| Issue |
A&A
Volume 463, Number 1, February III 2007
|
|
|---|---|---|
| Page(s) | 309 - 313 | |
| Section | Stellar structure and evolution | |
| DOI | https://doi.org/10.1051/0004-6361:20066463 | |
| Published online | 02 January 2007 | |
Near-infrared integral-field spectroscopy of the companion to GQ Lupi*
1
European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching, Germany e-mail: andreas.seifahrt@eso.org
2
Astrophysikalisches Institut, Universität Jena, Schillergässchen 2-3, 07745 Jena, Germany
3
Hamburger Sternwarte, Gojenbergsweg 112, 21029 Hamburg, Germany
Received:
28
September
2006
Accepted:
7
December
2006
Context.The first substellar companion of possibly planetary mass around a normal star, GQ Lup, has been directly imaged (Neuhäuser et al. 2005, A&A, 435, L13). Besides the unknown formation history, the mass of such an object is a criterion to decide about its true nature.
Aims.We aim to determine the physical properties of
the GQ Lup companion
– effective temperate (Teff) and surface gravity (
),
and thus its mass independently from evolutionary models.
Methods.We use the adaptive optics integral-field spectrograph SINFONI at the VLT for near-infrared
spectroscopy from 1.1 to 2.5 
m with a resolution of 
–4000.
We compare these spectra with synthetic atmospheric models (GAIA v2.0 cond).
Results.From the complete set of spectra we find a consistent effective temperature and surface gravity of
and 
.
Combined with a slightly revised luminosity of 
dex
for the companion, we determine a radius of 
and thus a mass of ~
. The uncertainty of this value is rather high.
Due to the large uncertainty of the surface gravity, the mass could range from 4 to 155 
.
By comparing the paramaters of the companion of GQ Lup to the ones of 2MASS J05352184-0546085, published by Stassun et al. (2006, Nature, 440, 311), we conclude that the companion to GQ Lup A has a mass lower than
.
Key words: stars: low-mass, brown dwarfs / planetary systems / techniques: spectroscopic
© ESO, 2007
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