Radial velocity measurements of the pulsating zirconium star: LS IV -14 116

Abstract

The helium-rich hot subdwarf LS IV -14 116 shows remarkably high surface abundances of zirconium, yttrium, strontium, and germanium, indicative of strong chemical stratification in the photosphere. It also shows photometric behaviour indicative of non-radial g-mode pulsations, despite having surface properties inconsistent with any known pulsational instability zone. We have conducted a search for radial velocity variability. This has demonstrated that at least one photometric period is observable in several absorption lines as a radial velocity variation with a semi-amplitude in excess of 5 km s${}^{-1}$. A correlation between line strength and pulsation amplitude provides evidence that the photosphere pulsates differentially. The ratio of light to velocity amplitude is too small to permit the largest amplitude oscillation to be radial.

To appear in MNRAS: Accepted 2014 October 20, 6 pages, 2 table, 8 figures

References in corpus (2)

• Discovery of extremely lead-rich subdwarfs: does heavy metal signal the formation of subdwarf B stars?
• Fe-bump instability: the excitation of pulsations in subdwarf B and other low-mass stars

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• Discovery of a second pulsating intermediate helium-enriched sdOB star
• The distribution, kinematics and luminosities of extreme helium stars as probes of their origin and evolution
• Discovery and analysis of three magnetic hot subdwarf stars: evidence for merger-induced magnetic fields