the position of the predicted mean radiant should not dicted and known mean orbit in the IAU MDC list of all showers considered∼ ◦ our models with a relatively high value of the P-R separated from a considered database or found in the IAU MDC parameterbe differentβ and from the the video-meteor real counterpart data. This by more may thanseem a contra- dozen listand of regarded showers, as is possibly identified related with more only orbits than a with singleDSH predict0.ed20. degrees. The criterion D 0.20 is not very strict, therefore,≤ it is dictory since the video techniques can detect relatively large par- filament. Fortunately,SH ≤ the search for the minimum value of DSH Article number,A162, page page 5 5 of of 88 A&A proofs:A&Amanuscript 616, A162 (2018) no. aa32829

(a) (b) 10 10

8 8

6 6

4 4 ecliptic latitude [deg] ecliptic latitude [deg]

2 2

0 0 250 255 260 265 270 250 255 260 265 270 sun-centered ecliptic longitude [deg] sun-centered ecliptic longitude [deg]

8 8

6 6

4 4 ecliptic latitude [deg] ecliptic latitude [deg]

2 2

0 0 250 255 260 265 270 250 255 260 265 270 sun-centered ecliptic longitude [deg] sun-centered ecliptic longitude [deg]

Fig.Fig. 4. 4.PositionsPositions of of geocentric geocentric radiants radiants of of theoretical theoretical particles particles(black (black dots) dots) in in the the predicted predicted filament filament F2 F2 and and corresponding corresponding real-shower real-shower meteors meteors of of thetheǫ-Geminids,-Geminids, shower shower 23, 23, separated separated from from the the CAMS-video CAMS-video (green (greentriangles) triangles) and and SonotaCo-video SonotaCo-video (red (red full full squares) squares) database databases.s. The The positions positions are are shown in the models for the evolutionary time tev = 40 kyr and a series of the values of P-R-effect parameter β = 0.001 (plot a), 0.003 (b), 0.005 shown in the models for the evolutionary time tev = 40 kyr and a series of the values of P–R effect parameter β = 0.001 (panel a), 0.003 (panel b), (c),0.005 and (panel 0.007 c (d).), and To 0.007 show ( thepanel radiants, d). To the show Sun-centered the radiants, ec theliptic Sun-centered coordinate eclipticframe is coordinate used. frame is used.

6. Specific filaments betweennot surprising the given that real a single shower real and shower, a predicted regardless filament of leadswhether to 6. Specific filaments a unique association of shower and filament. it was separated from a considered database or found in the 6.1. Filaments F3 and F1, July ξ-Arietids IAU MDC list of showers, is identified with more than a 6.1. Filaments F3 and F1, July ξ-Arietids single predicted filament. Fortunately, the search for the min- We can clearly identify theoretical filament F3 with shower July D ξWe-Arietids, can clearly shower identify 533 in theoretical the IAU MDC filament list. F3 This with identificatio shower Julyn imumSince value a given of filamentSH between consists the of given meteors real on shower similar and or- a predicted filament leads to a unique association of shower and isξ-Arietids, consistent shower with the 533 result in the obtained IAU MDC by Šegon list. This et al. identification (2017). In bits, the orbital similarity and its evaluation with the help of is consistent with the result obtained by Šegon et al.(2017). In Dfilament.-discriminant is a reasonable way to identify the predicted fil- our current study, the similarity between the mean orbit of the Since a given filament consists of meteors on similar Julyour currentξ-Arietids study, and the the similarity predicted between mean orbit the mean of F3 orbit is charac- of the aments with the observed showers. In this context, we point out July ξ-Arietids and the predicted mean orbit of F3 is charac- theorbits, circumstance the orbital that similarity all predicted and its filaments evaluation of with the C the/1964 help N1 of terized by the very low D-discriminant DSH = 0.053 when we D terized by the very low D-discriminant DSH = 0.053 when we stream-discriminant have a low is absolutea reasonable inclination way toto identify the ecliptic the predicted ( i < 10 fil-o), consider the mean orbit determined by Šegon et al. (2014) and aments with the observed showers. In this context, we point out consider the mean orbit determined by Šegon et al.(2014) and and consequently, the long orbital arcs of stream meteoroid| | ≈ s are DSH = 0.070 for the mean orbit determined by Jenniskens et al. the circumstance that all predicted filaments of the C/1964 N1 DSH = 0.070 for the mean orbit determined by Jenniskens et al. situated in the vicinity of Earth’s orbit. Thus, the large difference (2016c). A slightly higher value, DSH = 0.078, characterizes the i < (2016c). A slightly higher value, D = 0.078, characterizes the instream mean have argumentof a low absolute perihelion inclination and mean to longitudeof the ecliptic (ascendi10ng◦), similarity when we compare our filamentSH F3 and the mean orbit | | ≈ similarity when we compare our filament F3 and the mean orbit nodeand consequently, can naturally the occur. long Moreover, orbital arcs the of meteoroids stream meteoroids of a give aren derived by Kornoš et al. (2014b). derived by Kornoš et al.(2014b). filamentsituated incan the collide vicinity with of Earth’sour planet orbit. during Thus, a the relatively large difference long pe- A real shower corresponding to filament F3, its models es- in mean argument of perihelion and mean longitude of ascending A real shower corresponding to filament F3, its models espe- riod. Our tolerance of 20o in solar longitude, mentioned above, pecially for tev = 20kyr, was also found in the SonotaCo video cially for t = 20 kyr, was also found in the SonotaCo video isnode therefore can naturally likely acceptable. occur.∼ Moreover, the meteoroids of a given fil- data and IAUev MDC CAMS data. No shower corresponding to ament can collide with our planet during a relatively long period. F3data was and found IAU MDC in the CAMS IAU MDC data. No photographic shower corresponding and EDMOND to F3 Our tolerance of 20◦ in solar longitude, mentioned above, is videowas found data sets. in the The IAU agreement MDC photographic between the and predicted EDMOND and video real ∼ data sets. The agreement between the predicted and real show- therefore likely acceptable. showers is better for tev 20kyr than for a shorter evolutionary TheThe di differencesfferences of of several several degrees degrees in in mean mean solar solar longitude, longitude, time.ers is Hence, better for wet canev conclude20≥kyr than that for the a ageshorter of the evolutionary July ξ-Arietids time. Hence, we can conclude≥ that the age of the July ξ-Arietids is at meanmean right right ascension, ascension, and and mean mean declination declination of of the the radiant radiant or or is at least 20,000 years. Inspection of models for tev = 80 kyr, thosethose of of several several tenths tenths of of an an astronomical astronomical unit unit in in perihelio perihelionn dis- dis- however,least 20 000 implies yr. Inspection that the age ofis models younger for thantev = this.80 kyr, Comparin however,g tancetance occur occur not not only only between between the the predicted predicted and and correspondin correspondingg theimplies predicted that the filament age is F3 younger to the real than showers this. Comparing also implies the tha pre-t realreal showers, showers, but but also also between between the the corresponding corresponding real real showe show-rs, thedicted real filament meteoroids F3 wereto the not real much showers influenced also implies by the that P-R the effect. real asers, separated as separated by us by in us this in work this work based based on various on various catalogs, catalogs, and Theirmeteoroids size corresponds were not much to β < influenced0.001. by the P–R effect. Their < betweenand between the real the showersreal showers as separated as separated from from a catalog a catalog and andthe sizeThe corresponds radiant area to β of filament0.001≈ . F3 is situated below the pro- correspondingthe corresponding showers showers in the in IAU the MDC IAU MDClist of showers,list of showers, which jectionThe of radiant the ecliptic area of≈ on filament the celestial F3 is sphere. situated Filament below the F1 pro-has arewhich also are mutually also mutually different different when determined when determined by various by authors. various ajection very similar of the meanecliptic orbit, on the but celestial its radiant sphere. area Filamentis situated F1 no hasrth- a Allauthors. these All diff theseerencesindicate differences that indicate no stricter that no criterion stricter of criterion a shower of wardvery similarof the ecliptic. mean orbit, Hence, but its F1 radiant can be area regarded is situated as a northward northern identitya shower than identity we considered than we considered can be used can for be the used showers for the origi showersnat- branchof the ecliptic. of the southern Hence, F1 F3. can Some be regarded showers as with a northern mean charac- branch ingoriginating in C/1964 in N1. C/1964 N1. teristicsof the southern resembling F3. those Some of showers F1 were with found mean in the characteristics IAU MDC

ArticleA162, page number, 6 of8 page 6 of 8 L. Neslušan and M. Hajduková, Jr.: Meteor showers of C/1964 N1 resembling those of F1 were found in the IAU MDC CAMS a filament that can be identified as F5 and is predicted to be video as well as in the SonotaCo video databases. However, these the dominant structure (except for F5, only a few meteors of real showers were predicted only with the help of models with F1 approached the orbit of our planet) at the present time. The tev = 80 and are very dispersed. They are also uncertain because stream that was later released from the parent, 75 kyr and 60 kyr the threshold used for their separation was found to be high, from ago, did not intersect Earth’s orbit. The model for tev = 60 kyr 0.32 to 0.40. Because of this uncertainty, we do not yet name predicts filament F1, but with only a few members. This absence these newly found showers. No shower in the IAU MDC list was of the stream at Earth’s orbit was interrupted for a period: fila- identified with F1. ments F1, F2, and F5 (and a weak F3) occur again in the model at tev = 70 kyr. 6.2. Filaments F2 and F4, -Geminids The filamentary structure becomes “normal”, consisting of the above described filaments F1 to F4, when the meteoroids Filaments F1 and F3 can be regarded as the northern and south- are released in time 50 kyr before the present and later. In the ∼ ern branches of the same stream. Similarly, filaments F2 and F4 model for tev = 50 kyr, the filamentary structure is similar to that are such branches, F2 is the northern and F4 the southern branch. for tev = 40 kyr (and β = 0.007), except for the circumstance that While filament F4 is not the most similar filament to any shower F1 is more abundant than F2 for tev = 50 kyr. in the IAU MDC list of all showers, filament F2 can probably be No real counterpart of F5 was separated in the considered identified with the -Geminids, shower 23, especially with the databases. We found only a vague similarity of its mean char- mean orbit of this shower as determined by Cook(1973). acteristics with the mean characteristics of ξ-Geminids, shower Filament F2 probably has its counterpart in the IAU MDC 718, which was found by Jenniskens et al.(2016a). The match is CAMS data. Furthermore, we found a certain similarity of the poor in mean solar longitude (difference between the predicted mean orbit of F2 and three modifications of a corresponding real and observed mean values 15 ), mean right ascension ( 10 ), ∼ ◦ ∼ ◦ shower in the SonotaCo data. We must be careful with this iden- mean declination ( 5◦), and mean inclination ( 10◦). Moreover, tification, however, since the predicted solar longitude is up to while Jenniskens et∼ al. gave the mean semi-major∼ axis as 5.8 au, 20◦ higher. The matching degree of the predicted and real helio- we predict 337.1 au. This quantity can differ widely even for a centric radiant positions in F2 is shown in Fig.4, where these well-established relationship, however. positions are plotted in the models for tev = 40 kyr and a series of the P–R effect parameter β. The predicted shower matches its real counterpart for a wide interval of β-values, from 0 to 7. Conclusions about 0.005. No real counterpart of filament F4 was found in the considered databases or in the IAU MDC list. We modeled a theoretical stream of comet C/1964 N1 (Ikeya). The models were characterized with a variety of free parameters, evolutionary time, and strength of the Poynting–Robertson drag 6.3. Filament F5 β to predict a part or parts of the stream that can collide with In the theoretical models for tev = 80 kyr and β 0.005, fila- Earth. This means that we aimed to predict a meteor shower (or ments F3 and F4, with radiant areas below the ecliptic,≥ disap- several of them) of the comet. peared. Instead of these filaments, a single filament, F5, appeared Our simulations imply the existence of four distinct filaments with an area of the standard geocentric radiant in the region near of the C/1964 N1 stream that might be observed in Earth’s atmo- the border of F3 and F4. If the radiants are plotted in the Sun- sphere as four individual showers. We labeled them F1 to F4. centered ecliptic coordinates, the radiant area is almost the same We found an indication that the orbit of the parent comet and its as the radiant area of F4 (see Fig.2d). Nevertheless, the differ- stream rapidly evolved in a period that ended about 50 kyr ago. ences in some other parameters do not disappear, therefore it is During this period, the orbital corridors of individual filaments reasonable to classify F5 as an extra filament. occupied a different space. The occurrence of this irregular filament is most likely a Since our modeling ended with a positive result (many parti- consequence of the considerable change in inclination of the cles occurred in the vicinity of Earth’s orbits at the present time), parent-comet orbit, which can be observed in Fig.1f. In the we then separated some corresponding showers from the consid- period from about 92 to 80 kyr, the inclination decreased from ered databases of real meteors and compared the prediction with 170 to 158 (i.e.,− the− absolute inclination increased from the observation. We also searched for the corresponding showers ∼ ◦ ∼ ◦ 10◦ to 22◦; the orbit was at a larger distance from the ecliptic). in the IAU MDC shower list. This∼ is the∼ effect of the temporary capture of C/1964 N1 into the We note, however, that the separation of real showers cor- Kozai resonance during that period. responding to the predicted ones was often not clear. When we The orbital evolution of stream meteoroids was likely simi- started the iteration procedure from different initial orbits, we lar and, hence, the dynamical behavior of the stream in a more obtained several modifications of, most probably, the same real distant past can be expected to be different from its behavior in a shower. The separated real showers contain few members, 28 at later period. To support this vague deduction based on the evolu- most, many of them consist of 10 or fewer members. tion of the parent-body orbit, we also created several additional The diffuse real counterpart of filament F3 was found in models. Since filament F5 in the models for tev = 80 kyr is most the video data, especially in the SonotaCo database. In the abundant in the model for β = 0.007, we constructed a set of IAU MDC list, this filament is clearly identified with the July models for β = 0.007 and a sequence of values of tev equal to 50, ξ-Arietids, shower 533. This identification has previously also 60, 70, 75, 78, 82, 85, and 90 kyr. been made by Šegon et al.(2014, 2017). The identification of No single meteor was predicted in any orbit within 0.05 au F2 with -Geminids, shower 23 that we made is less certain. of Earth’s orbit at the present time in the models for tev = 90, 85, Its real counterpart was identified mainly in the CAMS data. A or 82 kyr, but when we considered the particles released from real counterpart of filament F1 was also found in the CAMS and the parent 80 kyr ago, some of them dynamically evolved to the SonotaCo data. We suspect, moreover, that filament F5 might present-day filament F5. The particles released 78 kyr ago form be a prediction of the ξ-Geminids, shower 718. This shower

A162, page 7 of8 A&A 616, A162 (2018) also has meteoroids on retrograde orbits and a similar mean Babadzhanov, P. B., Kokhirova, G. I., Williams, I. P., & Obrubov, Y. V. 2017, argument of perihelion and mean longitude of the ascending A&A, 598, A94 node. The correspondence of some parameters is questionable, Beech, M. 2002, MNRAS, 336, 559 Chambers, J. E. 1999, MNRAS, 304, 793 however, although it is not clearly excluded. No real counterpart Cook, A. F. 1973, NASA Special Publication, 319, 183 of filament F4 was found in the databases or in the IAU MDC list. de León, J., Campins, H., Tsiganis, K., Morbidelli, A., & Licandro, J. 2010, No real shower corresponding to F4 was observed, probably A&A, 513, A26 because only relatively few particles are predicted to approach Everhart, E. 1985, in Dynamics of Comets: Their Origin and Evolution: Proceed- ings of IAU Colloq, 11 1984, eds. A. Carusi, & G. B. Valsecchi (Dordrecht: Earth’s orbit and thus collide with our planet. This number is an Reidel), Astrophysics and Space Science Library order of magnitude lower than the numbers in filaments F3 (in Giorgini, J. D., Yeomans, D. K., Chamberlin, A. B., et al. 1996, BASS, 28, 1158 the models for tev < 80 kyr), F2 (for tev > 5 kyr and a relatively Gural, P. S. 2011, in Proceedings of the 29th International Meteor Conference (Armagh, Northern Ireland), 2010, 28 low numbers are predicted for tev = 20 and 80 kyr), and F1 (for t > 20 kyr). We can expect that the abundance of a real shower Hajduková, M., & Neslušan L. 2017, A&A, 605, A36 ev Hajdukova, M., Rudawska, R., Kornos, L., & Toth, J. 2015, in Planetary and is proportional to the prediction. Consequently, if the databases Space Science, 118, 28 contain only a few tens of meteors of the real counterparts of F1 Hasegawa, I. 1999, in Meteroids 1998, eds. W. J. Baggaley & V. Porubcanˇ to F3, these data can be expected to contain only a few meteors of (Bratislava, Slovakia: Astronomical Institute of the Slovak Academy of F4 and F5 with the predicted number of the same magnitude as Sciences) 177 Jakubík, M., & Neslušan, L. 2015, MNRAS, 453, 1186 F4, and so showers with only a few particles cannot be separated Jenniskens, P. 2006, Meteor Showers and Their Parent Comets (Cambridge, UK: from the databases. Cambridge University Press) Analyzing the agreement between the predicted and real Jenniskens, P., & Nénon, Q. 2016, Icarus, 266, 371 showers, we can conclude that the meteoroids in the C/1964 N1 Jenniskens, P., & Vaubaillon, J. 2008, AJ, 136, 725 stream are older than about 20 000 yr. The particles in filaments Jenniskens, P., Gural, P. S., Dynneson, L., et al. 2011, Icarus, 216, 40 Jenniskens, P., Nénon, Q., Albers, J., et al. 2016a, Icarus, 266, 331 F1 to F4, which can collide with Earth at the present, could be Jenniskens, P., Nénon, Q., Gural, P. S., et al. 2016b, Icarus, 266, 355 released from the parent-body surface continuously in the period Jenniskens, P., Nénon, Q., Gural, P. S., et al. 2016c, Icarus, 266, 384 ranging from 50 000 to 20 000 yr in the past. Some older par- Jopek, T. J., & Kanuchová,ˇ Z. 2014, Meteoroids 2013, 353 ticles, with ages of up to 80 000 yr, might also survive in the Kanuchová,ˇ Z., & Neslušan, L. 2007, A&A, 470, 1123 Kasuga, T., & Jewitt, D. 2015, AJ, 150, 152 stream; they were ejected from the parent’s surface during some Klacka,ˇ J. 2014, MNRAS, 443, 213 specific short time intervals, however. The particles in filament Kornoš, L., Koukal, J., Piffl, R., & Tóth, J. 2014a, in Proceedings of the F5 could be released only during these intervals. International Meteor Conference, Poznan, Poland, 22-25 August 2013, eds. Filaments F1 to F4 should mostly contain relatively large M. Gyssens, P. Roggemans, & P. Zoladek, 23 particles corresponding to a P–R parameter β < 0.001. Only fil- Kornoš, L., Matlovic,ˇ P., Rudawska, R., et al. 2014b, Meteoroids 2013, 225 Kornoš, L., Tóth, J., Porubcan,ˇ V., et al. 2015, Planet. Space Sci., 118, 48 ament F5, if its real counterpart exists, contains≈ Earth-hitting Lindblad, B. A., & Olsson-Steel, D. 1990, Bull. Astr. Inst. Czechosl., 41, 193 particles that are small, corresponding to 0.005 < β < 0.010. McIntosh, B. A. 1990, Icarus, 86, 299 The radiant areas of four showers corresponding≈ ≈ to F1 F4 of Moorhead, A. V. 2016, MNRAS, 455, 4329 the stream of C/1964 N1 are close to the apex of the motion− of Neslušan, L. 1999, A&A, 351, 752 Neslušan, L., & Hajduková, M. 2014, A&A, 566, A33 Earth around the Sun. Among the showers studied by us or other Neslušan, L., Svoren,ˇ J., & Porubcan,ˇ V. 1995, Earth Moon Planets, 68, 427 authors, this property is exceptional. No other stream has been Neslušan, L., Hajduková, M., & Jakubík, M. 2013a, A&A, 560, A47 found with such a configuration of radiant areas of its showers. Neslušan, L., Kanuchová,ˇ Z., & Tomko, D. 2013b, A&A, 551, A87 In conclusion, comet C/1964 N1 is an active parent body of Neslušan, L., Svoren,ˇ J., & Porubcan,ˇ V. 2013c, Earth Moon Planets, 110, 41 at least one and possibly more real showers. The study of its Neslušan, L., Porubcan,ˇ V., & Svoren,ˇ J. 2014, Earth Moon Planets, 111, 105 Ohtsuka, K. 1989, WGN, J. Int. Meteor Organ., 17, 93 stream is worth to be repeated when more extensive meteor data Porubcan,ˇ V., & Kornoš, L. 2008, Earth Moon Planets, 102, 91 are collected. Porubcan,ˇ V., Štohl, J., & Svoren,ˇ J. 1992, Contrib. Astron. Obs. Skalnate Pleso, 22, 25 Acknowledgements. This article was supported by the realization of Project ITMS Porubcan,ˇ V., Svoren,ˇ J., Neslušan, L., & Schunová, E. 2011, in Meteoroids: The No. 26220120029, based on the supporting operational research and develop- Smallest Solar System Bodies, eds. W. J. Cooke, D. E. Moser, B. F. Hardin, ment program financed from the European Regional Development Fund. The & D. Janches (Washington D.C.: NASA) 338 work was also supported, in part, by the VEGA - the Slovak Grant Agency for Ryabova, G. O. 2007, MNRAS, 375, 1371 Science, grants No. 2/0037/18, and by the Slovak Research and Development Ryabova, G. O. 2008, in European Planetary Science Congress 2008, 226 Agency under the contract No. APVV-16-0148. Ryabova, G. O., & Rendtel, J. 2018, MNRAS, 475, L77 Šegon, D., Gural, P., Andreic,´ Ž., et al. 2014, WGN, J. Int. Meteor Organ., 42, 57 Šegon, D., Vaubaillon, J., Gural, P. S., et al. 2017, A&A, 598, A15 References SonotaCo. 2009, WGN, J. Int. Meteor Organ., 37, 55 SonotaCo. 2016, WGN, J. Int. Meteor Organ., 44, 42 Abedin, A., Spurný, P., Wiegert, P., et al. 2015, Icarus, 261, 100 Southworth, R. B., & Hawkins, G. S. 1963, Smithsonian Contributions to Abedin, A., Wiegert, P., Janches, D., et al. 2018, Icarus, 300, 360 Astrophysics (Washington D.C.: Smithsonian Institution), Vol. 7, 261 Arter, T. R., & Williams, I. P. 1997, MNRAS, 286, 163 Tomko, D. 2015, Planet. Space Sci., 118, 35 Babadzhanov, P. B. 1994, in 75 Years of Hirayama Asteroid Families: The Role Tomko, D., & Neslušan, L. 2012, Earth Moon Planets, 108, 123 of Collisions in the Solar System, eds. Y. Kozai, R. P. Binzel, & T. Hirayama, Tomko, D., & Neslušan, L. 2016, A&A, 592, A107 ASP Conf. Ser., 63, 168 Ueda, M. 2012, WGN, J. Int. Meteor Organ., 40, 59 Babadzhanov, P. B., Williams, I. P., & Kokhirova, G. I. 2008, MNRAS, 386, Vaubaillon, J., Colas, F., & Jorda, L. 2005, A&A, 439, 761 2271 Vereš, P., Kornoš, L., & Tóth, J. 2011, MNRAS, 412, 511

A162, page 8 of8