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A spectroscopic and kinematic survey of fast hot subdwarfs
S. Geier, U. Heber, A. Irrgang +19
Hot subdwarfs (sdO/B) are the stripped helium cores of red giants formed by binary interactions. Close hot subdwarf binaries with massive white dwarf companions have been proposed…
A 500 pc volume-limited sample of hot subluminous stars I. Space density, scale height, and population properties
H. Dawson, S. Geier, U. Heber +25
We present the first volume-limited sample of spectroscopically confirmed hot subluminous stars out to 500 pc, defined using the accurate parallax measurements from the {\em Gaia}…
The photospheres of the hottest fastest stars in the Galaxy
Klaus Werner, Nicole Reindl, Thomas Rauch +2
We perform nonlocal thermodynamic equilibrium (NLTE) model atmosphere analyses of the three hottest hypervelocity stars (space velocities between 1500-2800 km s) k…
The unusual planetary nebula nucleus in the Galactic open cluster M37 and six further hot white dwarf candidates
Klaus Werner, Nicole Reindl, Roberto Raddi +6
Planetary nebulae in Galactic open star clusters are rare objects; only three are known to date. They are of particular interest because their distance can be determined with high…
The bright blue side of the night sky: Spectroscopic survey of bright and hot (pre-) white dwarfs
Nicole Reindl, Ramazan Islami, Klaus Werner +10
We report on the spectroscopic confirmation of 68 new bright ( mag) and blue (pre-)white dwarfs (WDs). This finding has allowed us to almost double the number of the h…
Post-red-giant-branch Planetary Nebulae
David Jones, Todd Hillwig, Nicole Reindl
Common envelope events have been associated with the formation of a planetary nebulae since its proposition more than forty five years ago. However, until recently there have been…
The binary and the disk: the beauty is found within NGC3132 with JWST
Raghvendra Sahai, Valentin Bujarrabal, Guillermo Quintana-Lacaci +4
The planetary nebula (PN) NGC3132 is a striking example of the dramatic but poorly understood, mass-loss phenomena that (1-8) Msun stars undergo during their death throes as they e…
Astro-photometric study of M37 with Gaia and wide-field ugi-imaging
M. Griggio, L. R. Bedin, R. Raddi +15
We present an astrometric and photometric wide-field study of the Galactic open star cluster M37 (NGC 2099). The studied field was observed with ground-based images covering a regi…
Pulsating hydrogen-deficient white dwarfs and pre-white dwarfs observed with TESS -- IV. Discovery of two new GW Vir stars: TIC0403800675 and TIC1989122424
Murat Uzundag, Alejandro H. Corsico, S. O. Kepler +4
We present two new GW Vir-type pulsating white dwarf stars, TIC\,0403800675 (WD\,J115727.68-280349.64) and TIC\,1989122424 (WD J211738.38-552801.18) discovered in the Transiting Ex…
The population of hot subdwarf stars studied with Gaia -- IV. Catalogues of hot subluminous stars based on Gaia EDR3
Richard Culpan, Stephan Geier, Ingrid Pelisoli +3
In light of substantial new discoveries of hot subdwarfs by ongoing spectroscopic surveys and the availability of the Gaia mission Early Data Release 3 (EDR3), we compiled new rele…
Radial velocity variability and evolution of hot subdwarf stars
S. Geier, M. Dorsch, I. Pelisoli +3
Hot subdwarf stars represent a late and peculiar stage in the evolution of low-mass stars, because they are likely formed by close binary interactions. Here we performed a radial v…
Discovery of hot subdwarfs with extremely high carbon and oxygen abundances
Klaus Werner, Nicole Reindl, Stephan Geier +1
Helium rich subdwarf O stars (sdOs) are hot compact stars in a pre-white dwarf evolutionary state. Most of them have effective temperatures and surface gravities in the range Teff…
Discovery of a highly magnetic He-sdO star from a double-degenerate binary merger
M. Dorsch, N. Reindl, I. Pelisoli +4
Helium-rich hot subdwarf stars of spectral type O (He-sdO) are considered prime candidates for stellar merger remnants. Such events should lead to the generation of strong magnetic…
The post-common-envelope binary central star of the planetary nebula Ou 5: a doubly-eclipsing post-red-giant-branch system
David Jones, James Munday, Romano Corradi +10
We present a detailed study of the stellar and orbital parameters of the post-common envelope binary central star of the planetary nebula Ou~5. Low-resolution spectra obtained duri…
Non-local thermodynamic equilibrium spectral analysis of five hot, hydrogen-deficient pre-white dwarfs
Klaus Werner, Nicole Reindl, Matti Dorsch +3
Hot, compact, hydrogen-deficient pre-white dwarfs (pre-WDs) with effective temperatures of Teff > 70,000 K and a surface gravity of 5.0 < log g < 7.0 are rather rare objects despit…
Pulsating hydrogen-deficient white dwarfs and pre-white dwarfs observed with TESS II. Discovery of two new GW Vir stars: TIC333432673 and TIC095332541
Murat Uzundag, Alejandro H. Córsico, S. O. Kepler +8
In this paper, we present the observations of two new GW Vir stars from the extended \textit{TESS} mission in both 120\,s short-cadence and 20\,s ultra-short-cadence mode of two pr…
White dwarf and subdwarf stars in the Sloan Digital Sky Survey Data Release 16
S. O. Kepler, Detlev Koester, Ingrid Pelisoli +2
White dwarfs are the end state of the evolution of more than 97% of all stars, and therefore carry information on the structure and evolution of the Galaxy through their luminosity…
Asteroseismic cartography of hydrogen-deficient white dwarfs
N. Giammichele, S. Charpinet, G. Fontaine +4
We present the results of the asteroseismic analysis of the hydrogen-deficient white dwarf PG 0112+104 from the -2 field. Our seismic procedure using the forward method bas…
Mysterious, Variable, and Extremely Hot: White Dwarfs Showing Ultra-High Excitation Lines I. Photometric Variability
Nicole Reindl, Veronika Schaffenroth, Semih Filiz +3
About 10% of all stars exhibit absorption lines of ultra-high excited (UHE) metals (e.g. OVIII) in their optical spectra when entering the white dwarf cooling sequence. The recent…
An extremely hot white dwarf with a rapidly rotating K-type subgiant companion: UCAC2 46706450
Klaus Werner, Nicole Reindl, Lisa Löbling +5
UCAC2 46706450 is a late-type star with an ultraviolet (UV) excess. It was considered a candidate to establish a sample of FGK stars with white dwarf (WD) companions that can be us…
Measuring the fine structure constant on a white dwarf surface; a detailed analysis of Fe V absorption in G191-B2B
J. Hu, J. K. Webb, T. R. Ayres +12
The gravitational potential phi = GM/Rc^2 at the surface of the white dwarf G191-B2B is 10,000 times stronger than that at the Earth's surface. Numerous photospheric absorption fea…
An in-depth reanalysis of the alleged type Ia supernova progenitor Henize 2-428
N. Reindl, V. Schaffenroth, M. M. Miller Bertolami +5
The nucleus of the planetary nebula Hen2-428 is a short orbital-period (4.2h), double-lined spectroscopic binary, whose status as a potential supernova type Ia progenitor has raise…
A far-UV survey of three hot, metal-polluted white dwarf stars: WD0455-282, WD0621-376, and WD2211-495
S. P. Preval, M. A. Barstow, M. Bainbridge +7
Using newly obtained high-resolution data () from the \textit{Hubble Space Telescope}, and archival UV data from the \textit{Far Ultraviolet Spectroscopic E…
White dwarf and subdwarf stars in the Sloan Digital Sky Survey Data Release 14
S. O. Kepler, Ingrid Pelisoli, Detlev Koester +6
White dwarfs carry information on the structure and evolution of the Galaxy, especially through their luminosity function and initial-to-final mass relation. Very cool white dwarfs…