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Direct Imaging of Exoplanets: Exploring the Youngest Ages of Discovery

Discovering exoplanets in star-forming regions of Chamaeleon using VLT/FORS1. Observations of brown dwarfs and stellar formation, common proper motion analysis, and characteristics of CT Cha b. This press release outlines findings, measurements, and possible implications for the formation of exoplanets.

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Direct Imaging of Exoplanets: Exploring the Youngest Ages of Discovery

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  1. Direct Imaging of exoplanets at their youngest agesTobias Schmidt

  2. ESO press release 1640

  3. Star-forming regions of Chamaeleon ESO: VLT / FORS1 CHXR 32 • 3 dark clouds Cha I, II und III • Distance 160 – 180 pc* • Cha I with 33 Brown dwarfs of approx. 240 members and 2 million years age • Cha II approx. 50 members • Cha III only few hints of stellar formation (Pfau et al. 1996) DSS Dobashi et al. 2005 DI Cha DSS Sz 22 HD 97048 Cha Ha 5 Luhman et al. 2008 Cederblad 111 reflection nebula * Parsec: 1 pc = 3.26 light years = 3.086 .1016 m

  4. CT Cha: Classical T Tauri star in Chamaeleon star-forming region • cc 2 is a background object, spectral type < K4 at > 350 pc • cc1: J - Ks = 1.66 mag  spectral type L0 – L5 cc 1 cc 2 companion ! Schmidt, Neuhäuser, Seifahrt, Vogt et al. 2008 A&A

  5. CT Cha common proper motion analysis Separation = 2.67 arcsec 440 AUa at 165 pcb Common proper motion !  0.99 ± 1.73 mas / yr change in separation 6 σ 6 σ 2009 2006 2007 a 1 AU = 1.5 .1011 m b 1 pc = 3.26 Lichtjahre = 3 .1016 m Schmidt, Neuhäuser, Seifahrt, Vogt et al. 2008 A&A

  6. CT Cha common proper motion 2006 2007 2009 2 σ 2 σ -0.03 + / - 0.06 °/ yr Position angle change Schmidt, Neuhäuser, Seifahrt, Vogt et al. 2008 A&A

  7. CT Cha b and Drift-Phoenix: T= 2600 K ± 250 K AV= 5.2 ± 0.8 mag Mag, AV and distance give luminosity L (log(L/Lsun)= -2.68 ± 0.21) L and T give radius (~ 2.2 ± 0.7 R_Jup) T, L, age give mass: ~ 17 ± 6 M_Jup but model-dependant (planet or BD ?) J H K Drift-Phoenix: Helling et al. 2008 Schmidt, Neuhäuser, Seifahrt et al. 2008 A&A

  8. CT Cha b and Drift-Phoenix: T= 2600 K ± 250 K AV= 5.2 ± 0.8 mag Mag, AV and distance give luminosity L (log(L/Lsun)= -2.68 ± 0.21) L and T give radius (~ 2.2 ± 0.7 R_Jup) T, L, age give mass: ~ 17 ± 6 M_Jup but model-dependant (planet or BD ?) J H K CT Cha AV= 5.2 mag UScoJ160714-232101 AV= 2.1 mag Lodieu et al. 2008 Schmidt, Neuhäuser, Seifahrt et al. 2008 A&A

  9. CT Cha observation log

  10. J J K I K I H H 1800 K, log g 5.0, AV = 0.1 mag 2600 K, log g 3.5, AV = 5.2 mag K K Drift-Phoenix: Helling et al. 2008 Two possible solutions – new preliminary estimates of temperature in the middle

  11. Witte et al. 2011 – Comparison with the 108 suited (e.g. single) BDs from DwarfArchives DH Tau b – Itoh et al. (2005) Models by Tsuji et al. (2004)

  12. CT Cha b Béjar et al. 2008 Mass with and without the extinction different

  13. VO UScoCTIO 108 b ~ 5 -- 11 Myr K I K I Pa β accretion! Pa β VO CT Cha b ~ 2 Myr K I K I

  14. Mag AO observations of CT Cha (Wu et al. 2015)

  15. Mag AO observations of CT Cha (Wu et al. 2015) Strong Hα (20 sigma) accretion

  16. FORS2 observations of CT Cha R Special I Bessel Z Gunn

  17. LkCA 15 upper limit CT Cha Strong accretion

  18. Disk around CT Cha A ATCA New Detection of CT Cha at ATCA in 3 mm (93 & 95 GHz), 7.2 mJy total, 5 mJy in Maximum

  19. Disk around CT Cha A

  20. Disk around CT Cha A For k = 0.3 to 3 cm^2 / g and mean disk temperature of 20 – 50 K the disk mass is 0.1 – 1 Jupiter mass Deconvolution of the marginal extended gaussian-shaped 3mm source in comparison to synthesized beam size suggests an outer disk radius of 100 – 150 au.

  21. butterfly pattern i ~40-50° East-West

  22. CT Cha A: DOLP: 1.45 % AOLP: 124.9° CT Cha companion: DOLP: 0.67 +/- 0.16 % AOLP: 93.2 +/- 6.6° (Bright. Pix.: ~60°) Background star: DOLP: 1.3 +/- 0.3 AOLP: 99.5° (Bright. Pix.: ~125°) • CT Cha A diskclearlydetected • Background starpossiblycontaminatedby stellar • light polarization

  23. Disk around CT Cha companion ? optimization on electric field rather than intensity Assumption: no polarization around primary star sub-stellar companion: 272 counts (total int.) and 8.66 counts pol. (3%) background star: 71 counts (total int.) and limited by 1% noise for pol.

  24. Summary • So farwecanprovide: • New massestimatefromlongerwavelengthcoverage (+ opticalto Y band) givespreliminarily 12 Mjup • Strong accretionfromPaβ and H αdetected • Detectionofprimarydisk (confirmed last monthby ALMA (seebelow) ) • Tentative detectionofdiskaroundcompanionby 32 min obser-vationunderunstableconditions • System withtwodisks, massratio about 0.01, but 440 AU.  howdidit form? CT Cha Covino et al. 1997 polarization map

  25. ALMA observations of CT Cha (Wu et al. 2017) Follow-up information of confirmed disk by JWST/MIRI possible!

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