205 citations · 1.4k across the 44 of their papers we have counts for
45 papers
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…
Columbae: the recently stripped, pulsating core of a massive star
Andreas Irrgang, Norbert Przybilla, Georges Meynet
A vital condition for life on Earth is the steady supply of radiative heat by the Sun. Like all other stars, the Sun generates its emitted energy in its central regions where densi…
Sub-stellar Companions of Intermediate-mass Stars with CoRoT: CoRoT-34b, CoRoT-35b, and CoRoT-36b
D. Sebastian, E. W. Guenther, M. Deleuil +17
Theories of planet formation give contradicting results of how frequent close-in giant planets of intermediate mass stars (IMSs; ) are…
The OmegaWhite Survey for Short-Period Variable Stars VII: High amplitude, short period blue variables
G. Ramsay, P. A. Woudt, T. Kupfer +11
Blue Large Amplitude Pulsators (BLAPs) are a relatively new class of blue variable stars showing periodic variations in their light curves with periods shorter than a few tens of m…
The origin of early-type runaway stars from open clusters
Aakash Bhat, Andreas Irrgang, Ulrich Heber
Runaway stars are ejected from their place of birth in the Galactic disk, with some young B-type runaways found several tens of kiloparsecs from the plane traveling at speeds beyon…
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…
EC 22536-5304: a lead-rich and metal-poor long-period binary
M. Dorsch, C. S. Jeffery, A. Irrgang +2
Helium-burning hot subdwarf stars of spectral types O and B (sdO/B) are thought to be produced through various types of binary interaction. The helium-rich hot subdwarf star EC2253…
A hot subdwarf-white dwarf super-Chandrasekhar candidate supernova Ia progenitor
Ingrid Pelisoli, P. Neunteufel, S. Geier +8
Supernova Ia are bright explosive events that can be used to estimate cosmological distances, allowing us to study the expansion of the Universe. They are understood to result from…
Space observations of AA Doradus provide consistent mass determinations. New HW-Vir systems observed with TESS
A. S. Baran, R. H. Østensen, U. Heber +5
We present an overview of eclipsing systems of the HW-Virginis type, based on space observations from the TESS Mission. We perform a detailed analysis of the properties of AA Dor,…
Hubble spectroscopy of LB-1: comparison with B+black-hole and Be+stripped-star models
D. J. Lennon, J. Maíz Apellániz, A. Irrgang +10
LB-1 has variously been proposed as either an X-ray dim B-type star plus black hole (B+BH) binary, or a Be star plus an inflated stripped star (Be+Bstr) binary. The Space Telescope…
Blue extreme disk-runaway stars with Gaia EDR3
Andreas Irrgang, Markus Dimpel, Ulrich Heber +1
Since the discovery of hypervelocity stars in 2005, it has been widely believed that only the disruption of a binary system by a supermassive black hole at the Galactic center (GC)…
A quantitative in-depth analysis of the prototype sdB+BD system SDSS J08205+0008 revisited in the Gaia era
V. Schaffenroth, S. L. Casewell, D. Schneider +8
Subdwarf B stars are core-helium burning stars located on the extreme horizontal branch. Extensive mass loss on the red giant branch is necessary to form them. It has been proposed…
Runaway blue main-sequence stars at high Galactic latitudes. Target selection with Gaia and spectroscopic identification
Roberto Raddi, Andreas Irrgang, Ulrich Heber +2
Motivated by the historical identification of runaway main-sequence (MS) stars of early spectral type at high Galactic latitudes, we test the capability of Gaia at identifying new…
EPIC 216747137: a new HW Vir eclipsing binary with a massive sdOB primary and a low-mass M-dwarf companion
R. Silvotti, V. Schaffenroth, U. Heber +8
EPIC 216747137 is a new HW~Virginis system discovered by the Kepler spacecraft during its K2 "second life". Like the other HW Vir systems, EPIC 216747137 is a post-common-envelope…
Heavy-metal enrichment of intermediate He-sdOB stars: the pulsators Feige 46 and LS IV -14 116 revisited
M. Dorsch, M. Latour, U. Heber +3
Hot subdwarf stars of types O and B represent a poorly understood phase in the evolution of low-mass stars. Many subdwarfs show rich oscillations and are among the most chemically…
A new class of Roche lobe-filling hot subdwarf binaries
Thomas Kupfer, Evan B. Bauer, Kevin B. Burdge +30
We present the discovery of the second binary with a Roche lobe-filling hot subdwarf transferring mass to a white dwarf (WD) companion. This 56 minute binary was discovered using d…
A proto-helium white dwarf stripped by a substellar companion via common-envelope ejection -- Uncovering the true nature of a candidate hypervelocity B-type star
Andreas Irrgang, Stephan Geier, Ulrich Heber +3
In the past, SDSS J160429.12+100002.2 was spectroscopically classified as a blue horizontal branch (BHB) star. Assuming a luminosity that is characteristic of BHB stars, the object…
Mode identification in three pulsating hot subdwarfs observed with TESS satellite
S. K. Sahoo, A. S. Baran, U. Heber +12
We report on the detection of pulsations of three pulsating subdwarf B stars observed by the TESS satellite and our results of mode identification in these stars based on an asympt…
A stripped helium star in the potential black hole binary LB-1
Andreas Irrgang, Stephan Geier, Simon Kreuzer +2
The recently claimed discovery of a massive () black hole in the Galactic solar neighborhood has led to controversial discussions because it…
PG 1610062: a runaway B star challenging classical ejection mechanisms
Andreas Irrgang, Stephan Geier, Ulrich Heber +2
Hypervelocity stars are rare objects, mostly main-sequence (MS) B stars, traveling so fast that they will eventually escape from the Milky Way. Recently, it has been shown that the…
Asteroseismology of massive stars with the TESS mission: the runaway Beta Cep pulsator PHL 346 = HN Aqr
Gerald Handler, Andrzej Pigulski, Jadwiga Daszyńska-Daszkiewicz +21
We report an analysis of the first known Beta Cep pulsator observed by the TESS mission, the runaway star PHL 346 = HN Aqr. The star, previously known as a singly-periodic pulsator…
A quantitative NLTE analysis of visual and ultraviolet spectra of four helium-rich subdwarf O stars
Markus Schindewolf, Peter Nemeth, Ulrich Heber +4
Hot subdwarfs represent a poorly understood late phase of stellar evolution. While binary evolution plays an important role for B-subdwarfs (sdB), the origin of the He dominated O-…
Hypervelocity stars in the Gaia era: Runaway B stars beyond the velocity limit of classical ejection mechanisms
Andreas Irrgang, Simon Kreuzer, Ulrich Heber
Young massive stars in the halo are assumed to be runaway stars from the Galactic disk. Possible ejection scenarios are binary supernova ejections (BSE) or dynamical ejections from…
A quantitative spectral analysis of 14 hypervelocity stars from the MMT survey
Andreas Irrgang, Simon Kreuzer, Ulrich Heber +1
Hypervelocity stars (HVSs) travel so fast that they may leave the Galaxy. The tidal disruption of a binary system by the supermassive black hole in the Galactic center is widely as…