TIC 5724661: A Long-Period Binary with a Pulsating sdB Star and δ Scuti Variable

Jayaraman, Rahul, Rapport, Saul A., Nelson, Lorne, Kurtz, Donald Wayne orcid iconORCID: 0000-0002-1015-3268, Dufresne, George, Handler, Gerald, Senhadji, Abdel, Latham, David W. and Et, Al (2022) TIC 5724661: A Long-Period Binary with a Pulsating sdB Star and δ Scuti Variable. The Astrophysical Journal .

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Official URL: https://doi.org/10.3847/1538-4357/ac84d0


Using the novel TESS 20-sec cadence data, we have discovered an unusual combination of pulsating stars in what we infer to be a binary system. The primary is a standard δ Scuti star with pulsations over the range 32-41 d−1; this is in an inferred wide orbit with a hot subdwarf B (sdB) secondary, which itself has a large-amplitude p-mode pulsation at 524 d−1. We establish constraints on the period of the putative binary by using radial velocity measurements of the δ Scuti star and show that any sdB-mass companion star must have an orbital period greater than ∼35 d. Our identification of this sdB binary serves as an important addition to the relatively small amount of sdB binaries known to have a period longer than a few days. We show that such a binary can be formed through stable, nonconservative mass transfer, without undergoing a common envelope phase.

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