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Title: A LABORATORY log(gf) MEASUREMENT OF THE Ti II 15873.84 Å H-BAND LINE IN SUPPORT OF SDSS-III APOGEE

The SDSS-III APOGEE collaboration has identified a single useable line in the H-band spectra of APOGEE target stars arising from a singly ionized species. This line of Ti II (λ{sub air} = 15873.84 Å) is therefore of great importance for use in stellar surface gravity, or log(g), determinations via the Saha equation. While a theoretical estimate of the line strength exists, to date no laboratory measurement of the line strength has been reported. Herein we report an absolute laboratory transition probability measurement for this important Ti II line. A relative line strength measurement is made of the Ti II H-band line of interest and a reference line with a previously reported absolute transition probability. This ratio is measured using multiple spectra of a high-current water-cooled HC lamp recorded with a calibrated FT-IR spectrometer.
Authors:
;  [1] ;  [2]
  1. Department of Physics, University of Wisconsin-Madison, Madison, WI 53703 (United States)
  2. McDonald Observatory, University of Texas at Austin, Fort Davis, TX 79734 (United States)
Publication Date:
OSTI Identifier:
22365830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 787; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASTROPHYSICS; EMISSION SPECTRA; FOURIER TRANSFORMATION; GRAVITATION; INFRARED SPECTRA; PROBABILITY; SAHA EQUATION; STARS; SURFACES; TITANIUM IONS; WATER CURRENTS