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|Title:||Spectro-astrometry of LkCa 15 with X-Shooter: Searching for emission from LkCa 15b||Authors:||Whelan, E. T.
ALCALA', JUAN MANUEL
|Issue Date:||2015||Journal:||ASTRONOMY & ASTROPHYSICS||Number:||579||First Page:||A48||Abstract:||Planet formation is one explanation for the partial clearing of dust observed in the disks of some T Tauri stars. Indeed studies using state-of-the-art high angular resolution techniques have very recently begun to observe planetary companions in these so-called transitional disks. The goal of this work is to use spectra of the transitional disk object LkCa 15 obtained with X-Shooter on the Very Large Telescope to investigate the possibility of using spectro-astrometry to detect planetary companions to T Tauri stars. It is argued that an accreting planet should contribute to the total emission of accretion tracers such as Hα and therefore planetary companions could be detected with spectro-astrometry in the same way as it has been used to detect stellar companions to young stars. A probable planetary-mass companion was recently detected in the disk of LkCa 15. Therefore, it is an ideal target for this pilot study. We studied several key accretion lines in the wavelength range 300 nm to 2.2 μm with spectro-astrometry. While no spectro-astrometric signal is measured for any emission lines, the accuracy achieved in the technique is used to place an upper limit on the contribution of the planet to the flux of the Hα, Paγ, and Paβ lines. The derived upper limits on the flux allow an upper limit of the mass accretion rate, log (Ṁ<SUB>acc</SUB>) = -8.9 to -9.3 for the mass of the companion between 6 M<SUB>Jup</SUB> and 15 M<SUB>Jup</SUB>, respectively, to be estimated (with some assumptions). <P />Based on Observations collected with X-Shooter at the Very Large Telescope on Cerro Paranal (Chile), operated by the European Southern Observatory (ESO). Program ID: 288.C-5013(A).||Acknowledgments:||We thank the referee M. Takami for his very helpful comments. We thank P. Goldoni for discussions on the aliasing problems in long-slit spectroscopy in general and for X-Shooter in particular. We thank S. Moehler, V. D’Oricio, P. Goldoni and A. Modigliani for their help with the X-Shooter pipeline, and F. Getman and G. Capasso for the installation of the different pipeline versions at Capodimonte. We acknowledge support from the Faculty of the European Space Astronomy Centre (ESAC). E.T. Whelan acknowledges financial support from the Deutsche Forschungsgemeinschaft through the Research Grant Wh 172/1-1. This research has also been funded by Spanish grant AYA2012-38897-C02-01. J.M. Alcalá acknowledges financial support from the PRIN INAF 2013 Disks, jets and the dawn of planets.||URI:||http://hdl.handle.net/20.500.12386/23171||URL:||https://www.aanda.org/articles/aa/abs/2015/07/aa25578-14/aa25578-14.html||ISSN:||0004-6361||DOI:||10.1051/0004-6361/201425578||Bibcode ADS:||2015A&A...579A..48W||Fulltext:||open|
|Appears in Collections:||1.01 Articoli in rivista|
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