Exploring the giant planet - brown dwarf connection with astrometry ESA Research Fellow at ESAC Who s Who, Paris - 2 July 215
IS MASS A GOOD DEMOGRAPHIC INDICATOR? 2MASSWJ127334 393254 first image of a planetary mass companion in a different system than our own (Chauvin et al., A&A, 25) M 1 ~ 25 M Jup M 2 ~ 5 M Jup mass ratio q.2 778 mas 55 AU at 7 pc N E Planet masses and radii are difficult to measure (in nontransiting systems) N Astrometry gives a good handle on companion masses E 2
HIGH-MASS TAIL OF PLANET MASSES OVERLAPS WITH SUBSTELLAR COMPANIONS IN BINARY SYSTEMS J. Sahlm 15 J. Sahlmann et al.: Search for brown-dwarf companions of stars HD3277.. 2 radial velocity survey of 1647 GK dwarfs: 4 5 RV [m/s] RV [m/s] 1 discarded as M-dwarfs by Hipparcos.4.5 5.6.7 N 1 1.8.9 1..1..1.2.3.4 φ.. 5 astrometry (Sahlmann et al., 211, A&A, 525).3 5 2.2 1 1 2.1 M2 =.52 ±.5 M. M2 sin i = 49 ± 2 MJup 15 2 companions with M2 sin i = 13-8 MJup.1. HD17289 Δδ (mas). HD17289.5.6.7.8.9 1. 15 φ HD351..... +MIKE. HD43848 2 E 2 2 2 15 1 15 a).6 ±.2 % of Sun-like stars have a brown dwarf 5.1.2.3.4.5.6.7.8.9 1. HD52756.... b) no indication for discontinuity at 13 MJup 1 8 φ.. 4 2 Cumulative distribution companion within 1 AU.1. c) mass distribution indicates minimum occurrence RV [m/s] RV [m/s] 2 at ~25-45 MJup (see also Grether & Lineweaver 26) 4.8.1..1.2.3.4.5.6.7.8.9 1. HD5368 1 φ Giant Planets 2 Void...1..1.2.6.3.4.5.6.7.8.9 Orbital phase HD5368.4 Brown dwarf companions 5 1 6.2.1.2.3.4.5.6.7.8.9 1..1. 13 HD8977 φ.. HD7414.... 4 8.1.2.3.4.5.6.7.8.9 1. φ Δδ (mas) 15 8.1. 2 26 39 M2 sin i (MJ).. 52 65 78 3 4 4 2 3 2 V [m/s] V [m/s] 6 15 1 5 1 2 6 1 5 2 O C (mas) RV [m/s] RV [m/s] 1 Δα* (mas) 5 5 1 1.
WHAT IS THE PLANET MASS DISTRIBUTION AROUND ULTRACOOL DWARFS? Astrometric survey with FORS2 camera at VLT (Sahlmann et al. 214, Lazorenko et al. 214) Monitoring 2 nearby late-m and early-l dwarfs since 21 Long-term astrometic precision ~.1 milli-arcsec (Lazorenko et al. 29 & 211) sensitive down to Neptune-mass planets in ~1 day orbits 8 DE1157 48 (12) 6 δ (mas) 4 2 2 2 4 6 α* (mas) 8 1 12 6 DE1159 52 (13) DE1253 57 (14) 4 4
GIANT PLANETS ARE RARE AROUND ULTRACOOL DWARFS (AT ALL SEPARATIONS) Companion mass (M Jup ) 4 35 3 25 2 15 1 5 Separation (AU).6.19.44.8 1.36 companions excluded by data 1 1 365 2 Period (days) Less than 9 % of M8-L2 dwarfs have a giant planet >5MJup within.1-.8 AU (Sahlmann et al. 214) Ongoing follow-up of planet candidates 5
DETECTION OF THE ORBIT CAUSED BY A LOW- MASS COMPANION L1.5 dwarf P = 247.8 ±.6 days e =.36 ±.4 α = 4.62 ±.12 mas Parallax = 48.33 ±.14 mas 16 epochs residual RMS 17 µas Derived properties depend on age estimate Sahlmann et al., 213, A&A 556 6
A JUVENILE BINARY BROWN DWARF AT 2.7 PC Li I absorption detected in optical spectrum age constraint spectral binary in the near-infrared spectral types L1.5 + L5.5 Teff = 215 ± 1 K and 167 ± 14 K Normalized F λ 1.4 1.2 1..8.6.4.2 DENIS J823-4912 DENIS-P J17548.38-51645.7 L1.8 2MASS J22573-521524 L6.3:: χ 2 = 5.64.8.75.7.65 1.5 1.55 1.6 1.65 1.7 Wavelength (µm) Combined astrometric and spectroscopic constraints + evolutionary models: Age = 8-5 Myr M 1.28.63 M M 2.18.45 M mass ratio q.64.74 Sahlmann, Burgasser, et al. 215, A&A. 1. 1.2 1.4 1.6 1.8 2. 2.2 2.4 Wavelength (µm) Fig. 6. Results of spectrum fitting with binary templates (cf. Fig. 5). Top: When using all templates, the SpeX spectrum of DE823 49 (black line) is best fit by the binary template (brown line) that is a 7
A GIANT PLANET AROUND LUH16? WISE J14915.57-53196.1 (Luhman 213) 2 pc distance ~3 AU binary: L7.5 + T.5 (Burgasser et al. 213, Faherty et al. 214) Possible detection of a giant planet in a short-period orbit around one component (Boffin et al. 214) We analysed 22 epochs of public FORS2 data (PI: Boffin) taken over 1 year Applied Lazorenko s techniques to obtain astrometry of both components Individual fits are poor, data of both components have to be modelled jointly 8
BARYCENTRE FIT IS GOOD AND DETERMINES THE MASS RATIO ΔxB mass ratio q = MB / MA = ΔxA / ΔxB Reconstructed barycentre motion as a function of mass ratio: ΔxA? = = 1 1+q (? A + q B)? 1 ( 1+q A + q B ). q =.78 ±.1 ompanion aroun direct measurement (no models), independent of distance and orbit r.m.s. =.23 mas Sahlmann & Lazorenko, submitted, arxiv:156.7994 9
NO GIANT PLANET AROUND LUH16, YET companions excluded by data M A.6 M / M B.47 M (3 Gyr) M A.3 M / M B.23 M (.5 Gyr) Sahlmann & Lazorenko, submitted, arxiv:156.7994 1
GAIA S EXOPLANET AND BD YIELD 5-year all-sky survey, G < 2 mag Gaia will deliver high-precision astrometry of 1 million stars (+ photometry, spectroscopy) ESA Nominal mission began July 214 Gaia will discover thousands of giant extrasolar planets with masses higher than Saturn and periods shorter than ~2 days. (Casertano et al. 28, Sozzetti et al., 214, Perryman at al., 214, Sahlmann, Triaud & Martin 215) For Sun-like stars, Gaia astrometry will detect 3 MJup companions out to distances of ~.8 kpc and 6 MJup out to ~1.7 kpc Gaia will uniformly yield the masses and orbital parameters of hundreds of companions in the brown-dwarf mass range. 11
CONCLUSIONS Mass alone is not a good demographic indicator: A 35 MJup companion to a Sun-like star may have formed like a planet or like a binary. Astrometric surveys of ultracool dwarfs are sensitive to giant planets and reveal binaries with planetary-mass components. Super-Jupiters are rare at all separations. The mass ratio of the 2-pc binary brown dwarf LUH16 is.78 +/-.1. There is no indication for a giant planet in a short-period orbit around either component. Gaia s survey will provide a comprehensive census of substellar companions more massive than Saturn in the solar neighbourhood. Thanks to: P. Lazorenko (Kiev), E. Martín (Madrid) D. Ségransan, M. Mayor, D. Queloz, S. Udry & Geneva planet group A. Burgasser & D. Bardalez-Gagliuffi (San Diego) 12