Astron. Astrophys. 363, L25-L28 (2000)

Letter to the Editor

A young stellar group associated with HD 199143 (d = 48 pc) ^*

M.E. van den Ancker ^1,2, M.R. Pérez ³, D. de Winter ^4,5 and B. McCollum <sup>6

1</sup> University of Amsterdam, Astronomical Institute "Anton Pannekoek", Kruislaan 403, 1098 SJ Amsterdam, The Netherlands
² Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MS 42, Cambridge MA 02138, USA
³ Emergent-IT Corp., 9315 Largo Drive West, Suite 250, Largo MD 20774, USA
⁴ Instituto de Astrofísica de Canarias, C/ Via Láctea s/n, 38200 La Laguna, Tenerife, Spain
⁵ TNO-TPD, Stieltjesweg 1, P.O. Box 155, 2600 AD Delft, The Netherlands
⁶ IPAC-Caltech, SIRTF Science Center, MS 314-6, Pasadena, CA 911125, USA

Received 17 October 2000 / Accepted 2 November 2000

Abstract

We present new optical and ultraviolet spectroscopy of the anomalous EUV emitter HD 199143 (F8V). High resolution spectra in the H and Na I D wavelength regions show evidence for very rapid (a few hundred km s^-1) rotation of the stellar photosphere. Using archive IRAS data we also show that the star has excess emission above photospheric levels at 12 µm. IUE data of HD 199143 reveal the presence of emission lines of Mg II , C I , C II , C III , C IV , Si IV , He II and N V and show a large variability, both in the continuum and line fluxes. We propose that all available data of HD 199143 can be explained by assuming that is has been spun up by accretion of material from a close T Tauri like companion, responsible for the emission lines, the ultraviolet variability and the excess infrared emission. The bursting or flaring nature of this object, mostly in high energies, could be explained as episodic mass transfer between the star and its close companion. We show that HD 199143 and the Li-rich late-type dwarf BD-17^o6128 form a physical pair and suggest that both may be part of a new nearby (48 pc) young ( 10⁷ yr) stellar association in Capricornius.

Key words: stars: individual: HD 199143 stars: peculiar stars: rotation Galaxy: open clusters and associations: general ultraviolet: stars

* Based on observations collected at the European Southern Observatory, La Silla, Chile, observations made by IUE at NASA-GSFC, and with the Isaac Newton Telescope operated on the island of La Palma by the Isaac Newton Group in the Spanish Observatorio del Roque de los Muchachos

Send offprint requests to: M.E. van den Ancker (mario@astro.uva.nl)

© European Southern Observatory (ESO) 2000

Online publication: December 11, 2000

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