Lithium abundances of very low mass members of Chamaeleon I

Details Lithium abundances of very low mass members of Chamaeleon I Lithium abundances of very low mass members of Chamaeleon I

Nov 2007

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2007a%26a...475..667j&link_type=abstract

Astronomy and Astrophysics, Volume 475, Issue 2, November IV 2007, pp.667-675

Astronomy and Astrophysics

Astrophysics

4

Stars: Atmospheres, Line: Profiles, Stars: Low-Mass, Brown Dwarfs, Stars: Pre-Main Sequence, Ism: Individual Objects: Chamaeleon I

Scientific paper

Aims:We present the first study of the lithium abundances of very low mass objects in Chamaeleon I close to the hydrogen burning mass limit based on atmospheric models and high-resolution spectroscopic observations. The studied objects, Cha Hα 2, 3, 4, 5, 6 and 8, are very young brown dwarf candidates and very low mass stars on the verge of lithium depletion. Methods: For this analysis, we have computed a new “GAIA-cond” class model grid over effective temperatures from 2600 K to 3100 K, surface gravities from log(g) = 3.5 to 5.5, and lithium abundances from logɛ = 0.0 to 3.7, for two different line profile setups introduced in previous work. Calculated synthetic spectra are compared with high-resolution UVES / VLT echelle spectra of the objects. Results: We find good descriptions of the lithium resonance doublet lines at 6708 Å and of the surrounding pseudo-continuum and determine a consistent set of lithium abundances (log(ɛ) = 1.55). However, the derived lithium abundances are lower than the meteoritic one (log(ɛ) = 3.31) and that of higher mass stars in Cha I (log(ɛ) = 3.1/3.4 for LTE-/non-LTE-calculations). By modeling the TiO-line, we demonstrate that veiling does not make the lithium lines appear weaker. We can also rule out that the results are spoiled by the presence of spots. Conclusions: A possible explanation for these results would be that the objects are either more massive, or much older, than previously thought, so that the lithium depletion has already started. Although the uncertainties of the masses and ages are large, they are not large enough as to explain the observed lithium depletion. Therefore, the most likely explanation is either a lack of understanding of the details of the formation of the lithium line, or a lack of understanding of the internal structure of the very young low-mass objects.
Based on observations obtained at the European Southern Observatory at Paranal, Chile in program 65.L-0629(A,B) and 65.I-0011(A).

Affiliated with

Also associated with

No associations

Rating

Lithium abundances of very low mass members of Chamaeleon I does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Lithium abundances of very low mass members of Chamaeleon I, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Lithium abundances of very low mass members of Chamaeleon I will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1695803