Looper, Dagny L. and Mohanty, Subhanjoy and Bochanski, John J. and Burgasser, Adam J. and Mamajek, Eric E. and Herczeg, Gregory J. and West, Andrew A. and Faherty, Jacqueline K. and Rayner, John and Pitts, Mark A. and Kirkpatrick, J. Davy (2010) The Enigmatic Young, Low-mass Variable TWA 30. Astrophysical Journal, 714 (1). pp. 45-67. ISSN 0004-637X http://resolver.caltech.edu/CaltechAUTHORS:20100610-090727216
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TWA 30 is a remarkable young (7 ± 3 Myr), low-mass (0.12 ± 0.04M_⊙), late-type star (M5 ± 1) residing 42 ± 2 pc away from the Sun in the TW Hydrae Association (TWA). It shows strong outflow spectral signatures such as [S ii], [O i], [O ii], [O iii], and Mgi], while exhibiting weak Hα emission (−6.8±1.2 Å). Emission lines of [S ii] and [O i] are common to T Tauri stars still residing in their natal molecular clouds, while [O iii] and Mgi] emission lines are incredibly rare in this same population; in the case of TWA 30, these latter lines may arise from new outflow material colliding into older outflow fronts. The weak Hα emission and small radial velocity shifts of line emission relative to the stellar frame of rest (generally ≾10 km s^(−1)) suggest that the disk is viewed close to edge-on and that the stellar axismay be inclined to the disk, similar to the AA Tau system, based on its temporal changes in emission/ absorption line strengths/profiles and variable reddening (A_V = 1.5–9.0). The strong Li absorption (0.61 ± 0.13 Å) and common kinematics with members of the TWA confirm its age and membership to the association. Given the properties of this system such as its proximity, low mass, remarkable outflow signatures, variability, and edge-on configuration, this system is a unique case study at a critical time in disk evolution and planet-building processes.
|Additional Information:||© 2010 The American Astronomical Society. Received 2009 October 23; accepted 2010 February 9; published 2010 April 7. This paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile. We thank our anonymous referee whose comments improved the quality of this paper. We thank George Herbig, Mike Cushing, Nathan Smith, Silvia Alencar, Silvie Cabrit, Bo Reipurth, Klaus Hodapp, Brendan Bowler, Kevin Covey, George Wallerstein, and Suzanne Hawley for useful discussions. We also thank our telescope operators at Magellan: Mauricio Martinez, Hern´an Nu˜nez, and Ricardo Covarrubias, and at IRTF: Paul Sears, Bill Golisch, and Dave Griep. D.L.L. thanks Dave Sanders and George Herbig for financial support. This research has benefitted from the M, L, and T dwarf compendium housed at DwarfArchives.org and maintained by Chris Gelino, J. Davy Kirkpatrick, and Adam Burgasser. This research has made use of the Atomic Line List v2.04 maintained at http://www.pa.uky.edu/∼peter/atomic/; the SIMBAD database and VizieR catalog access tool, operated at CDS, Strasbourg, France; and the facilities of the Canadian Astronomy Data Centre operated by the National Research Council of Canada with the support of the Canadian Space Agency. This paper uses data from the IRTF Spectral Library (http://irtfweb.ifa.hawaii.edu/∼spex/IRTF_Spectral_Library/ index.html) maintained by John Rayner, Michael Cushing, and William Vacca. This publication makes use of data products from the Two Micron All Sky Survey, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology, funded by the National Aeronautics and Space Administration and the National Science Foundation. This research has made use of the NASA/IPAC Infrared Science Archive, which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. As some spectroscopic follow-up data were obtained from the summit of Mauna Kea, the authors wish to recognize and acknowledge the very significant and cultural role and reverence that this mountaintop has always had with the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations there.|
|Subject Keywords:||brown dwarfs – circumstellar matter – open clusters and associations: individual (TW Hydrae Association) – stars: evolution – stars: individual (2MASS J11321831 −3019518, TWA 30) – stars: low-mass – stars: pre-main-sequence|
|Classification Code:||PACS: 98.20.Bg; 97.10.Ex; 97.10.Ri; 97.10.Fy; 98.58.Db; 97.20.Jg.|
|Official Citation:||Dagny L. Looper et al 2010 ApJ 714 45 doi: 10.1088/0004-637X/714/1/45|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Tony Diaz|
|Deposited On:||13 Jun 2010 03:38|
|Last Modified:||26 Dec 2012 12:07|
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