Volume 590, June 2016
|Number of page(s)||8|
|Section||Stellar structure and evolution|
|Published online||19 May 2016|
An M-dwarf star in the transition disk of Herbig HD 142527
Physical parameters and orbital elements
1 LESIA/Observatoire de Paris, PSL, CNRS, UPMC, Université Paris Diderot, 5 place Jules Janssen, 92195 Meudon, France
2 Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, UK
3 Institute for Astronomy, University of Edinburgh, Blackford Hill View, Edinburgh EH9 3HJ, UK
4 Observatoire de Genève, Université de Genève, 51 chemin des Maillettes, 1290 Versoix, Switzerland
5 Johns Hopkins University, Department of Physics and Astronomy, 3400 N. Charles St., Baltimore, MD 21218, USA
6 Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge, CB3 0HA, UK
7 Sydney Institute for Astronomy, School of Physics, University of Sydney, NSW 2006, Australia
8 Space Telescope Science Institute, 3700 San Martin Drive, Baltimore MD 21218, USA
9 Astrophysics Group, School of Physics, University of Exeter, Exeter EX4 4QL, UK
10 European Southern Observatory, Alonso de Cordova 3107, Casilla 19001, Santiago, Chile
11 Univ. Grenoble Alpes, CNRS, IPAG – UMR 5274, 38000 Grenoble, France
12 École Normale Supérieure, Lyon, CRAL (UMR CNRS 5574), Université de Lyon 1, 69007 Lyon, France
13 Max Planck Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
14 Instituto de Física y Astronomía, Universidad de Valparaíso, Av. Gran Bretaña 1111, Playa Ancha, Valparaíso, Chile
15 ICM nucleus on protoplanetary disks, Universidad de Valparaíso, Av. Gran Bretaña 1111, Valparaíso, Chile
16 School of Physics and Astronomy, University of St Andrews, North Haugh, KY16 6SS, St Andrews, UK
17 Gemini Observatory, Casilla 603, La Serena, Chile
18 Gemini Observatory, 670 North A’ohoku Place, Hilo, HI 96720, USA
19 Durham University, Stockton Road, Durham, DH1 3LE, UK
20 Astronomy Department, University of California, Berkeley CA 94720, USA
21 Large Synoptic Survey Telescope, 950N Cherry Av, Tucson AZ 85719, USA
22 Center for Astrophysics and Space Science, University of California San Diego, La Jolla, CA 92093, USA
23 Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, Stanford, CA 94305, USA
24 Department of Astrophysics, American Museum of Natural History, New York, NY 10024, USA
25 NASA/Armstrong Flight Research Center, 2825 East Avenue P, Palmdale, CA 93550, USA
Received: 30 November 2015
Accepted: 25 April 2016
Aims. HD 42527A is one of the most studied Herbig Ae/Be stars with a transitional disk, as it has the largest imaged gap in any protoplanetary disk: the gas is cleared from 30 to 90 AU. The HD 142527 system is also unique in that it has a stellar companion with a small mass compared to the mass of the primary star. This factor of ≈20 in mass ratio between the two objects makes this binary system different from any other YSO. The HD 142527 system could therefore provide a valuable test bed for understanding the impact of a lower mass companion on disk structure. This low-mass stellar object may be responsible for both the gap and dust trapping observed by ALMA at longer distances.
Methods. We observed this system with the NACO and GPI instruments using the aperture masking technique. Aperture masking is ideal for providing high dynamic range even at very small angular separations. We present the spectral energy distribution (SED) for HD 142527A and B. Brightness of the companion is now known from the R band up to the M′ band. We also followed the orbital motion of HD 142527B over a period of more than two years.
Results. The SED of the companion is compatible with a T = 3000 ± 100 K object in addition to a 1700 K blackbody environment (likely a circum-secondary disk). From evolution models, we find that it is compatible with an object of mass 0.13 ± 0.03 M⊙, radius 0.90 ± 0.15 R⊙, and age 1.0+1.0-0.75 Myr. This age is significantly younger than the age previously estimated for HD 142527A. Computations to constrain the orbital parameters found a semimajor axis of 140+120-70 mas, an eccentricity of 0.5 ± 0.2, an inclination of 125 ± 15 degrees, and a position angle of the right ascending node of −5 ± 40 degrees. Inclination and position angle of the ascending node are in agreement with an orbit coplanar with the inner disk, not coplanar with the outer disk. Despite its high eccentricity, it is unlikely that HD 142527B is responsible for truncating the inner edge of the outer disk.
Key words: protoplanetary disks / planet-disk interactions / binaries: visual / stars: variables: T Tauri, Herbig Ae/Be
© ESO, 2016
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