DOCSLIB.ORG

Debris Dust Around Main Sequence Stars

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Debris Dust Around Main Sequence Stars Debris Dust Around Main Sequence Stars et al. (2013) Kalas Chris5ne H. Chen STScI, September 2016 1 Exoplanetary Systems Exoplanet Observaons Debris Disk Observaons 2 Outline • The HR 4796 System • Training Students Using the KecK LWS • Spitzer GTO Programs – A Search for Terrestrial Planetary Debris Systems and Other Planetary Debris DisKs – Spectroscopy of Protostellar, Protoplanetary and Debris DisKs – Dust Around Main Sequence A-type Stars – The Fabulous Four Debris DisKs 3 Early Debris DisK WorK Timeline • 1983 IRAS launches • 1984 Smith & Terrile spaally resolve the β Pic disK in scaered light using a coronagraph • 1986 Gille] accurately measures “infrared excess” toward Vega, Fomalhaut and β Pic from pointed IRAS observaons • 1991 Jura discovers HR 4796 IRAS infrared excess • 1991 Telesco and KnacKe discover spectroscopic evidence for silicates around β Pic • 1993 BacKman review ar5cle “Main Sequence Stars with Circumstellar Solid Material: The Vega Phenomenon” is published in Protostars and Planets III • 1998 Koerner and Jayawardhana resolve the HR 4796A disK in thermal emission using KecK/MIRLIN and Blanco/OSCIR • 2003 Spitzer launches • 2014 Gemini Planet Imager commissioning HR 4796A Infrared Excess Discovery HR 4796B Secondary Star Discovery • First es5mate for the grain temperature based on simple blacK body modeling, Tgr = 110 K with a predic5on for the distance of the grains from the star, ~40 AU • First grain size constrain (> 10 μm) based on the upper limit for the size of the system (<5” at 20 μm) • First calculaon of the Poyn5ng-Robertson drag life5me for this disK demonstrang that it must be a debris disK HR 4796A Planetary Companion Constraints • Central clearing may be created by a planetary mass object • SpecKle observaons constrain the mass to be < 0.125 M¤ The HR 4796A DisK Resolved! (Leo) HST NICMOS F1600W and F1100W coronagraphic images showing discovery of the light scaered from the dust (Schneider et al. 1999) (Right) KecK MIRLIN and 12.5 and 20.8 μm composite image from Koerner et al. (1998); (Far Right) CTIO Blanco 4-m OSCIR IHW18 from Jayawardhana et al. (1998) of the resolved dust thermal emission. GPI K1-Pol Commissioning Observaons of HR 4796 Perrin et al. 2015 • Total intensity phase func5on appears isotropic (consistent with small par5cles) • The North side of the disK is brighter in polarized light (rather than the ansa) • Suggests that the disK is marginally op5cally thicK Young Stars Possess Dusty Debris Young Stars Possess Dusty Debris Training Students using the KecK LWS Lipscy & Plavchan (2004) Stellar Wind Drag • Ac5ve stars have high mass loss rates that can impact the dust dynamics ! $! ! 2 $ ! C0LIR M SW c M d = # 2 &#1+ & " c %" L* % 4πaρ D2 t gr sw = ˙ 3Qsw M sw € (1) A Search for Terrestrial Planetary Debris Systems and Other Planetary Debris DisKs • Collaborave GTO project (Low, Werner, Jura, and Gehrz) with each GTO contribu5ng their own program • MIPS 24 and 70 μm observaons of 150 nearby (<150 pc), solar-liKe members of Upper Centaurus Lupus (UCL) and Lower Centaurus Crux (LCC) as determined from Chen, Jura et al. (2005) Hipparcos observaons (de Led to the discovery of a dozen disks as dusty as β Pic Zeeuw et al 1998.) ScoCen DisKs Resolved in Scaered Light Kalas et al. (2015) Currie et al. (2015) HD 106906 Draper et al. (2015) ScoCen Companions Detected in Debris DisKs Kalas et al. (2015) HD 95086 Rameau et al. (2015) (2) Spectroscopy of Protostellar, Protoplanetary, and Debris DisKs • Collaborave GTO project to obtain IRS observaons of 650 young objects in nearby star forming regions • Contributed 5me to study ~100 IRAS-discovered infrared excess sources (both protoplanetary and debris disKs) • IRS DisKs program led by Dan Watson (University of Rochester) Sloan et al. (2007) Hypothesized that class C PAH sources contain fragile aliphac materials that have not been subjected to strong UV fields Spectroscopic Constraints on Debris DisKs Dust Spaal Distribuon Dust Composion HD 172555: glassy silicas (Obsidian and TeK5te), steep grain size distribu5on with large quan55es of fine dust and possible fundamental and first overtone emission from SiO -> Hypervelocity Collision (Lisse, Chen et al. 2009) Eta Crv: warm, water- and carbon- rich dust in the terrestrial habitable zone -> Period of Late Heavy Bombardment (Lisse, Wya, Chen et al. 2012) • Typically well-fit assuming blacK • Typically includes silicates and trace bodies consistent with dust located in species indicang how processed parent rings (Jura et al. 2004, Chen et al. bodies are and therefore their origin 2006) (3) Dust Around Main Sequence A-Type Stars MIPS 24 and 70 μm observaons of 157 Harvard Review A- type stars with • Hipparcos distances < 80 pc • 0.0 > (B-V) > 0.2 mag • M(V) > 1.0 + 5.5 (B-V) Common Warm Dust Temperatures Around Main Sequence Stars • Includes IRS follow-up observaons of A-type stars with MIPS excess discovered in Jura and RieKe GTO programs Morales et al. (2011) Herschel Hints at Water Ice Morales et al. (2013) (4) The Fabulous Four Debris DisKs Collaborave GTO project to obtain mul5- instrument observaons of • β Pictoris led by IRS • ε Eridani led by IRAC • Fomalhaut led by General GTOs (Jura, Werner) • Vega led by MIPS Coordinated by Karl Stapelfeldt (JPL) ThanK you, MiKe… for mentoring and encouraging us, for generously sharing your personal 5me, your scien5fic ideas, and your observaons with us. Ray Jayawardhana Chrisne Chen Peter Plavchan PhD Harvard 2000 PhD UCLA 2002 PhD UCLA 2006 Farisa Morales Greg Sloan BS UCLA 2003 IRSDisKs .
Load more

Recommended publications
  • Exoplanet.Eu Catalog Page 1 # Name Mass Star Name
    exoplanet.eu_catalog # name mass star_name star_distance star_mass OGLE-2016-BLG-1469L b 13.6 OGLE-2016-BLG-1469L 4500.0 0.048 11 Com b 19.4 11 Com 110.6 2.7 11 Oph b 21 11 Oph 145.0 0.0162 11 UMi b 10.5 11 UMi 119.5 1.8 14 And b 5.33 14 And 76.4 2.2 14 Her b 4.64 14 Her 18.1 0.9 16 Cyg B b 1.68 16 Cyg B 21.4 1.01 18 Del b 10.3 18 Del 73.1 2.3 1RXS 1609 b 14 1RXS1609 145.0 0.73 1SWASP J1407 b 20 1SWASP J1407 133.0 0.9 24 Sex b 1.99 24 Sex 74.8 1.54 24 Sex c 0.86 24 Sex 74.8 1.54 2M 0103-55 (AB) b 13 2M 0103-55 (AB) 47.2 0.4 2M 0122-24 b 20 2M 0122-24 36.0 0.4 2M 0219-39 b 13.9 2M 0219-39 39.4 0.11 2M 0441+23 b 7.5 2M 0441+23 140.0 0.02 2M 0746+20 b 30 2M 0746+20 12.2 0.12 2M 1207-39 24 2M 1207-39 52.4 0.025 2M 1207-39 b 4 2M 1207-39 52.4 0.025 2M 1938+46 b 1.9 2M 1938+46 0.6 2M 2140+16 b 20 2M 2140+16 25.0 0.08 2M 2206-20 b 30 2M 2206-20 26.7 0.13 2M 2236+4751 b 12.5 2M 2236+4751 63.0 0.6 2M J2126-81 b 13.3 TYC 9486-927-1 24.8 0.4 2MASS J11193254 AB 3.7 2MASS J11193254 AB 2MASS J1450-7841 A 40 2MASS J1450-7841 A 75.0 0.04 2MASS J1450-7841 B 40 2MASS J1450-7841 B 75.0 0.04 2MASS J2250+2325 b 30 2MASS J2250+2325 41.5 30 Ari B b 9.88 30 Ari B 39.4 1.22 38 Vir b 4.51 38 Vir 1.18 4 Uma b 7.1 4 Uma 78.5 1.234 42 Dra b 3.88 42 Dra 97.3 0.98 47 Uma b 2.53 47 Uma 14.0 1.03 47 Uma c 0.54 47 Uma 14.0 1.03 47 Uma d 1.64 47 Uma 14.0 1.03 51 Eri b 9.1 51 Eri 29.4 1.75 51 Peg b 0.47 51 Peg 14.7 1.11 55 Cnc b 0.84 55 Cnc 12.3 0.905 55 Cnc c 0.1784 55 Cnc 12.3 0.905 55 Cnc d 3.86 55 Cnc 12.3 0.905 55 Cnc e 0.02547 55 Cnc 12.3 0.905 55 Cnc f 0.1479 55
    [Show full text]
  • High-Precision HST/WFC3/IR Time-Resolved Observations of Directly Imaged Exoplanet HD 106906B
    The Astronomical Journal, 159:140 (13pp), 2020 April https://doi.org/10.3847/1538-3881/ab6f65 © 2020. The American Astronomical Society. All rights reserved. Cloud Atlas: High-precision HST/WFC3/IR Time-resolved Observations of Directly Imaged Exoplanet HD 106906b Yifan Zhou1,2,15 , Dániel Apai1,3,4 , Luigi R. Bedin5, Ben W. P. Lew3 , Glenn Schneider1 , Adam J. Burgasser6 , Elena Manjavacas7 , Theodora Karalidi8 , Stanimir Metchev9,10 , Paulo A. Miles-Páez11,16 , Nicolas B. Cowan12 , Patrick J. Lowrance13 , and Jacqueline Radigan14 1 Department of Astronomy/Steward Observatory, The University of Arizona, 933 N. Cherry Avenue, Tucson, AZ 85721, USA; [email protected] 2 Department of Astronomy/McDonald Observatory, The University of Texas, 2515 Speedway, Austin, TX 78712, USA 3 Department of Planetary Science/Lunar and Planetary Laboratory, The University of Arizona, 1640 E. University Boulevard, Tucson, AZ 85718, USA 4 Earths in Other Solar Systems Team, NASA Nexus for Exoplanet System Science, USA 5 INAF—Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, I-35122 Padova, Italy 6 Center for Astrophysics and Space Science, University of California San Diego, La Jolla, CA 92093, USA 7 W.M. Keck Observatory, 65-1120 Mamalahoa Hwy. Kamuela, HI 96743, USA 8 Department of Physics, University of Central Florida, 4111 Libra Drive, Orlando, FL 32816, USA 9 Department of Physics & Astronomy and Centre for Planetary Science and Exploration, The University of Western Ontario, London, Ontario N6A 3K7, Canada 10 Department of Astrophysics,
    [Show full text]
  • Mid-IR Observations of Circumstellar Disks
    A&A 431, 175–182 (2005) Astronomy DOI: 10.1051/0004-6361:20041490 & c ESO 2005 Astrophysics Mid-IR observations of circumstellar disks II. Vega-type stars and a post-main sequence object O. Schütz1,G.Meeus2, and M. F. Sterzik3 1 Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany e-mail: [email protected] 2 Astrophysikalisches Institut Potsdam, An der Sternwarte 16, 14482 Potsdam, Germany 3 European Southern Observatory, Alonso de Cordova 3107, Santiago 19, Chile Received 18 June 2004 / Accepted 10 September 2004 Abstract. We present spectral energy distributions and new N-band photometry and spectroscopy for a sample of six main sequence stars and one post-MS object using the ESO TIMMI2 camera at La Silla observatory (Chile). All objects are thought to possess circumstellar material and for the majority of the targets this is their first N-band spectroscopic observation. The emission spectra (observed in three cases), modelled with a mixture of silicates consisting of different grain sizes and compo- sition, confirm the suspected presence of disks around these targets. The most important discovery is that HD 113766, a young Vega-type star, is host to highly processed dust which is probably second generation. It is the first time a Vega-type star with such highly evolved dust has been observed. Silicate emission of basically unevolved dust is seen in case of the post-MS object HD 41511 and the Vega-type star HD 172555. In addition, to study the cold dust, we observed a subsample at 1200 µm with the bolometer array SIMBA at the SEST in La Silla but we only got upper limits for those five objects.
    [Show full text]
  • The Co-Existence of Hot and Cold Gas in Debris Discs? I
    A&A 614, A3 (2018) https://doi.org/10.1051/0004-6361/201732329 Astronomy & © ESO 2018 Astrophysics The co-existence of hot and cold gas in debris discs? I. Rebollido1, C. Eiroa1, B. Montesinos2, J. Maldonado3, E. Villaver1, O. Absil4, A. Bayo5,6, H. Canovas1,7, A. Carmona8, Ch. Chen9, S. Ertel10, A. Garufi1, Th. Henning11, D. P. Iglesias5,6, R. Launhardt11, R. Liseau12, G. Meeus1, A. Moór13, A. Mora14, J. Olofsson5,6, G. Rauw4, and P. Riviere-Marichalar15 1 Departamento. Física Teórica, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain e-mail: [email protected] 2 Centro de Astrobiología (CAB, CSIC-INTA), ESAC Campus, Camino Bajo del Castillo s/n, Villanueva de la Cañada, 28692 Madrid, Spain 3 INAF, Osservatorio Astronomico di Palermo, Piazza del Parlamento 1, 90134 Palermo, Italy 4 STAR Institute, Université de Liège, F.R.S.-FNRS, 19c Allée du Six Août, 4000 Liège, Belgium 5 Instituto de Física y Astronomía, Facultad de Ciencias, Universidad de Valparaíso, Casilla, 5030 Valparaíso, Chile 6 Núcleo Milenio de Formación Planetaria-NPF, Universidad de Valparaíso, Av. Gran Bretaña, 1111 Valparaíso, Chile 7 European Space Astronomy Centre (ESA), PO Box 78, Villanueva de la Cañada, 28691 Madrid, Spain 8 Université de Toulouse, UPS-OMP, IRAP, 31400 Toulouse, France 9 Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21212, USA 10 Steward Observatory, Department of Astronomy, University of Arizona, Tucson, AZ 85721, USA 11 Max-Planck-Institut für Astronomie (MPIA), Königstuhl 17, 69117 Heidelberg, Germany 12 Department of Space, Earth and Environment, Chalmers University of Technology, Onsala Space Observatory, 439 92 Onsala, Sweden 13 Konkoly Observatory, Research Centre for Astronomy and Earth Sciences, PO Box 67, 1525 Budapest, Hungary 14 Aurora Technology B.V.
    [Show full text]
  • Exoplanet.Eu Catalog Page 1 Star Distance Star Name Star Mass
    exoplanet.eu_catalog star_distance star_name star_mass Planet name mass 1.3 Proxima Centauri 0.120 Proxima Cen b 0.004 1.3 alpha Cen B 0.934 alf Cen B b 0.004 2.3 WISE 0855-0714 WISE 0855-0714 6.000 2.6 Lalande 21185 0.460 Lalande 21185 b 0.012 3.2 eps Eridani 0.830 eps Eridani b 3.090 3.4 Ross 128 0.168 Ross 128 b 0.004 3.6 GJ 15 A 0.375 GJ 15 A b 0.017 3.6 YZ Cet 0.130 YZ Cet d 0.004 3.6 YZ Cet 0.130 YZ Cet c 0.003 3.6 YZ Cet 0.130 YZ Cet b 0.002 3.6 eps Ind A 0.762 eps Ind A b 2.710 3.7 tau Cet 0.783 tau Cet e 0.012 3.7 tau Cet 0.783 tau Cet f 0.012 3.7 tau Cet 0.783 tau Cet h 0.006 3.7 tau Cet 0.783 tau Cet g 0.006 3.8 GJ 273 0.290 GJ 273 b 0.009 3.8 GJ 273 0.290 GJ 273 c 0.004 3.9 Kapteyn's 0.281 Kapteyn's c 0.022 3.9 Kapteyn's 0.281 Kapteyn's b 0.015 4.3 Wolf 1061 0.250 Wolf 1061 d 0.024 4.3 Wolf 1061 0.250 Wolf 1061 c 0.011 4.3 Wolf 1061 0.250 Wolf 1061 b 0.006 4.5 GJ 687 0.413 GJ 687 b 0.058 4.5 GJ 674 0.350 GJ 674 b 0.040 4.7 GJ 876 0.334 GJ 876 b 1.938 4.7 GJ 876 0.334 GJ 876 c 0.856 4.7 GJ 876 0.334 GJ 876 e 0.045 4.7 GJ 876 0.334 GJ 876 d 0.022 4.9 GJ 832 0.450 GJ 832 b 0.689 4.9 GJ 832 0.450 GJ 832 c 0.016 5.9 GJ 570 ABC 0.802 GJ 570 D 42.500 6.0 SIMP0136+0933 SIMP0136+0933 12.700 6.1 HD 20794 0.813 HD 20794 e 0.015 6.1 HD 20794 0.813 HD 20794 d 0.011 6.1 HD 20794 0.813 HD 20794 b 0.009 6.2 GJ 581 0.310 GJ 581 b 0.050 6.2 GJ 581 0.310 GJ 581 c 0.017 6.2 GJ 581 0.310 GJ 581 e 0.006 6.5 GJ 625 0.300 GJ 625 b 0.010 6.6 HD 219134 HD 219134 h 0.280 6.6 HD 219134 HD 219134 e 0.200 6.6 HD 219134 HD 219134 d 0.067 6.6 HD 219134 HD
    [Show full text]
  • Exoplanetary Atmospheres
    Exoplanetary Atmospheres Nikku Madhusudhan1,2, Heather Knutson3, Jonathan J. Fortney4, Travis Barman5,6 The study of exoplanetary atmospheres is one of the most exciting and dynamic frontiers in astronomy. Over the past two decades ongoing surveys have revealed an astonishing diversity in the planetary masses, radii, temperatures, orbital parameters, and host stellar properties of exo- planetary systems. We are now moving into an era where we can begin to address fundamental questions concerning the diversity of exoplanetary compositions, atmospheric and interior processes, and formation histories, just as have been pursued for solar system planets over the past century. Exoplanetary atmospheres provide a direct means to address these questions via their observable spectral signatures. In the last decade, and particularly in the last five years, tremendous progress has been made in detecting atmospheric signatures of exoplanets through photometric and spectroscopic methods using a variety of space-borne and/or ground-based observational facilities. These observations are beginning to provide important constraints on a wide gamut of atmospheric properties, including pressure-temperature profiles, chemical compositions, energy circulation, presence of clouds, and non-equilibrium processes. The latest studies are also beginning to connect the inferred chemical compositions to exoplanetary formation conditions. In the present chapter, we review the most recent developments in the area of exoplanetary atmospheres. Our review covers advances in both observations and theory of exoplanetary atmospheres, and spans a broad range of exoplanet types (gas giants, ice giants, and super-Earths) and detection methods (transiting planets, direct imaging, and radial velocity). A number of upcoming planet-finding surveys will focus on detecting exoplanets orbiting nearby bright stars, which are the best targets for detailed atmospheric characterization.
    [Show full text]
  • Download This Article in PDF Format
    A&A 507, 261–276 (2009) Astronomy DOI: 10.1051/0004-6361/20066262 & c ESO 2009 Astrophysics Mid-IR observations of circumstellar disks Part III. A mixed sample of PMS stars and Vega-type objects O. Schütz1, G. Meeus2,M.F.Sterzik1, and E. Peeters3,4,5 1 European Southern Observatory, Alonso de Cordova 3107, Santiago 19, Chile e-mail: [email protected] 2 Astrophysikalisches Institut Potsdam, An der Sternwarte 16, 14482 Potsdam, Germany 3 NASA Ames Research Center, MS 245-6, Moffett Field, CA 94035, USA 4 SETI Institute, 515 N. Whisman Road, Mountain View, CA 94043, USA 5 The University of Western Ontario, London, ON N6A 3K7, Canada Received 18 August 2006 / Accepted 17 April 2009 ABSTRACT We present new mid-infrared spectra of 15 targets (1 FU Orionis object, 4 Herbig Ae stars, 5 T Tauri stars, and 5 Vega-type stars), obtained with the TIMMI2 camera at La Silla Observatory (ESO). Three targets are members of the β Pic moving group (HD 155 555, HD 181 296, and HD 319 139). PAH bands are observed towards the T Tauri star HD 34 700 and the Herbig Ae star PDS 144 N. For HD 34 700, the band profiles indicate processed PAHs. The spectrum of the Vega-type object η Corvi (HD 109 085), for which a resolved disk at sub-mm wavelengths is known, appears stellar between 8–13 μm, but a small excess emission was reported by Spitzer observations. Similarly, no indication of circumstellar matter at mid-infrared wavelengths is found towards the Vega-like stars HD 3003, HD 80 951, HD 181 296, and, surprisingly, the T Tauri system HD 155 555.
    [Show full text]
  • Arxiv:2108.13437V1 [Astro-Ph.EP] 30 Aug 2021 Perienced Giant Impacts, Tidal Friction, and Gravitational Forcing (E.G
    Draft version September 1, 2021 Typeset using LATEX twocolumn style in AASTeX631 Obliquity Constraints on the Planetary-mass Companion HD 106906 b Marta L. Bryan,1 Eugene Chiang,1 Caroline V. Morley,2 Gregory N. Mace,2 and Brendan P. Bowler2 1Department of Astronomy 501 Campbell Hall University of California Berkeley Berkeley, CA 94720-3411, USA 2Department of Astronomy The University of Texas at Austin Austin, TX 78712, USA ABSTRACT We constrain the angular momentum architecture of HD 106906, a 13 ± 2 Myr old system in the ScoCen complex composed of a compact central binary, a widely separated planetary-mass tertiary HD 106906 b, and a debris disk nested between the binary and tertiary orbital planes. We measure the orientations of three vectors: the companion spin axis, companion orbit normal, and disk normal. Using near-IR high-resolution spectra from Gemini/IGRINS, we obtain a projected rotational velocity of v sin ip = 9.5 ± 0.2 km/s for HD 106906 b. This measurement together with a published photometric rotation period implies the companion is viewed nearly pole-on, with a line-of-sight spin axis inclination ◦ ◦ of ip = 14 ± 4 or 166 ± 4 . By contrast, the debris disk is known to be viewed nearly edge-on. The likely misalignment of all three vectors suggests HD 106906 b formed by gravitational instability in a turbulent environment, either in a disk or cloud setting. Keywords: Exoplanet systems { Exoplanet formation { Exoplanet evolution { High resolution spec- troscopy { Astrostatistics 1. INTRODUCTION These processes and others can apply to exoplanets. Planetary obliquity measurements inform our under- Theoretical work shows that obliquities can be excited standing of how planets form and evolve.
    [Show full text]
  • Steady State Evolution of Debris Disks Around a Stars M
    The Astrophysical Journal, 663:365Y382, 2007 July 1 # 2007. The American Astronomical Society. All rights reserved. Printed in U.S.A. STEADY STATE EVOLUTION OF DEBRIS DISKS AROUND A STARS M. C. Wyatt Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK; [email protected] R. Smith Institute for Astronomy, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, UK K. Y. L. Su and G. H. Rieke Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 J. S. Greaves Scottish Universities Physics Alliance, University of St. Andrews, Physics and Astronomy, North Haugh, St. Andrews KY16 9SS, UK and C. A. Beichman1 and G. Bryden Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109 Received 2007 January 3; accepted 2007 March 22 ABSTRACT This paper confronts a simple analytical model for the steady state evolution of debris disks due to collisions with Spitzer observations of dust around main-sequence A stars. It is assumed that every star has a planetesimal belt, the initial mass and radius of which are drawn from distributions. In the model disk mass is constant until the largest plan- À1 etesimals reach collisional equilibrium, whereupon mass falls /tage. We find that the detection statistics and trends seen at 24 and 70 m can be fitted well by the model. While there is no need to invoke stochastic evolution or delayed stirring to explain the statistics, a moderate rate of stochastic events is not ruled out. Potentially anomalous systems are identified by a high dust luminosity compared with the maximum permissible in the model (HD 3003, HD 38678, HD 115892, HD 172555); their planetesimals may have unusual properties (high strength or low eccentricity), or this dust could be transient.
    [Show full text]
  • The Transinng Exocomets of HD 172555
    The Transi*ng Exocomets of HD 172555 C. A. Grady Eureka Scien*fic & GSFC In collaboraon with Alex Brown (Colorado), Inga Kamp and Pablo Riviere- Marichalar (Groningen), Aki Roberge (NASA’s GSFC), Barry Welsh (Eureka Scien*fic) 7/25/16 NCAD VI Talk Roadmap • Quick review of β Pic – protypical transi*ng exocomet system with disk and planet • HD 172555 - β Pic’s evil twin and its transi*ng exocomets • Implicaons for planet frequency and searches for addi*onal systems 7/25/16 NCAD VI I. Background - β Pic • A5V star (Teff=8100 ± 200 K) • Young moving group member (23 ± 3 Myr Mamajek & Bell 2014) • 2 component disk – outer disk at ~120 AU, viewed edge-on (Dent et al. 2014), inner disk to ~40 AU inclined by 5° with respect to the outer disk (Golimowski et al. 2006) • Gas: molecular, atomic and a range of ionizaon stages of abundant elements 7/25/16 NCAD VI The Case of β Pic • IR excess detected by IRAS • edge-on debris disk first imaged by Smith & Terrile 1984 • no variability over 15 years Apai + 15 7/25/16 NCAD VI • inner disk inclinaon with respect to outer disk is 5° (Golimowski et al. 2006) Edge-on Disk • Constrain locaon of planetesimal belt from mm imagery • Can locate or place upper limits on cold molecular gas • Co asymmetrically distributed • Pericenter offset seen with ALMA – indirect signature of planet(s) Dent+15 7/25/16 NCAD VI What we learn from Line of Sight UV Spectroscopy • Co absorp*on at system velocity Roberge + 2000 •N(H2)≤1E18 cm-2 Lecavelier des Etangs +01, Co/H2>6E-4 •low op*cal depth + radiaon field of star – life*me is
    [Show full text]
  • Detection of Scattered Light from the Hot Dust in HD 172555 ? ?? N
    Astronomy & Astrophysics manuscript no. HD172555_v7_arxiv c ESO 2018 August 15, 2018 Detection of scattered light from the hot dust in HD 172555 ? ?? N. Engler1, H.M. Schmid1, S.P. Quanz1, H. Avenhaus2, and A. Bazzon1 1 ETH Zurich, Institute for Particle Physics and Astrophysics, Wolfgang-Pauli-Strasse 27, CH-8093 Zurich, Switzerland e-mail: [email protected] 2 Max Planck Institute for Astronomy, Königstuhl 17, 69117 Heidelberg, Germany Received ...; accepted ... ABSTRACT Context. Debris disks or belts are important signposts for the presence of colliding planetesimals and, therefore, for ongoing planet formation and evolution processes in young planetary systems. Imaging of debris material at small separations from the star is very challenging but provides valuable insights into the spatial distribution of so-called hot dust produced by solid bodies located in or near the habitable zone. We report the first detection of scattered light from the hot dust around the nearby (d = 28:33 pc) A star HD 172555. Aims. We want to constrain the geometric structure of the detected debris disk using polarimetric differential imaging (PDI) with a spatial resolution of 25 mas and an inner working angle of about 0.100. Methods. We measured the polarized light of HD 172555, with SPHERE-ZIMPOL, in the very broad band (VBB) or RI filter 00 00 (λc = 735 nm, ∆λ = 290 nm) for the projected separations between 0:08 (2.3 au) and 0:77 (22 au). We constrained the disk parameters by fitting models for scattering of an optically thin dust disk taking the limited spatial resolution and coronagraphic attenuation of our data into account.
    [Show full text]
  • Astrotalk: Behind the News Headlines of May 2017
    AstroTalk: Behind the news headlines of May 2017 Richard de Grijs (何锐思) (Kavli Institute for Astronomy and Astrophysics, Peking University) Planetary formation is disks of dust and gas unveiled Newborn stars are typically located in disks of gas and dust. When planets first begin to form, rings of rocky and icy material (‘planetesimals’) form. The dust in those rings starts to stick together, growing until clumps develop that are large enough to attract other clumps because of their gravity. Astronomers believe that the process of forming planets and dissipating the disk takes about 10 million years. Many mysteries remain, however, including the tendency of dust not to stick together, and the likelihood that colliding clumps could break apart rather than agglomerate. As analogues to our own Solar System’s ‘Kuiper Belt’ or ‘Oort Cloud,’ the disks of debris left over from planet formation can be detected by astronomers and studied to help understand the processes that create planetary systems. Astronomers recently presented new observations of a nearby planetary system known as ‘61 Virginis’ (‘61 Vir’) and its debris disk. 61 Vir is a 4.6-billion-year- old star, about the size of our Sun, which is located approximately 28 light-years away. At least three planets orbit the parent star, which are five, 18, and 23 times more massive than the Earth. One of the most intriguing features of this system is its debris disk, which extends from 30 to at least 100 astronomical units (‘au,’ the average distance from the Sun to the Earth) from the star. A team of astronomers led by Sebastian Marino of the University of Cambridge (UK) has performed observations of 61 Vir’s debris disk using the Atacama Large Millimetre/submillimetre Array (ALMA) in Chile.
    [Show full text]