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Ulrich HEBER & collaboration MUCHFUSS

The fastest hot subdwarfs revisited

(Volume 92 - Année 2023 — Numéro 2 - PROCEEDINGS OF THE 10TH MEETING ON HOT SUBDWARFS AND RELATED OBJECTS)
DOI: 10.255118/0037-9565.11205
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Abstract

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 spectral energy distributions using a new grid of tailored model atmospheres and report preliminary results. The sample is dominated by H-rich subdwarfs and their distribution in the Kiel diagram appears to be bimodal for the sdB stars but otherwise fits canonical evolutionary models well. Gaia’s proper motion measurements allowed a precise kinematic investigation to be made. It turns out that all previously proposed HVS candidates are actually bound to the Galaxy, except US 708. The original candidate sample turns out to belong to an extreme halo population. The scarcity of available observations of US 708 calls for space-based UV and IR photometry as well as high precision radial velocity measurements.

1Article publié selon les termes et les conditions de la licence Creative Commons CC-BY 4.0

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Pour citer cet article

Ulrich HEBER & collaboration MUCHFUSS, «The fastest hot subdwarfs revisited», Bulletin de la Société Royale des Sciences de Liège [En ligne], Volume 92 - Année 2023, Numéro 2 - PROCEEDINGS OF THE 10TH MEETING ON HOT SUBDWARFS AND RELATED OBJECTS, 1-9 URL : https://popups.uliege.be/0037-9565/index.php?id=11205.

A propos de : Ulrich HEBER

Dr. Karl Remeis-Sternwarte & ECAP, Astronomical Institute, FAU, University of Erlangen-Nuremberg, Germany, ulrich.heber@fau.de

A propos de : collaboration MUCHFUSS

MUCHFUSS collaboration: see Geier et al. (2015b)