相关论文: Lithium in LP 944-20

A spectroscopic investigation of the lithium resonance doublet in $\xi$ Boo A and $\xi$ Boo B in terms of both abundance and isotopic ratio is presented. We obtained new $R$=130\,000 spectra with a signal-to-noise ratio (S/N) per pixel of…

The bulk abundances of exoplanetesimals can be measured when they are accreted by white dwarfs. Recently, lithium from the accretion of exoplanetesimals was detected in relatively high levels in multiple white dwarfs. There are presently…

Lithium is a fragile but crucial chemical element in the universe, exhibits interesting and complex behaviors. Thanks to the massive spectroscopic data from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST)…

Accurately known stellar lithium abundances may be used to shed light on a variety of astrophysical phenomena such as Big Bang nucleosynthesis, radial migration, ages of stars and stellar clusters, and planet engulfment events. We present a…

We present JHKs photometry, far red spectra, and spectral classifications for an additional 67 L dwarfs discovered by the Two Micron All Sky Survey. One of the goals of this new search was to locate more examples of the latest L dwarfs. Of…

We present a complete line list for the X 1Sigma+ electronic ground state of LiCl computed using fully quantum-mechanical techniques. This list includes transition energies and oscillator strengths in the spectral region 0.3-39,640.7 cm-1…

We perform non-LTE calculations of lithium in late-type stars for a wide range of stellar parameters, including quantum mechanical cross-sections for collisions with neutral hydrogen and the negative hydrogen ion. Non-LTE abundance…

Detailed simultaneous radiative transfer-statistical equilibrium calculations have been performed for lithium in atmospheres of solar metallicity G-M dwarfs and subgiants. Model atmospheres of stars with $3500 \le \Tf \le 6000$ K, $3.0 \le…

We present high angular resolution, near-infrared imaging and spectroscopy of a low-mass companion to the lithium-depleted, double-line spectroscopic binary HBC 425 (St 34) obtained using the Near Infrared Spectrograph (NIRSPEC) and the…

We present intermediate- and low-resolution optical spectra around Halpha and LiI 6708 A for a sample of 25 low mass stars and 2 brown dwarfs with confirmed membership in the pre-main sequence stellar sigma Orionis cluster. Our observations…

We derive atmospheric parameters and lithium abundances for 671 stars and include our measurements in a literature compilation of 1381 dwarf and subgiant stars. First, a "lithium desert" in the effective temperature (Teff) versus lithium…

A reliable age estimation for the field brown dwarf LP 944-20 is accomplished through the analysis of its kinematic properties. The space velocities of this star strongly suggest its membership in the so-called Castor moving group. LP…

We present JWST/MIRI low-resolution spectroscopy ($4.75-14~\mu$m) of the first known substellar companion, Gliese 229 Bab, which was recently resolved into a tight binary brown dwarf. Previous atmospheric retrieval studies modeling Gliese…

We present results from a two-night R~4000 0.9-2.5 micron spectroscopic monitoring campaign of Luhman 16AB (L7.5 + T0.5). We assess the variability amplitude as a function of pressure level in the atmosphere of Luhman 16B: the more variable…

Observations are presented which show that LiI 6708A is detected with equivalent width of 0.53+-0.05A in the proper-motion object LP 944-20 (which is also known as BRI 0337-3535). This Li detection implies that LP 944-20 is a brown dwarf…

The atmospheres of low-temperature brown dwarfs and gas giant planets are expected to contain the phosphine molecule, PH$_3$ However, previous observations have shown much lower abundances of this molecule than predicted by atmospheric…

The lithium abundance in 62 halo dwarfs is determined from accurate equivalent widths reported in the literature and an improved infrared flux method (IRFM) temperature scale. The Li abundance of 41 plateau stars (those with Teff > 6000 K)…

Theoretical aspects of modeling of spectra of late M- and L-dwarfs are discussed. We show, that the processes of formation of spectra of M- and L-dwarfs are basically different. Instead of the case of M-dwarfs, atoms of Ti and V should be…

We present new observations of the binary Sirius A / Sirius B performed with HST-GHRS. Two interstellar clouds are detected on this sightline, one of them being identified as the Local Interstellar Cloud (LIC). The interstellar structure of…

We present a non-local thermodynamic equilibrium abundance analysis of the resonance doublet Li I at 6707.8 A for 55 Galactic F and G supergiants and bright giants. The derived lithium abundances log \epsilon(Li) may be considered in three…