DOCSLIB.ORG

Turning Companions Into Planets - HST Astrometry of Exoplanet Candidates

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Turning Companions Into Planets - HST Astrometry of Exoplanet Candidates Turning Companions into Planets - HST Astrometry of Exoplanet Candidates G. F. Benedict & B. E. McArthur With help from G. Gatewood, A. Hatzes, W. Cochran, T. Forveille, G. Marcy, M. Endl P. Butler,Michelson 0M.507 2Mayor,9 G. Walker, T. Harrison, andC B.toP -Campbell 1 GFB HST/FGS Exoplanet Host Star Astrometry Outline • What astrometry brings to the party • Which targets to attack? • What we have done (exoplanet masses for – Gl 876b, c – 55 Cnc b, c, d, e – ε Eri b • Future work Michelson 050729 CtoP - 2 GFB Recommended Sozzetti, A. 2005. “Astrometric Methods and Instrumentation to Identify and Characterize Extrasolar Planets: A Review.” ArXiv Astrophysics e-prints arXiv:astro-ph/0507115. Michelson 050729 CtoP - 3 GFB Michelson 050729 CtoP - 4 GFB Michelson 050729 CtoP - 5 GFB Eclipsed light and HD 209458 - P = 3.52 DAYS - R = 1.27RJup Planet mass is unknown and depends on density (gas giant or rocky/metallic?) Michelson 050729 CtoP - 6 GFB Possible planets found by Radial Velocities By what? The Doppler Effect http://exoplanets.org/index.html Michelson 050729 CtoP - 7 GFB Michelson 050729 CtoP - 8 GFB Michelson 050729 CtoP - 9 GFB Eclipsed light and HD 209458 - P = 3.52 DAYS - R = 1.27RJup - M ~ 0.63MJup We know mass because we know the inclination (i ~90° from eclipse) Michelson 050729 CtoP - 10 GFB Other than multiple planet systems, these are not planets until either transits or astrometry provide orbit inclination http://exoplanets.org/index.html Michelson 050729 CtoP - 11 GFB The Questions 1. Do extrasolar planets exist? 2. How do we find them? 3. How far away from their parent stars are these planets? 4. Why was this a huge surprise? 5. How massive are these planets? 6. Do extrasolar planetary systems (analogous to our solar system) exist? Michelson 050729 CtoP - 12 GFB Gas giants close to their host stars should not have been a huge surprise. Goldreich and Tremaine (1980) predicted migration in the context of planetary rings. W. Ward (1986) predicted that most planetary migrations, in the presence of a nebular disk, would be inward. Michelson 050729 CtoP - 13 GFB Motivation Planet type depends upon mass. As for stars, mass critically determines most of the instantaneous characteristics and future evolution of a planet. Our present instruments and techniques can distinguish between brown dwarfs, gas giants, and rocky-cored Neptunes. Michelson 050729 CtoP - 14 GFB Michelson 050729 CtoP - 15 GFB The Goal of HST Astrometry - establish the semi-major axis size (thus, the inclination) of the perturbation to determine the mass of the perturbing object The Tools - small field relative astrometry using Fine Guidance Sensor 1r (FGS 1r) on Hubble Space Telescope - ground-based, high-precision radial velocities from multiple sources Our methodology is briefly outlined in Benedict et al. (2002, ApJL, 581, 115) where we estimated the mass of Gl 876b Michelson 050729 CtoP - 16 GFB Space Astrometry with an Interferometer on Hubble Space Telescope The Koester’s Prism - the Interferometric Heart of an FGS A B S = (A-B)/(A+B) Michelson 050729 CtoP - 17 GFB Astrometry, a simple example 5 "plates" different scales different orientations * * * * * * * * * * * * * * * * * * 1 2 3 * * * * 4 * * * * * * * * 5 Result of Overlap Solution to * * Plate #1 * * * Precision = standard deviation of the distribution of residuals ( ) from the * model-derived positions (*) Michelson 050729 I 0.002 arcsec CtoP - 18 GFB HST Astrometry Extrasolar Planetary Mass Targets Star d(pc) Sp. T. Status Proxima Cen 1.3 M5 Ve Upper Limits Barnard’s Star 1.8 M4 Ve Upper Limits Gl 876 4.7 M4V masses ρ1 = 55 Cnc 12.5 G8V masses ε Eri 3.2 K2V preliminary υ And 13.5 F8V in progress Michelson 050729 CtoP - 19 GFB Proxima Cen Periodogram 59 epochs Over 5.5y 30 m < Δt < 1 yr Benedict et al. 1999, AJ, 118, 1086 Michelson 050729 CtoP - 20 GFB Semi-major Axis of Circular Orbit (A.U.) 0.009 0.043 0.201 0.932 3 Astrometry limit Low-mass Companion from Monte-Carlo 2 Detection Limits Proxima Cen (M = 0.11 MO) analysis: 3-σ detection of 1 mas 1 RV Limit from Kurster perturbation 9 8 et al 1999 A&A, 344, 7 L5, 54 m s-1 precision 6 5 4 3 Mass of Saturn 2 Companion Detectable Mass (Jupiter = 1) 0.1 2 3 4 5 6 7 8 2 3 4 5 6 7 8 2 3 4 5 6 7 8 1 10 100 1000 Michelson 050729 Companion Period (days)CtoP - 21 GFB RV precision is now ~2.5 m s-1 (Kürster & Endl, 2004, ASP, 321, 84) Michelson 050729 CtoP - 22 GFB Lemons to Lemonade Rotation period of Proxima Cen from FGS millimag photometry Michelson 050729 CtoP - 23 GFB HST Astrometry Extrasolar Planetary Mass Targets Star d(pc) Sp. T. Status Proxima Cen 1.3 M5 Ve Upper Limits Barnard’s Star 1.8 M4 Ve Upper Limits Gl 876 4.7 M4V masses ρ1 = 55 Cnc 12.5 G8V masses ε Eri 3.2 K2V preliminary υ And 13.5 F8V in progress Michelson 050729 CtoP - 24 GFB Michelson 050729 CtoP - 25 GFB 24 data sets GJ 876 radial velocities Michelson 050729 CtoP - 26 GFB Michelson 050729 CtoP - 27 GFB Gl 876 and Gl 876b from a hypothetical moon orbiting Gl 876b Artist’s rendition courtesy of Lynette Cook Michelson 0507(http:29 //extrasolar.spaceart.org/) CtoP - 28 GFB Michelson 050729 CtoP - 29 GFB Michelson 050729 CtoP - 30 GFB GJ 876 We have determined relatively precise extrasolar planetary masses (not msini !!). We get the mass of component c by invoking coplanarity. Gl 876, M4V Mb = 1.89 ± 0.34MJup Mc = 0.56 ± 0.10MJup Michelson 050729 CtoP - 31 GFB HST Astrometry Extrasolar Planetary Mass Targets Star d(pc) Sp. T. Status Proxima Cen 1.3 M5 Ve Upper Limits Barnard’s Star 1.8 M4 Ve Upper Limits Gl 876 4.7 M4V masses ρ1 = 55 Cnc 12.5 G8V masses ε Eri 3.2 K2V preliminary υ And 13.5 F8V in progress Michelson 050729 CtoP - 32 GFB ρ1 Cnc (McArthur et al. 2004, ApJ, 614, L81) The Approach: use ground-based radial velocities to determine P, period; e, eccentricity; ω, longitude of periastron passage; T, time of periastron passage; K1, RV amplitude Michelson 050729 CtoP - 33 GFB ρ1 Cnc d = 55 Cnc d Perturbation due to component d, P = 4517 days α = 1.9 ± 0.4 mas i = 53° ± 7° Combining HST Mdsini = 3.9 ± 0.5MJ astrometry and ground- based RV Md = 4.9 ± 1.1MJ McArthur et al. 2004 ApJL, 614, L81 Michelson 050729 CtoP - 34 GFB The 55 Cnc (= ρ1 Cnc) planetary system, from outer- to inner-most ID r(AU) M (MJup) d 5.26 4.9 ± 1.1 c 0.24 0.27 ± 0.07 b 0.12 0.98 ±0.19 e 0.04 0.06 ± 0.02 = (17.8 ± 5.6M )o+ a Neptune!! Where we have invoked coplanarity for c, b, and e Michelson 050729 CtoP - 35 GFB To find planet e, HET access and cadence essential Michelson 050729 CtoP - 36 GFB HST Astrometry Extrasolar Planetary Mass Targets Star d(pc) Sp. T. Status Proxima Cen 1.3 M5 Ve Upper Limits Barnard’s Star 1.8 M4 Ve Upper Limits Gl 876 4.7 M4V masses ρ1 = 55 Cnc 12.5 G8V masses ε Eri 3.2 K2V preliminary υ And 13.5 F8V in progress Michelson 050729 CtoP - 37 GFB Our Approach Use FGS astrometry to determine α, semi-major axis of perturbation i, orbit inclination Ω, position angle of ascending node π, parallax of system µ, proper motion of system Use lower-precision ground-based astrometry to extend the time baseline to better define the proper motion and, eventually the perturbation ε ERI, 1989 - present Michelson 050729 CtoP - 38 GFB Our Approach, continued Simultaneous solution incorporating both astrometry and radial velocities • Constrain all plate constants to those determined from astrometry-only • Constrain K, e, P, ω to values determined only from radial velocities • Invoke (Pourbaix & Jorrisen 2000) constraint 2 " sin i PK1sqrt(1$ e ) A = # abs 2# % 4.705 •Solve for α, i, µ and π ! Michelson 050729 CtoP - 39 GFB • ε Eri age < 1 Byr (Di Folco et al. 2004, A&A 426, 601) • ε Eri has an associated dust disk (Greaves et al. 2005, ApJ 619, L187) • Dust disk inclination ~30° One might expect the planet orbital plane and the dust disk to be coplanar. Michelson 050729 CtoP - 40 GFB HST Astrometry of the extrasolar planet of ε Eridani 4 ! Eri " = 0.3107 arcsec (HIP) 3 M ~ 4.0 M , M ~ 0.45 M A O B O E M A ~ 0.8 M sun , M B ~ 0.0017 M sun ! = 1.9 mas, i = 133° -1 = 2.2 mas, i = 30° K1 = 2.8 km s # 2 2 N 1 2000.5 0 2001 mas 2001.5 0 mas -1 2002 -2 2002.5 HD 213307 2003 " = 3.63 mas -2 -3 2003.5 Possible orbit -3 -2 -1 0 1 2 3 2004 mas showing epochs of HST -4 observations Michelson 050729 -4 -2 0 C2toP - 41 GFB4 mas Hatzes et al. 2000, ApJL, 544, L148 California-Carnegie web site ε Eri is a chromospherically active star producing ΔV unrelated to companions Michelson 050729 CtoP - 42 GFB Also ε Eri FGS astrometry afflicted with poor distribution of, and very faint, reference stars The FGS has a dynamic range > 13 magnitudes. Michelson 050729 CtoP - 43 GFB ! Eri & MAP Reference Stars 1000 1 7 8 9 15 10 11 9 12 13 14 500 15 16 8 12 0 111 Y (arcsec) 10 7 -500 11 14 13 -1000 16 -1000 -500 0 500 1000 X (arcsec) Michelson 050729 CtoP - 44 GFB 2 " sin i PK1sqrt(1$ e ) A = # abs 2# % 4.705 ! The point cannot stray far from the curve because the errors on rhs are relatively small.
Load more

Recommended publications
  • Lurking in the Shadows: Wide-Separation Gas Giants As Tracers of Planet Formation
    Lurking in the Shadows: Wide-Separation Gas Giants as Tracers of Planet Formation Thesis by Marta Levesque Bryan In Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy CALIFORNIA INSTITUTE OF TECHNOLOGY Pasadena, California 2018 Defended May 1, 2018 ii © 2018 Marta Levesque Bryan ORCID: [0000-0002-6076-5967] All rights reserved iii ACKNOWLEDGEMENTS First and foremost I would like to thank Heather Knutson, who I had the great privilege of working with as my thesis advisor. Her encouragement, guidance, and perspective helped me navigate many a challenging problem, and my conversations with her were a consistent source of positivity and learning throughout my time at Caltech. I leave graduate school a better scientist and person for having her as a role model. Heather fostered a wonderfully positive and supportive environment for her students, giving us the space to explore and grow - I could not have asked for a better advisor or research experience. I would also like to thank Konstantin Batygin for enthusiastic and illuminating discussions that always left me more excited to explore the result at hand. Thank you as well to Dimitri Mawet for providing both expertise and contagious optimism for some of my latest direct imaging endeavors. Thank you to the rest of my thesis committee, namely Geoff Blake, Evan Kirby, and Chuck Steidel for their support, helpful conversations, and insightful questions. I am grateful to have had the opportunity to collaborate with Brendan Bowler. His talk at Caltech my second year of graduate school introduced me to an unexpected population of massive wide-separation planetary-mass companions, and lead to a long-running collaboration from which several of my thesis projects were born.
    [Show full text]
  • Naming the Extrasolar Planets
    Naming the extrasolar planets W. Lyra Max Planck Institute for Astronomy, K¨onigstuhl 17, 69177, Heidelberg, Germany [email protected] Abstract and OGLE-TR-182 b, which does not help educators convey the message that these planets are quite similar to Jupiter. Extrasolar planets are not named and are referred to only In stark contrast, the sentence“planet Apollo is a gas giant by their assigned scientific designation. The reason given like Jupiter” is heavily - yet invisibly - coated with Coper- by the IAU to not name the planets is that it is consid- nicanism. ered impractical as planets are expected to be common. I One reason given by the IAU for not considering naming advance some reasons as to why this logic is flawed, and sug- the extrasolar planets is that it is a task deemed impractical. gest names for the 403 extrasolar planet candidates known One source is quoted as having said “if planets are found to as of Oct 2009. The names follow a scheme of association occur very frequently in the Universe, a system of individual with the constellation that the host star pertains to, and names for planets might well rapidly be found equally im- therefore are mostly drawn from Roman-Greek mythology. practicable as it is for stars, as planet discoveries progress.” Other mythologies may also be used given that a suitable 1. This leads to a second argument. It is indeed impractical association is established. to name all stars. But some stars are named nonetheless. In fact, all other classes of astronomical bodies are named.
    [Show full text]
  • Fy10 Budget by Program
    AURA/NOAO FISCAL YEAR ANNUAL REPORT FY 2010 Revised Submitted to the National Science Foundation March 16, 2011 This image, aimed toward the southern celestial pole atop the CTIO Blanco 4-m telescope, shows the Large and Small Magellanic Clouds, the Milky Way (Carinae Region) and the Coal Sack (dark area, close to the Southern Crux). The 33 “written” on the Schmidt Telescope dome using a green laser pointer during the two-minute exposure commemorates the rescue effort of 33 miners trapped for 69 days almost 700 m underground in the San Jose mine in northern Chile. The image was taken while the rescue was in progress on 13 October 2010, at 3:30 am Chilean Daylight Saving time. Image Credit: Arturo Gomez/CTIO/NOAO/AURA/NSF National Optical Astronomy Observatory Fiscal Year Annual Report for FY 2010 Revised (October 1, 2009 – September 30, 2010) Submitted to the National Science Foundation Pursuant to Cooperative Support Agreement No. AST-0950945 March 16, 2011 Table of Contents MISSION SYNOPSIS ............................................................................................................ IV 1 EXECUTIVE SUMMARY ................................................................................................ 1 2 NOAO ACCOMPLISHMENTS ....................................................................................... 2 2.1 Achievements ..................................................................................................... 2 2.2 Status of Vision and Goals ................................................................................
    [Show full text]
  • 2001 Astronomy Magazine Index
    2001 Astronomy magazine index Subject index Chandra X-ray Observatory, telescope of, free-floating planets, 2:20, 22 12:76 A Christmas Star, 1:102 absolute visual magnitude, 1:86 cold dark matter, 3:24, 26 G active region 9393, 7:22 colors, of celestial objects, 9:82–83 Gagarin, Yuri, 4:36–41 Africa, observation from, 4:107–112, 10:48– Comet Borrelly, 9:33–37 galaxies 53 comets, 2:93 clusters of Andromeda Galaxy computers, accessing image archives with, in constellation Leo, 5:28 constellations of, 11:64–69 7:40–45 Massive Cluster Survey (MACS), consuming other galaxies, 12:25 corona of Sun, 1:24, 26 3:28 warp in disk of, 5:22 cosmic rays collisions of, 6:24 animal astronauts, 4:43–47 general information, 1:36–39 space between, 9:81 apparent visual magnitude, 1:86 origin of, 1:43–47 gamma ray bursts, 1:28, 30 Apus (constellation), 7:80–84 cosmology Ganymede (Jupiter's moon), 5:26 Aquila (constellation), 8:66–70 and particle physics, 6:39–43 Gemini Telescope, 2:26, 28 Ara (constellation), 7:80–84 unanswered questions, 6:46–52 Giodorno Bruno crater, 11:28, 30 Aries (constellation), 11:64–69 Gliese 876 (red dwarf star), 4:18 artwork, astronomical, 12:80–85 globular clusters, viewing, 8:72 asteroids D green stars, 3:82–85 around Zeta Leporis (star), 11:26 dark matter Groundhog Day, 2:96–97 cold, 3:24, 26 near Earth, 8:44–49 astronauts, animal as, 4:43–47 distribution of, 12:30, 32 astronomers, amateur, 10:88–89 whether exists, 8:26–31 H Hale Telescope, 9:46–53 astronomical models, 9:22, 24 deep sky objects, 7:87 HD 168443 (star), 4:18 Astronomy.com website, 1:78–84 Delphinus (constellation), 10:72–76 HD 82943 (star), 8:18 astrophotography DigitalSky Voice software, 8:65 HH 237 (meteor), 6:22 black holes, 1:26, 28 Dobson, John, 9:68–71 HR 1998 (star), 11:26 costs of basic equipment, 5:86 Dobsonian telescopes HST.
    [Show full text]
  • SILICON and OXYGEN ABUNDANCES in PLANET-HOST STARS Erik Brugamyer, Sarah E
    The Astrophysical Journal, 738:97 (11pp), 2011 September 1 doi:10.1088/0004-637X/738/1/97 C 2011. The American Astronomical Society. All rights reserved. Printed in the U.S.A. SILICON AND OXYGEN ABUNDANCES IN PLANET-HOST STARS Erik Brugamyer, Sarah E. Dodson-Robinson, William D. Cochran, and Christopher Sneden Department of Astronomy and McDonald Observatory, University of Texas at Austin, 1 University Station C1400, Austin, TX 78712, USA; [email protected] Received 2011 February 4; accepted 2011 June 22; published 2011 August 16 ABSTRACT The positive correlation between planet detection rate and host star iron abundance lends strong support to the core accretion theory of planet formation. However, iron is not the most significant mass contributor to the cores of giant planets. Since giant planet cores are thought to grow from silicate grains with icy mantles, the likelihood of gas giant formation should depend heavily on the oxygen and silicon abundance of the planet formation environment. Here we compare the silicon and oxygen abundances of a set of 76 planet hosts and a control sample of 80 metal-rich stars without any known giant planets. Our new, independent analysis was conducted using high resolution, high signal-to-noise data obtained at McDonald Observatory. Because we do not wish to simply reproduce the known planet–metallicity correlation, we have devised a statistical method for matching the underlying [Fe/H] distributions of our two sets of stars. We find a 99% probability that planet detection rate depends on the silicon abundance of the host star, over and above the observed planet–metallicity correlation.
    [Show full text]
  • Search for Brown-Dwarf Companions of Stars⋆⋆⋆
    A&A 525, A95 (2011) Astronomy DOI: 10.1051/0004-6361/201015427 & c ESO 2010 Astrophysics Search for brown-dwarf companions of stars, J. Sahlmann1,2, D. Ségransan1,D.Queloz1,S.Udry1,N.C.Santos3,4, M. Marmier1,M.Mayor1, D. Naef1,F.Pepe1, and S. Zucker5 1 Observatoire de Genève, Université de Genève, 51 Chemin des Maillettes, 1290 Sauverny, Switzerland e-mail: [email protected] 2 European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching bei München, Germany 3 Centro de Astrofísica, Universidade do Porto, Rua das Estrelas, 4150-762 Porto, Portugal 4 Departamento de Física e Astronomia, Faculdade de Ciências, Universidade do Porto, Portugal 5 Department of Geophysics and Planetary Sciences, Tel Aviv University, Tel Aviv 69978, Israel Received 19 July 2010 / Accepted 23 September 2010 ABSTRACT Context. The frequency of brown-dwarf companions in close orbit around Sun-like stars is low compared to the frequency of plane- tary and stellar companions. There is presently no comprehensive explanation of this lack of brown-dwarf companions. Aims. By combining the orbital solutions obtained from stellar radial-velocity curves and Hipparcos astrometric measurements, we attempt to determine the orbit inclinations and therefore the masses of the orbiting companions. By determining the masses of poten- tial brown-dwarf companions, we improve our knowledge of the companion mass-function. Methods. The radial-velocity solutions revealing potential brown-dwarf companions are obtained for stars from the CORALIE and HARPS planet-search surveys or from the literature. The best Keplerian fit to our radial-velocity measurements is found using the Levenberg-Marquardt method.
    [Show full text]
  • Astrometry with Hubble Space Telescope Fine Guidance Sensors a Review1
    Astrometry with Hubble Space Telescope Fine Guidance Sensors A Review1 G. Fritz Benedict2, Barbara E. McArthur2, Edmund P. Nelan3, and Thomas E. Harrison4 ABSTRACT Over the last 20 years Hubble Space Telescope Fine Guidance Sensor interfero- metric astrometry has produced precise and accurate parallaxes of astrophysical interesting stars and mass estimates for stellar companions. We review paral- lax results, and binary star and exoplanet mass determinations, and compare a subset of these parallaxes with preliminary Gaia results. The approach to single- field relative astrometry described herein may continue to have value for targets fainter than the Gaia limit in the coming era of 20-30m telescopes. Subject headings: astrometry | instrumentation: interferometers | techniques: interferometric | stars:distances | stars:low-mass | stars:planetary systems | exoplanets:mass 1. Introduction With Gaia poised to expand the astrometric reach of our species by many orders of magnitude (Cacciari et al. 2015), this article serves to highlight the far more modest, but nonetheless useful contributions made by Hubble Space Telescope (HST ) over the past 25 years. Several Fine Guidance Sensors (FGS) aboard HST have consistently delivered sci- entific results with sub-millisecond of arc precision in nearly every astronomical arena to which astrometry could contribute. These include parallaxes for astrophysically interesting arXiv:1610.05176v1 [astro-ph.SR] 17 Oct 2016 2McDonald Observatory, University of Texas, Austin, TX 78712 4Department of Astronomy, New Mexico State University, Box 30001, MSC 4500, Las Cruces, NM 88003- 8001 3Space Telescope Science Institute, 3700 San Martin Dr., Baltimore, MD 21218 1Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555.
    [Show full text]
  • Short-Term Dynamical Interactions Among Extrasolar Planets Gregory
    Short-Term Dynamical Interactions Among Extrasolar Planets Gregory Laughlin l, John E. Chambers 1 'NASA Ames Research Center, Moffett Field, CA 94035 Received .; accepted 2 ABSTRACT We show that short-term perturbations among massive planets in multiple planet systemscan result in radial velocity variations of the central star which differ substantially from velocity variations derivedassumingthe planets are exe- cuting independent Keplerian motions. We discusstwo alternate fitting methods which can lead to an improved dynamical description of multiple planet sys- tems. In the first method, the osculating orbital elementsare determined via a Levenberg-Marquardt minimization schemedriving an N-body integrator. The secondmethod is an improved analytic model in which orbital elements such as the periods and longitudes of periastron are allowed to vary according to a simple model for resonantinteractions betweenthe planets. Both of these meth- ods can potentially determine the true massesfor the planets by eliminating the sin i degeneracy inherent in fits that assume independent Keplerian motions. As more radial velocity data is accumulated from stars such as GJ 876, these meth- ods should allow for unambiguous determination of the planetary masses and relative inclinations. Subject headings: stars: planetary systems 1. Introduction Several thousand nearby stars are now being surveyed for periodic radial velocity variations which indicate the presence of extrasolar planets (Marcy, Cochran & Mayor 2000). In the past year, the pace of discovery has increased, and there are now nearly sixty extrasolar planets known. Recently, systems with more than one planet have been found, and four (v Andromedae, -3- GJ 876, HD 83443,and HD 168443)are now known.
    [Show full text]
  • The Role of Planet Accretion in Creating the Next Generation Of
    Draft version November 2, 2018 A Preprint typeset using LTEX style emulateapj v. 08/22/09 THE ROLE OF PLANET ACCRETION IN CREATING THE NEXT GENERATION OF RED GIANT RAPID ROTATORS Joleen K. Carlberg1, Steven R. Majewski1, and Phil Arras1 Draft version November 2, 2018 ABSTRACT Rapid rotation in field red giant stars is a relatively rare but well-studied phenomenon; here we investigate the potential role of planet accretion in spinning up these stars. Using Zahn’s theory of tidal friction and stellar evolution models, we compute the decay of a planet’s orbit into its evolving host star and the resulting transfer of angular momentum into the stellar convective envelope. This experiment assesses the frequency of planet ingestion and rapid rotation on the red giant branch (RGB) for a sample of 99 known exoplanet host stars. We find that the known exoplanets are indeed capable of creating rapid rotators; however, the expected fraction due to planet ingestion is only 10% of the total seen in surveys of present-day red giants. Of the planets ingested, we find that those∼ with smaller initial semimajor axes are more likely to create rapid rotators because these planets are accreted when the stellar moment of inertia is smallest. We also find that many planets may be ingested prior to the RGB phase, contrary to the expectation that accretion would generally occur when the stellar radii expand significantly as giants. Finally, our models suggest that the rapid rotation signal from ingested planets is most likely to be seen on the lower RGB, which is also where alternative mechanisms for spin-up, e.g., angular momentum dredged up from the stellar core, do not operate.
    [Show full text]
  • A Search for Multi-Planet Systems Using the Hobby-Eberly Telescope
    A Search for Multi-Planet Systems Using the Hobby-Eberly Telescope1 Robert A. Wittenmyer2,3, Michael Endl2, William D. Cochran2, Harold F. Levison4, Gregory W. Henry5 [email protected] ABSTRACT Extrasolar multiple-planet systems provide valuable opportunities for testing the- ories of planet formation and evolution. The architectures of the known multiple- planet systems demonstrate a fascinating level of diversity, which motivates the search for additional examples of such systems in order to better constrain their formation and dynamical histories. Here we describe a comprehensive investiga- tion of 22 planetary systems in an effort to answer three questions: 1) Are there additional planets? 2) Where could additional planets reside in stable orbits? and 3) What limits can these observations place on such objects? We find no evidence for additional bodies in any of these systems; indeed, these new data do not support three previously announced planets (HD 20367b: Udry et al. 2003, HD 74156d: Bean et al. 2008, and 47 UMa c: Fischer et al. 2002). The dynamical simulations show that nearly all of the 22 systems have large regions in which additional planets could exist in stable orbits. The detection-limit computations indicate that this study is sensitive to close-in Neptune-mass planets for most of the systems targeted. We conclude with a discussion on the implications of these non-detections. arXiv:0903.0652v1 [astro-ph.EP] 3 Mar 2009 Subject headings: stars: planetary systems – extrasolar planets 1Based on observations obtained with the Hobby-Eberly Telescope, which is a joint project of the Uni- versity of Texas at Austin, the Pennsylvania State University, Stanford University, Ludwig-Maximilians- Universit¨at M¨unchen, and Georg-August-Universit¨at G¨ottingen.
    [Show full text]
  • A Substellar Companion in a 1.3 Yr Nearly-Circular Orbit of HD 16760
    A Substellar Companion in a 1.3 yr Nearly-circular Orbit of HD 167601,2 Bun’ei Sato3, Debra A. Fischer4, Shigeru Ida5, Hiroki Harakawa5, Masashi Omiya6, John A. Johnson7, Geoffrey W. Marcy8, Eri Toyota9, Yasunori Hori5, Howard Isaacson4, Andrew W. Howard8, and Kathryn M.G. Peek8 [email protected] ABSTRACT We report the detection of a substellar companion orbiting the G5 dwarf HD 16760 from the N2K sample. Precise Doppler measurements of the star from Sub- aru and Keck revealed a Keplerian velocity variation with a period of 466.47±0.35 d, a semiamplitude of 407.71±0.84 m s−1, and an eccentricity of 0.084±0.003. Adopting a stellar mass of 0.78±0.05 M⊙, we obtain a minimum mass for the com- panion of 13.13±0.56 MJUP, which is close to the planet/brown-dwarf transition, and the semimajor axis of 1.084±0.023 AU. The nearly circular orbit despite the large mass and intermediate orbital period makes this companion unique among known substellar companions. Subject headings: planetary systems – stars: individual (HD 16760) 1Based on data collected at the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan. 2Based on observations obtained at the W. M. Keck Observatory, which is operated by the University of California and the California Institute of Technology. Keck time has been granted by NOAO and NASA. arXiv:0907.5080v1 [astro-ph.EP] 29 Jul 2009 3Global Edge Institute, Tokyo Institute of Technology, 2-12-1-S6-6 Ookayama, Meguro-ku, Tokyo 152- 8550 4Department of Physics & Astronomy, San Francisco State University, San Francisco, CA 94132 5Department of Earth and Planetary Sciences, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro- ku, Tokyo 152-8551 6Department of Physics, Tokai University, 1117 Kitakaname, Hiratsuka, Kanagawa 259-1292 7Institute for Astronomy, University of Hawaii, Honolulu, HI 96822 8Department of Astronomy, University of California, Berkeley, CA 9Kobe Science Museum, 7-7-6 Minatoshima-Nakamachi, Chuo-ku, Kobe, Hyogo 650-0046 –2– 1.
    [Show full text]
  • Origin of the Volatile Envelopes of Small-Radius Exoplanets
    Origin of the volatile envelopes of small-radius exoplanets. For submission to NASA Exoplanet Research Program 2015 (NNH15ZDA001N-XRP) 1. Table of contents. .......................................................................................................... 0 2. Scientific/Technical/Management. .............................................................................. 1 2.1 Summary. .................................................................................................................. 1 2.2 Goals of the Proposed Study. .................................................................................... 2 2.3 Scientific Background ............................................................................................... 2 2.3.1. Kepler planets 1.6 R⊕ < R ≲ 2.5 R⊕ typically have O(0.1–1 wt %) volatile envelopes whose source and timing is unknown. ................................................. 3 2.3.2. Outgassing has well-understood physical and chemical controls that have not previously been applied to exoplanets. ........................................................... 5 2.3.3. Combining outgassing with the modern understanding of dynamics can constrain the source of the volatile envelopes on Kepler’s small-radius planets. 6 2.4 Technical Approach and Methodology. .................................................................. 6 2.4.1. Description of geochemical model and dynamical model. ................................. 7 2.4.2. Simulation of outgassing during embryo growth. ..............................................
    [Show full text]