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The fastest hot subdwarfs revisited

Heber, U.; Muchfuss

Hyper-velocity stars (HVS) are enigmatic objects because they are travelling so fast that they escape from the Galaxy. Among hot subdwarfs, only one such star is known, the He-sdO US 708. The Hyper-MUCHFUSS collaboration provided additional HVS candidates. Here we revisit the fastest candidates including US 708 by analysing optical spectra and spe…

The sdBV+dM close-to-synchronization binary TIC 137608661: inclination and thin disk population

Silvotti, Roberto

TIC 137608661 is a new sdBV+dM reflection-effect binary discovered by the TESS space mission with an orbital period of 7.21 hours. In addition to the detailed study of this system that was recently published (Silvotti et al., 2022), this article contains a further discussion on its inclination. Moreover, from the 3D space velocities of the binary …

Kepler, K2, and TESS observations: ensemble and comparative asteroseismology

Reed, M. D.; Jeffery, C. S.; Baran, A. S. +2 more

The original Kepler mission detected 18 pulsating subdwarf B (sdBV) stars, K2 observed 161 of our proposed targets with 41 sdB stars found to show p- or g-mode pulsations, and TESS has observed about 1,000 of our proposed targets. All these data should provide ∼300 sdBV stars, from which asteroseismology will provide a host of measurables. Combine…

New Hot Subdwarf Variables from Gaia eDR3

Kupfer, Thomas; Kosakowski, Alekzander; Barlow, Brad N. +1 more

We present a search for new variable hot subdwarfs from Gaia eDR3 using the Zwicky Transient Facility DR9 and the 2.1 m Otto Struve Telescope at McDonald Observatory. We report the discovery of 22 HW Vir binaries, 24 reflection effect binaries, and 14 ellipsoidally modulated systems. Candidate selection for our high-speed observations was based on…

The origin of subdwarf B stars

Aubrey, Callum; Napiwotzki, Ralf

The origin of subdwarf B stars (sdBs) is unclear. Different formation channels are proposed including: close-binary evolution, helium-mixing on the red giant branch and the hot flasher scenario. Circumstantial evidence exists that sdBs can result from single star evolution in high metallicity populations. We investigate this possibility by using m…