Search Publications
The hierarchical triple nature of the former red nova precursor candidate KIC 9832227
Hartman, Joel D.; Bakos, Gáspár Á.; Kovacs, Geza
We revisit the issue of period variation of the recently claimed red nova precursor candidate KIC 9832227. By using the data gathered during the main mission of the Kepler satellite, and data collected by ground-based wide-field surveys and other monitoring programs (such as ASAS-SN), we find that the currently available timing data strongly suppo…
Surface magnetic activity of the fast-rotating G5 giant IN Comae, central star of the faint planetary nebula LoTr 5
Strassmeier, K. G.; Weber, M.; Ilyin, I. +8 more
Context. On the asymptotic giant branch, low to intermediate mass stars blow away their outer envelopes, forming planetary nebulae. Dynamic interaction between the planetary nebula and its central progenitor is poorly understood. The interaction is even more complex when the central object is a binary star with a magnetically active component, as …
Observability of hydrogen-rich exospheres in Earth-like exoplanets
dos Santos, Leonardo A.; Bourrier, Vincent; Ehrenreich, David +1 more
Context. The existence of an extended neutral hydrogen exosphere around small planets can be used as evidence of the presence of water in their lower atmosphere, but, to date, such a feature has not been securely detected in rocky exoplanets. Planetary exospheres can be observed using transit spectroscopy of the Lyman-α line, which is limited main…
Hot subdwarf wind models with accurate abundances. I. Hydrogen dominated stars HD 49798 and BD+18° 2647
Mereghetti, S.; Pintore, F.; Krtička, J. +5 more
Context. Hot subdwarfs are helium burning objects in late stages of their evolution. These subluminous stars can develop winds driven by light absorption in the lines of heavier elements. The wind strength depends on chemical composition which can significantly vary from star to star.
Aims: We aim to understand the influence of metallicity on…
Detection of nitrogen gas in the β Pictoris circumstellar disc
Snellen, I. A. G.; Lecavelier des Etangs, A.; Bourrier, V. +4 more
Context. The gas composition of the debris disc surrounding β Pictoris is rich in carbon and oxygen relative to solar abundances. Two possible scenarios have been proposed to explain this enrichment. The preferential production scenario suggests that the produced gas may be naturally rich in carbon and oxygen, while the alternative preferential de…
Detailed X-ray spectroscopy of the magnetar 1E 2259+586
Tiengo, A.; Israel, G.; Mereghetti, S. +7 more
Magnetic field geometry is expected to play a fundamental role in magnetar activity. The discovery of a phase-variable absorption feature in the X-ray spectrum of SGR 0418+5729, interpreted as cyclotron resonant scattering, suggests the presence of very strong non-dipolar components in the magnetic fields of magnetars. We performed a deep XMM-Newt…
New powerful outburst of the unusual young star V1318 Cygni S (LkHα 225)
Magakian, T. Yu.; Movsessian, T. A.; Andreasyan, H. R. +1 more
Aims: Young double star V1318 Cyg, which is associated with a small isolated star-forming region around HAeBe star BD+40°4124, has very unusual photometric and spectral behavior. We present results of photometric and spectroscopic observations in the optical range.
Methods: We carried out BVRI CCD photometric observations of V1318 Cyg fr…
Molecular gas content of shell galaxies
Duc, P. -A.; Combes, F.; Mancillas, B.
Shells are fine stellar structures that are identified by their arc-like shapes around a galaxy. They are currently thought to be vestiges of galaxy interactions and/or mergers. The study of their number, geometry, stellar populations, and gas content can help us to derive the interaction or merger history of a galaxy. Numerical simulations have p…
Inversion of HIPPARCOS and Gaia photometric data for asteroids. Asteroid rotational properties from sparse photometric data
Tanga, P.; Cellino, A.; Hestroffer, D. +2 more
Context. Sparse photometric data can be used to determine the spin properties and infer information about the shapes of asteroids. The algorithm adopted for the inversion of Gaia photometric data assumes, for the sake of simplicity and to minimize CPU execution time, that the objects have triaxial ellipsoid shapes. In the past, this algorithm was …
The origin of R CrA variability. A complex triple system hosting a disk
Messina, S.; D'Orazi, V.; Desidera, S. +5 more
Context. R CrA is the brightest member of the Coronet star-forming region and is the closest Herbig AeBe star with a spectrum dominated by emission lines. Its luminosity has been monitored since the end of the nineteenth century, but the origin of its variability, which shows a stable period of 65.767 ± 0.007 days, is still unknown.
Aims: We …