PoS(APCS2016)009 http://pos.sissa.it/ ∗ [email protected] Speaker. This article reviews historical developmenttoplatary of disks our have understanding been studied of by protoplanetaryinfrared various disks. to types radio of Pro- emissions. observations rangingvances from The in optical progress the through of observations. our Thisdisks. understanding They article deeply include reviews owes infrared various color technological (spectral methods ad- energyimaging, to distribution), and the identify Doppler indirect the shift evidences due protoplanetary such to as rotation, study of jets protoplanetary and disks. outflows. After It severalis also recent concluded lists topics with interesting up a the surveys short author useful summary. are for introduced, the it ∗ Copyright owned by the author(s) under the terms of the Creative Commons c ⃝ Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND 4.0). Accretion Processes in Cosmic Sources –5-10 APCS2016 September – 2016, Saint Petersburg, Russia Tomoyuki Hanawa Center for Frontier Science, Chiba University, 1-33E-mail: Yayoi-cho, Inage-ku, Chiba 263-8522, Japan Protoplanetary Disks – A Review PoS(APCS2016)009 (2.1) ], this 3 , denote ν and λ Tomoyuki Hanawa ]. He classified em- 1 , respectively. The SED slope is 3 2 − − do the flux per unit wavelength and = m. The roman numbers are assigned ≲ ν ) µ F ν α F ν ≲ ν ln ( and 3 d ln λ − d F − 1 , and = 0 ) λ ≲ F λ α λ ln ( ≲ d ln 2 d − , = 3 α + ≲ α < 0 ]. In his original classification scheme, class I, II, and III sources are defined as 2 The current classification of protoplanetary disks dates back to Lada [ SED is a good indicator for the radial extent of the protoplanetary disk. Each radial portion of The earliest evidence for a protoplanetary disk was brought from infrared observations of This section describes various methods of identifying protoplanetary disks. This article reviews historical development in our understanding of formation and structure of Protoplanetary disks have been interested by human beings for more than several centuries. the protoplanetary disk radiate in the wavelength corresponding the temperature thereof. An outer the wavelength and frequency, respectively, while classification was extended to an earlierinfrared counter object, part. class Thus 0 YSOs sources are which now have thought neither to optical evolve or from class near 0 to class III in general. those in the range of young stars. The spectral energy distributionbody (SED) having of the a naked stellar star radius. is Hence approximately the that SED of has a the black slope, in the infrared since the Rayleigh-Jeans approximation is valid. Here, the symbols, 2.1 Color Identification bedded young stellar objects (YSOs) intoLada & three Wilking classes [ according to the infrared SED obtained by often measured in the wavelengthaccording range to between the 2 and theoretical 25 expectationcess that decreases YSOs evolve with from time. classIII I sources Class to to III, II the i.e., sources weak the correspond lined infrared T to ex- Tauri the stars. classical Later T by Tauri André, stars Ward-Thompson & while Barsony class [ 2. Era of Identification the protoplanetary disks. We revieware the identified methods by of identifying the protoplanetaryemissions, spectral disks and energy in near distribution §2. infrared in They suggesting images the the showing presence infrared, of the Doppler a disk protoplanetary shiftedare disk. shape. molecular reviewed Surveys in providing line Also census §3. of listed Recent protoplanetarygiven observations are disks in and Indirect §5. some evidences topics are described in §4. A short summary is It is the 18-th centurycussed that the Emanuel nebular Swedenborg, hypothesis Immanuel on the Kant,had origin and of been Pierre-Simon the hypothetical Laplace Solar for dis- system. many However,progress the years in protoplanetary the and disks technology. the The progress observations includesresolution, of great and improvement them in sensitivity angular have in resolution, been all spectral the enabled wavelengths by ranging recent from X-ray to radio. Protoplanetary Disks 1. Introduction that per unit frequency, respectively. Protoplanetary disksis shine shallower in when the the infrared young and stars hence are the associated slope with them. PoS(APCS2016)009 0 au → (2.2) 1 300 = × J g. au CO emission. The 28 13 ] and references 2 360 10 Tomoyuki Hanawa 4 × → ] observed the disk 6 2 3 , 1 = − J km s CO 2 13 / 1 − ). ) au 2.2 r 100 ( 2 / 1 2 ) ] who observed M42 again with the HST after its ⊙ 8 M M ]). 1 4 ( 98 . ] resolved a rotating disk around GG Tau in the m in the SED. The dip is attributed to a wide gap in the disks 2 5 µ = 10 r ] discovered the silhouettes due to protoplanetary disks in the HST in their observation. This resolution corresponds to GM ≃ 7 0 λ √ ′′ . 2 = φ ] observed three class I sources and three low luminosity stars associated with × . denote the gravitational constant, the mass of the star, and the radial distance v 9 1 6 r ′′ ′′ ] evaluated the characteristic mass of ionized material to be . . 8 0 2 ∼ ] inferred to an embedded planet based on the distortion seen in the channel maps. , and 6 M , G The angular resolution has been progressively improved. Tang et al. [ O’Dell, Wen & Hu [ Padgett et al. [ The disk shape was elucidated by the Hubble Space Telescope (HST) thanks to its high angular Protoplanetary disks are supported by rotation against gravity. When the gravity is dominated Dutrey, Guilloteau & Simon [ SED depends on the viewing angle, i.e., the inclination of the disk to the line of sight. An edge- in the linear dimension fordependence the of assumed the distance rotation 140 velocity pc expressed and in was equation not ( enough to confirm the radial emission by using the IRAMthe interferometer. rotation although This some is earlierresolution recognized papers was as claimed the detection. earliest sure It detection should of be noted that the angular radial velocity increases from East toTang West et and al. some channel [ maps show typical “butterfly” shape. resolution of Herbig-Haro jets in the Taurusthese star sources forming were region found with to the have NICMOS circumstellar reflection camera nebulae on crossed board by HST. dark All lanes. The dark 2.3 Image Identification image of M42 (the Orionploplyds nebula) were and examined coined by the O’Dell term & “ploplyds” to Wen [ them. The properties of the therein for further details. postrefurbishment for the spherical aberation. Sinceback the ploplyds ground are emission, identified the by column absorption of massO’Dell the density & of Wen [ the disk can be derived with lower uncertainty. by the central star, the rotation velocity is evaluated to be where 2.2 Kinematical Identification from the star, respectively. An attempt to measure the rotation was initiated in 1980s. Protoplanetary Disks part of the disk is coolerthat and the the protoplanetary emission disks therefrom are is extendeddisks restricted in show class in a I a dip sources. longer wavelength. around A(see, class It e.g., of means a sources review named by transitional Williams & Cieza [ on disk may have anIt apparently is younger also SED since important the toamount inner and note part distribution that may of the be circumstellar SED hidden material. classification from See, our does e.g., view. not Williams give & Cieza a [ unique description of the around GG Tau with 50 au spatialobservation resolution by shows using the the 2D radio interferometer, distribution ALMA. of The the ALMA Doppler shift in the PoS(APCS2016)009 m) µ m), H (1.65 ]. They observed Tomoyuki Hanawa µ m. SST conducted 10 µ emission and variabil- α 2422. The names indicate that m to 160 m) images of the protoplanetary − µ µ point like sources including YSOs. 8 10 × 3 3 m) and K-band (2.0 µ m) bands. The survey cataloged µ emission and X-ray emission can be regarded as an evidence for accretion in some form (2.17 α Ophiuchi dark cloud region with the Einstein Observatry and detected many weak variable s Spitzer Space Telescope (SST) was launched with three instruments InfraRed Camera (IRAC), Several all sky surveys have been performedTwo successfully Micron in All-Sky these two Survey decades. (2MASS) observed the whole sky in the period 1997 to 2001 Many class 0 sources are designated by the name which are headed by IRAS and then fol- H As shown in the previous subsection, class I sources are often associated with jets and outflows. Currently high angular resolution is achieved by the large ground based telescope equipped ρ InfraRed Spectrograph (IRS), and Multiband2003. Imaging These Photometer instruments for cover Spitzer the (MIPS) wavelength in range August from 3.6 using the two telescopes, one in Arizona and the other in Chile, in the J (1.25 ities have served as indicatorsindicator for for the YSO YSO candidates. candidatethe since Also the X-ray seminal work emission by has Montmerle been et served al. as [ an these sources were discovered thoroughlite the (IRAS). all The sky IRAS survey satellite with wassources the launched during InfraRed in the Astronomical January 10 Satel- 1983 and monthsgalaxies. detected operation. a half The million infrared infrared sources include YSOs as well as external several surveys, the Gould Beltdinaire Survey, the (GLIMPSE), Galactic and Legacy Infrared “A Mid-Plane(MIPSGAL). 24 Survery and Extraor- 70 Micron Survey of the Inner Galactic Disk with MIPS" lowed by the right ascension and declination, such as IRAS 16293 3. Era of Survey sources, one half of which were already known to be YSOs at that time. and K Also class 0 sources are alsothat known jets to and be outflows can associated be withexpected regarded outflows. to as be The indirect oriented close evidence normal association for to implies the the protostellar jets disks. and outflows. The disks are and hence indirect evidence for the disks as reservoir for the accretion. H 2.4 Indirect Evidences with the adaptive optics. The H-band (1.6 Protoplanetary Disks lanes are the protoplanetary disks inupper the disk edge-on surfaces. view and the Thethe reflection reflection nebulae height nebulae correspond to indicate to the that the theperpendicular radius to disks increases the are with dark flared lane, the i.e., up, radius. the i.e., disk, the which The implies ratio Herbig-Haro that of jets the jets extend emerge in from the the disks. direction disks have been taken with suchby large a ground based corona telescopes. graph. OftenThe the origin The central of images stars the are often features masked remain showMayama unknown in spiral although this and several volume ideas for ring are some features proposed. examples. in See the the article protoplanetary by disks. PoS(APCS2016)009 ] pointed ]). When 14 15 ]) continuum. 12 Tomoyuki Hanawa mm) dust grains in 1 ∼ ]). Soon et al. [ 16 ] to all the azimuthal directions. 13 m to 3.16 mm by the dust having the µ 4 ]) and 0.89 mm (Fukagawa et al. [ 11 mm emission is ascribed to relatively large ( 1 ∼ O (3-2) emission is consistent with the Keplerian rotation. ] have extended the analysis by Muto et al. [ 18 14 ] have evaluated the dust and gas distribution in the northern and southern parts of 13 Soon et al. [ HD142527 is a Herbig Fe star star surrounded by a transitional disk exhibiting a wide gap with Gas and perhaps small dust grains are distributed less asymmetrically in the transitional disk. As shown in the previous sections, the technological advances in observations have broadened Catalogues made by the surveys serve for selection of sources for targeted observations. At These surveys are useful for constructing the SED of YSOs. The far infrared emission was power law size distribution with the maximumthe radius northern of disk 1 than mm. the The gas.emission dusts The are has more gas sharp concentrated is in inner spreadderived also and from in outer the the C edges, radial direction. the While gas the is continuum distributed more broadly. The gas motion the disk based on the radiative equilibriumand model which emission takes of account of radiation the in absorption, the scattering, wavelength range of 0.1 a radial width of approximatelyan 100 arc au. when The seen transitional in 1.3 disk mm is (Casassus highly et asymmetric al. and [ looks like Muto et al. [ 4.1 HD142527 The northern part of the diskamounts is to very 60. bright while Since the the southernthe part protoplanetary is disk, dark. the The observations brightnessradial indicate contrast and that azimuthal the directions. dust grains are concentrated in both the They find that the emission fromtional the opacity north model western is disk applied. cannot be Theassumption reproduced conventional a opacity as dust model far grain (i.e., as is the the Mie a conven- the theory) sphere dust employs of radius the a is uniform comparable dielectricby to constant a the (see, factor photon e.g., of wavelength, Draine 10. scattering [ optical dominates The depth over scattering is the reduces larger absorption emergent thanout radiative unity a flux (see, possibility substantially e.g, that when the Rybicki the real and scattering effective Lightman opacity [ can be much smaller than the conventional value. our knowledge on the protoplanetarybrought disks from in the these radio interferometer, three ALMA. decades. ALMAsecond has in Very improved the recent angular millimeter progress resolution and to has sub-millimeter subbeen been observations. arc- very At much the improved thanks same to time,ones. many the ALMA antennas, image has currently quality been fifty has providing interesting four topicsdisks. 12 in m This the study ones section of and shows star several twelve formation topic 7 and interesting protoplanetary m the author. the same time, the catalogues areof used each to class census is the often population derivedsomehow of from constant each and the subcategory. that population The all under life the the time YSOs tacit follow assumptions more that or the less birth similar rate evolutionary paths. is 4. Era of Imaging measured by the Herschel Spacewas Observatory not in conducted. the years from 2009 to 2913 although the survey Protoplanetary Disks PoS(APCS2016)009 ] for the 18

150 ) -2

100 Tomoyuki Hanawa 0.5 50 (Jy arcsec . ν 05 0 ◦ (AU) . log I x 0.0 0  -50 shows our model intensity maps. band 7 (0.871mm) 72 ◦ 1 . -0.5 -100 46

0 -150 50

-50

100

-100

y (AU)

0.0 150 ) 5 -2

100 -0.5 (Jy arcsec 50 ν ]. The radio observation revealed that the protoplanetary 0 (AU) 17 log I x -1.0 -50 band 3 (2.88mm) mm in the conventional opacity model. 87 -100 -1.5 . 0

0 = -150 50

-50 100

-100 λ

y (AU) = 2.9, 1.3 and 0.87 mm [ Model intensity maps for HL Tau. The left and right panels denote the intensity distributions at λ The large scattering opacity affects the model image seriously. First the dark rings are ob- K. Mochida and I have constructed a multi-color model for the HL Tau disk with the above HL Tau is an ideal target for modeling the protoplanetary disk since the disk is highly symmet- HL Tau was observed during the 2014 ALMA long baseline campaign in the wavelength scured. Second the peak brightness isone reduced, although i.e., the the disk intensity is is opticallyThe much thick. dark lower Both than rings of the are them blackbody clear contradict and with the the observed SED intensity is maps. close to the blackbody one in the region of a few tens au Figure 1: 2.88 and 0.87 mm, respectively.conventional The model left opacity half is of employed. eachscattering panel opacity The is shows artificially right the reduced intensity half by for of a the each factor model of panel in 10. shows which that the for model in which the mentioned constraints in mind. Theopacity model model may image overestimate also the scattering suggests efficiency. a Figure possibility that the conventional ric around the rotation axis.from This the means disk that and we we can canometrically derive argue thin many and the constraints flat viewing from otherwise angle the the dependentThis data. near means radiation First side that the the should radio protoplanetary be disk disk significantlyradio should consists different disk of be from and at ge- the least the far two flared side. components, disknear the irradiating infrared geometrically the images thin of near HL infrared. Tau.) (See, e.g., Murakawa et al. [ The left half of each panelwhile denotes the the model right image half obtained with doesreduced the that artificially conventional opacity obtained by model, with a the factorabsorption model opacity of at opacity 10. in which The the scattering scattering opacity opacity is is by a factor of 10 larger than the bands, Protoplanetary Disks 4.2 HL Tau disk consists of thin concentrichave multiple many rings. gaps of In which otherdirection origin words, so is the that still disk the inclination unknown. is was geometrically The precisely thin evaluated disk to and is be highly symmetric in the azimuthal PoS(APCS2016)009 2 H 3 (4.1) (4.2) ]). 20 ] observed the 19 Tomoyuki Hanawa CO (3-2) lines. The , 2 13 / 1 1 ] 2 ) c r r ( − c O (3-2), and r r 2 18 [ c r GM √  6 = 2 ) r ℓ ] observed infalling envelope and rotating disk around the ( 21 − r GM 2 , 2 √ ℓ GM  = = r c r ] argue that the transition takes place not at the centrifugal radius but at the v 21 A follow-up observation by Takakuwa et al. arXiv1702.05562 will appear in ApJ. A clue for the question may come from observations of a low mass protostar embedded in a An important question, in which phase a newly born star has its protoplanetary disk, may be Sakai et al. [ L1551 NE is binary of which components are protostars. Takakuwa et al. [ The good agreement between the observation and simulation indicates that gravitational torques 1 protostellar core, L1527. Sakai et al. [ still controversial. It is partlycient because resolution still and/or some lack recent of important numerical physical simulations processes suffer (see, from e.g., insuffi- Machida et al. [ centrifugal barrier. Here the centrifugalbalanced radius with the means gravity. the radius TheThey at radius argue that which of a the the gas centrifugal centrifugal element reacheswithout barrier force once loosing is is the its a centrifugal energy barrier half and if of angularthat it momentum. the accretes of centrifugal The from a a gravitational point radius. distant potential mass place is in approximated their by argument. Then the radial velocity is evaluated to be 4.4 L1527 protostar with ALMA. They foundfrom a the sharp protostar. A transition rotating-infalling in rotatingin chemistry envelope is and the traced kinematics with region emission around beyond from 100 100peaked cyclic-C au emission au. centered at On the the protostar.100 This other au indicates in hand that this the object. the disk SO outer line boundary emission is shows located at a compact single- 4.3 L1551 NE of the binary constitute the primarythrough driver for the exchanging circimbinray angular momentum disk so oftial as L1551 resolution to since permit NE. infall the It observation is waslower. interesting performed Higher in to spatial November observe resolution 2012 will the and show the binary the resolution in circumstellar then higher disks was clearly. spa- Protoplanetary Disks from the central star in themodel observation. opacity. We need to reconsider the validity of the conventional dust circumbinary disk with ALMAcircumbinary in disk 0.9 shows mm two opposing continuum,circumbinary bright disk. C U-shaped The features molecular in linestation the trace there. 0.9 non-axisymmetric mm deviation These continuum from observedtorques the map. of features Keplerian the ro- are binary. explained Bytorque by using produces a spiral surface numerical arms density simulation, enhancement induced they throughshaped have by spiral confirmed features. shock the that waves The gravitational the in deviation gravitational the fromto location the the of Keplerian angular the rotation momentum U- loss coincides by withcoincide the the with shock inward the waves simulation. motion in the due simulation. Both the continuum and lines PoS(APCS2016)009 49 Tomoyuki Hanawa the IAU Symposium 286 (1994) 149 once and then flows 2 / c r A&Ap. , = ]. Ann. Rev. Astron. Astrophys. r , 23 406 (1993) 122 in proceedings of ApJ , 7 Submillimeter continuum observations of Rho Ophiuchi A ], although the former shows a different interpretation. ) fits with their data. Similar kinematics are observed 24 4.1 Images of the GG Tau rotating ring ] do not take account of fluid effects. However, a gas element 287 (1984) 610 , D. Reidel (1987) 1 21 ApJ Protoplanetary Disks and Their Evolution , ) indicates that the gas element reaches The nature of the embedded population in the Rho Ophiuchi dark cloud - 4.1 ] and Sakai et al. [ 22 Star formation - From OB associations to protostars denote the specific angular momentum of the gas element and the centrifugal radius, c r . The panels show the 2D simulation of an accreting young star. The protoplanetary disk 2 and ℓ (2011) 67 A. Dutrey, S. Guilloteau, M. Simon, J.P. Williams, L.A. Cieza, C.J. Lada, No. 115, Star Forming Regions C.J. Lada, B. Wilking, Mid-infrared observations P. André, D. Ward-Thompson, Barsony, M. - The candidate protostar VLA 1623 and prestellar clumps The author thanks K. Mochida for his contribution to the numerical modeling of HL Tau. Thanks to the great advances in the observations our knowledge on the protoplanetary disks The model of Sakai et al. [ [5] [2] [3] [4] [1] This manuscript owes to discussionsin with the §4. collaborators of He the alsoPetersburg. author thanks This on work the the was objects LOC supported discussed JSPS of in KAKENHI ACPS part Grant by 2016 Number MEXT JP15K05017. for KAKENHI their Grant warm Number 26103702 hospitality and during hisReferences stay in St. have been very much broadened.jects. We They have are much useful observationalall for data the constructing and basic models questions constraint have for for been eachrently resolved. many object. discussed Even ob- (see the However §4). earliest this stage Also of does thefeatures the evolutionary not are protoplanetary path mean disk has still that is not mysterious cur- been and fixed.that the Highly only non-axisymmetric formation outer mechanism part is ofresolution the not is protoplanetary settled. of disks It the are should order spatiallymodeling for be resolved. of structure also 10 The of noted au current the inner for highest disk. spatial the nearby star forming regions. We still need theoretical 5. Short Summary will be decelerated by pre-existingoutwards. disk Do or the another gas elements gas reach element thein accreting centrifugal Figure barrier earlier continuously? and One now possibility flowing is is shown assumed to be geometricallyshot thin at and the time the indicated infalling on envelopesimulation the is suggests top thick. of heating the by Each diagram. shock, panelbarrier. The which shows inflow may and a induce outflow snap coexist chemical vertically. change The around the centrifugal Protoplanetary Disks where respectively. Equation ( Another object showing similar kinematics is found by Oya et al. [ back to the centrifugalby radius. Ohashi et Eq. al. [ ( PoS(APCS2016)009 436 ApJ , 117 (1999) Tomoyuki Hanawa ApJ , HUBBLE SPACE ) by arrows. The top left z v , r v 410 (1993) 696 8 ApJ Mapping CO Gas in the GG Tauri A Triple System with 50 , Discovery of new objects in the Orion nebula on HST images - Shocks, 820 (2016) 19 ApJ Postrefurbishment mission Hubble Space Telescope images of the core of the , 2D axisymmetric simulation for dynamical accretion onto protostar with a disk. Each panel 1490 compact sources, and protoplanetary disks D.L. Padgett, W. Brandner, K.R. Stapelfeldt, S.E. Strom, S. Tereby, D. Koerner, Y.-W. Tang, A. Dutrey, S. Guilloteau etau al. Spatial Resolution C. R. O’Dell, Z. Wen, X. Hu C. R. O’Dell, Z. Wen, (1994) 194 TELESCOPE/NICMOS Imaging of Disks and Envelopes around Very Young Stars Orion Nebula: Proplyds, Herbig-Haro objects, and measurements of a circumstellar disk [9] [7] [8] [6] Figure 2: denotes the density distribution by color, the rotation velocity by contour, and ( denotes the initial condition. This simulation is performed in a non-dimensional unit. 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López-Sepulcre et al., M. Machida, S. Inutsuka, T. Matsumoto, N. Sakai, T. Sakai, T. Hirota, N. Ohashi, K. Saigo, Y. AsoL1527 et IRS: al., Transformation from Infalling Motions to Kepler Motions Y. Oya, N. Sakai, A, López-SepulcreChange et in al., the Envelope of IRAS 16293-2422 Source A Studied with ALMA around the Class I Protostar IRAS 04365+2535 S. Takakuwa, M. Saito, K. Saigo, T. Matsumoto, J. Lim, T. Hanawa, Ho, P.T.P. Ophiuchi Dark Cloud: an X-ray Christmas Tree ApJ 493 (2013) 191 Protoplanetary Ring Surrounding HD 142527 in the disk of HD 142527 B.T. Draine, G.B. Rybicki, A.P. Lightman, A. Partnership, C.L. Brogan, L.M. PérezResults et from al. High Angular Resolution Observations toward the HLK. Tau Murakawa, Region S. Oya, T.-S. Pyo,low-mass M. proto-stellar Ishii, object HL Tauri Exchange by Gravitational Torques and InfallL1551 in NE the Circumbinary Disk of the Protostellar System K.-L. Soon, T. Hanawa, T. Muto, T. Tsukagoshi, M. Momose, T. Montmerle, L. Koch-Miramond, E. Falgarone, J.E. Grindlay, S. Casassus, G. van der Plas, S. Perez M, et al., M. Fukagawa, T. Tsukagoshi, M. Momose et al., T. Muto, T. Tsukagoshi, M. Momosethe et disk al. of HD 142527 and the indication of gas depletion [24] [21] [22] [23] [19] [20] [17] [18] [14] [15] [16] [11] [12] [13] Protoplanetary Disks [10]