Departures from LTE for neutral Li in late-type stars

By K. Lind, Martin Asplund, Paul Barklem. 2009

221 citations recorded by the source corpus.

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 th e negative hydrogen ion. Non-LTE abundance corrections for the lithium resonance line at 670.7 nm and the subordinate line at 610.3 nm, are calculated using 1D MARCS model atmospheres spanning a grid Teff = [4000, 8000] K, log g = [1.0, 5.0], and [Fe/H] = [0.0,−3.0], for lithium abundances in the range A(Li) = [−0.3, 4.2]. The competing effects of ultraviolet over-ionization and photon losses in th e resonance line govern the behaviour of the non-LTE effects with stellar parameters and lithium abundance. The size and sign of the non-LTE abundance corrections vary signific antly over the grid for the 670.7 nm line, but are typically positive and below 0.15 dex for the 610.3 nm, line. The new collisional data play a significant role in determining the abundance corrections.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/c412a83bd94dc02c28d6b84ac2720d4e7d6d04d2

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In Astronomy and Astrophysics

1. Timothy C. Beers
2. A. Frebel
3. Martin Asplund
4. J. Norris
5. C. Sneden
6. N. Christlieb
7. Paul Barklem
8. S. Ryan

In Instrumentation

1. A. Frebel
2. Timothy C. Beers
3. C. Sneden
4. J. Norris
5. Martin Asplund
6. N. Christlieb
7. I. Thompson
8. S. Shectman

Citations in the corpus

• The GALAH Survey: Second Data Release (2018, methodology): “For DR2 We incorporate non-LTE line formation for several key elements, including Li (Lind et al. 2009), O (Amarsi et al. 2016a), Na (Lind et al. 2011), Mg (Osorio et al. 2015), Al (Nordlander & Lind 2017), Si (Amarsi & Asplund 2017), and Fe (Amarsi et al. 2016b), mostly with additional dedicated…”
• THE MOST METAL-POOR STARS. II. CHEMICAL ABUNDANCES OF 190 METAL-POOR STARS INCLUDING 10 NEW STARS WITH [Fe/H] ⩽ −3.5,, (2012, background): “At present, the observational tests have been limited to the moderately metal-poor globular clusters NGC 6397 (Korn et al. 2007; Lind et al. 2008, 2009b) and NGC 6752 (Korn 2010).”
• Lithium depletion in solar-like stars: no planet connection (2010, methodology): “The non-LTE modeling procedure is the same as described in Lind et al. (2009), but extended to cover also super-solar metallicities.”
• A SEARCH FOR STARS OF VERY LOW METAL ABUNDANCE. VI. DETAILED ABUNDANCES OF 313 METAL-POOR STARS (2014, methodology): “For the Li i 6707 Å line, we use the corrections computed by Lind et al. (2009).”
• Signatures of intrinsic Li depletion and Li-Na anti-correlation in the metal-poor globular cluster NGC 6397 , (2009, methodology): “Non-LTE abundance corrections for Li were calculated according to Lind et al. (2009), a study that is based on calculations on the same MARCS model atmospheres as here (Gustafsson et al. 2008).”
• Non-LTE calculations for neutral Na in late-type stars using improved atomic data (2011, background): “The situation is different from that of Li, for which charge exchange reactions always lead to more neutralisation throughout the atmosphere, with significant line strengthening as a result (Barklem et al. 2003; Lind et al. 2009).”