Characterizing TW Hydra

At 60 pc, TW Hydra (TW Hya) is the closest example of a star with a gas-rich protoplanetary disk, though TW Hya may be relatively old (3-15 Myr). As such, TW Hya is especially appealing to test our understanding of the interplay between stellar and disk evolution. We present a high-resolution near-infrared spectrum of TW Hya obtained with the Immersion GRating INfrared Spectrometer (IGRINS) to re-evaluate the stellar parameters of TW Hya. We compare these data to synthetic spectra of magnetic stars produced by MoogStokes, and use sensitive spectral line profiles to probe the effective temperature, surface gravity, and magnetic field. A model with T_eff= 3800 K, log g=4.2, and B=3.0 kG best fits the near-infrared spectrum of TW Hya. These results correspond to a spectral type of M0.5 and an age of 8 Myr, which is well past the median life of gaseous disks.

[1]  L. Hillenbrand,et al.  AN OPTICAL SPECTROSCOPIC STUDY OF T TAURI STARS. I. PHOTOSPHERIC PROPERTIES , 2014, 1403.1675.

[2]  T. Barman,et al.  PHYSICAL PROPERTIES OF YOUNG BROWN DWARFS AND VERY LOW MASS STARS INFERRED FROM HIGH-RESOLUTION MODEL SPECTRA , 2009, 0911.3844.

[3]  M. Schwartz,et al.  Discovery of Seven T Tauri Stars and a Brown Dwarf Candidatein the Nearby TW Hydrae Association , 1998, astro-ph/9812189.

[4]  L. Hartmann,et al.  The Initial Mass Function in the Taurus Star-forming Region , 2002 .

[5]  A. Boss,et al.  NEW PARALLAXES AND A CONVERGENCE ANALYSIS FOR THE TW Hya ASSOCIATION , 2016, 1610.01667.

[6]  L. Testi,et al.  A photoevaporative gap in the closest planet-forming disc , 2016, 1609.03903.

[7]  L. Testi,et al.  An extensive VLT/X-shooter library of photospheric templates of pre-main sequence stars , 2017, 1705.10075.

[8]  A. Boss,et al.  DISTANCE AND KINEMATICS OF THE TW HYDRAE ASSOCIATION FROM PARALLAXES , 2012, 1211.2233.

[9]  W. Vacca,et al.  NEAR-INFRARED SPECTROSCOPY OF TW Hya: A REVISED SPECTRAL TYPE AND COMPARISON WITH MAGNETOSPHERIC ACCRETION MODELS , 2011, 1102.0535.

[10]  S. Alencar,et al.  Variability of Southern T Tauri Stars. II. The Spectral Variability of the Classical T Tauri Star TW Hydrae , 2002 .

[11]  W. Vacca,et al.  Accepted for publication in ApJ Preprint typeset using L ATEX style emulateapj v. 10/09/06 ATMOSPHERIC PARAMETERS OF FIELD L AND T DWARFS 1 , 2022 .

[12]  Kjell Eriksson,et al.  A grid of MARCS model atmospheres for late-type stars. I. Methods and general properties , 2008, 0805.0554.

[13]  C. Deen.  MODIFICATION OF THE MOOG SPECTRAL SYNTHESIS CODES TO ACCOUNT FOR ZEEMAN BROADENING OF SPECTRAL LINES , 2013, 1306.6625.

[14]  Observatoire de la Côte d'Azur,et al.  Gaia Data Release 1. Summary of the astrometric, photometric, and survey properties , 2016, 1609.04172.

[15]  Evidence for J- and H-band excess in classical T Tauri stars and the implications for disk structure and estimated ages , 2005, astro-ph/0509036.

[16]  Measuring Fundamental Parameters of Substellar Objects. I. Surface Gravities , 2004, astro-ph/0403265.

[17]  Geoffrey A. Blake,et al.  An old disk still capable of forming a planetary system , 2013, Nature.

[18]  D. Padgett,et al.  THE SPITZER c2d LEGACY RESULTS: STAR-FORMATION RATES AND EFFICIENCIES; EVOLUTION AND LIFETIMES , 2008, 0811.1059.

[19]  L. Testi,et al.  X-shooter spectroscopy of young stellar objects - III. Photospheric and chromospheric properties of Class III objects , 2013 .

[20]  J. Valenti,et al.  Measuring the Magnetic Field of the Classical T Tauri Star TW Hydrae , 2005, astro-ph/0509549.

[21]  Jeong-Yeol Han,et al.  Design and early performance of IGRINS (Immersion Grating Infrared Spectrometer) , 2014, Astronomical Telescopes and Instrumentation.

[22]  Paul M. Brunet,et al.  The Gaia mission , 2013, 1303.0303.

[23]  Julien H. Girard,et al.  Three Radial Gaps in the Disk of TW Hydrae Imaged with SPHERE , 2016, 1610.08939.

[24]  F. Allard,et al.  New evolutionary models for pre-main sequence and main sequence low-mass stars down to the hydrogen-burning limit , 2015, 1503.04107.

[25]  A. J. Weinberger,et al.  THE 0.5–2.22 μm SCATTERED LIGHT SPECTRUM OF THE DISK AROUND TW Hya: DETECTION OF A PARTIALLY FILLED DISK GAP AT 80 AU , 2013, 1306.2969.

[26]  D. James,et al.  Chemical abundances in six nearby star-forming regions. Implications for galactic evolution and plan , 2008, 0801.2529.

[27]  John T. Rayner,et al.  SpeX: A Medium‐Resolution 0.8–5.5 Micron Spectrograph and Imager for the NASA Infrared Telescope Facility , 2003 .

[28]  D. Padgett.  Atmospheric Parameters and Iron Abundances of Low-Mass Pre-Main-Sequence Stars in Nearby Star Formation Regions , 1996 .

[29]  J. Najita,et al.  Residual Gas and Dust around Transition Objects and Weak T Tauri Stars , 2017, 1701.06758.

[30]  W. Cochran,et al.  Kea: A New Tool to Obtain Stellar Parameters from Low to Moderate Signal-to-noise and High-resolution Echelle Spectra , 2016, 1604.08170.

[31]  Luca Ricci,et al.  RINGED SUBSTRUCTURE AND A GAP AT 1 au IN THE NEAREST PROTOPLANETARY DISK , 2016, 1603.09352.

[32]  K. Covey,et al.  FIRST MAGNETIC FIELD DETECTION ON A CLASS I PROTOSTAR , 2009, 0905.4784.

[33]  D. Queloz,et al.  TW Hydrae: evidence of stellar spots instead of a Hot Jupiter , 2008, 0808.2386.

[34]  In-Soo Yuk,et al.  300 nights of science with IGRINS at McDonald Observatory , 2016, Astronomical Telescopes + Instrumentation.

[35]  D. Broguiere,et al.  THE 2014 ALMA LONG BASELINE CAMPAIGN: FIRST RESULTS FROM HIGH ANGULAR RESOLUTION OBSERVATIONS TOWARD THE HL TAU REGION , 2015 .

[36]  Charles J. Lada,et al.  THE AGE, STELLAR CONTENT, AND STAR FORMATION TIMESCALE OF THE B59 DENSE CORE , 2010, 1007.2192.

[37]  Jonathan P. Williams,et al.  Protoplanetary Disks and Their Evolution , 2011, 1103.0556.

[38]  S. Ida,et al.  A GAP WITH A DEFICIT OF LARGE GRAINS IN THE PROTOPLANETARY DISK AROUND TW Hya , 2016, 1605.00289.

[39]  D. T. Jaffe,et al.  A Spectroscopic Technique for Measuring Stellar Properties of Pre-Main-Sequence Stars , 2003, astro-ph/0308521.

[40]  A. Krone-Martins,et al.  The TW Hydrae association: trigonometric parallaxes and kinematic analysis ? , 2014, 1401.1935.

[41]  R. Doyon,et al.  BANYAN. IV. FUNDAMENTAL PARAMETERS OF LOW-MASS STAR CANDIDATES IN NEARBY YOUNG STELLAR KINEMATIC GROUPS—ISOCHRONAL AGE DETERMINATION USING MAGNETIC EVOLUTIONARY MODELS , 2014, 1406.6750.

[42]  Konstantin Grankin,et al.  Placing the Spotted T Tauri Star LkCa 4 on an HR Diagram , 2017, 1701.06703.