Search Publications
EPIC 206197016: A very hot white dwarf orbited by a strongly irradiated red dwarf
Fossati, L.; Zejda, M.; Paunzen, E. +7 more
Context. Very precise satellite photometry has revealed a large number of variable stars whose variability is caused either by surface spots or by binarity. Detailed studies of such variables provide insights into the physics of these objects.
Aims: We study the nature of the periodic light variability of the white dwarf EPIC 206197016 that w…
Disentangling the nature of the prototype radio weak BL Lac. Contemporaneous multifrequency observations of WISE J141046.00+740511.2
Masetti, N.; Chavushyan, V.; Acosta-Pulido, J. A. +13 more
Context. The γ-ray emitting source WISE J141046.00+740511.2 has been associated with a Fermi-LAT detection by crossmatching with Swift/XRT data. It has shown all the canonical observational characteristics of a BL Lac source, including a power-law, featureless optical spectrum. However, it was only recently detected at radio frequencies and its ra…
Photospheric magnetic flux and coronal emission properties of small-scale bright and faint loops in the quiet Sun
Madjarska, Maria S.; Wiegelmann, Thomas; Galsgaard, Klaus
Context. The study explores the photospheric magnetic properties of bright and faint small-scale loop systems in the solar atmosphere of the quiet Sun, also known as X-ray or coronal bright points.
Aims: To understand how plasma confined in small-scale loops is heated to million degrees, the loop-associated photospheric and coronal magnetic f…
The source of unusual coronal upflows with photospheric abundance in a solar active region
Barczynski, K.; Peter, H.; Zhukov, A. N. +21 more
Context. Upflows in the corona are of importance, as they may contribute to the solar wind. There has been considerable interest in upflows from active regions (ARs). The coronal upflows that are seen at the edges of active regions have coronal elemental composition and can contribute to the slow solar wind. The sources of the upflows have been ch…
First detection of deuterated methylidyne (CD) in the interstellar medium
Wyrowski, Friedrich; Menten, Karl M.; Jacob, Arshia M. +1 more
While the abundance of elemental deuterium is relatively low (D/H ~ a few ×10−5), orders of magnitude higher D/H abundance ratios have been found for many interstellar molecules, enhanced by deuterium fractionation. In cold molecular clouds (T < 20 K), deuterium fractionation is driven by the H2D+ ion, whereas a…
A multiyear photopolarimetric study of the semi-regular variable V CVn and identification of analog sources
Ignace, R.; Simpson, J.; Shrestha, M. +4 more
The semi-regular variable star V Canum Venaticorum (V CVn) is well known for its unusual linear polarization position angle (PA). Decades of observing V CVn reveal a nearly constant PA spanning hundreds of pulsation cycles. This phenomenon has persisted through variability that has varied by two magnitudes in optical brightness and through variabi…
Long-period radial velocity variations of nine M red giants. The detection of substellar companions around HD 6860 and HD 112300
Lee, Byeong-Cheol; Do, Hee-Jin; Park, Myeong-Gu +7 more
Context. Certain periodic variations of radial velocities (RVs) of wobbling giants originate from exoplanets. A number of exoplanets have been discovered around giant stars.
Aims: The purpose of our study is to find low-amplitude and long-period RV variations around bright M (super) giants in the red giant branch (or asymptotic giant branch) …
3D stellar motion in the axisymmetric Galactic potential and the e-z resonances
Barros, Douglas A.; Michtchenko, Tatiana A.
Context. The full phase-space information on the kinematics of a huge number of stars provided by Gaia Data Release 3 increases the demand for a better understanding of the 3D stellar dynamics.
Aims: In this paper, we investigate the possible regimes of motion of stars in the axisymmetric approximation of the Galactic potential, applying a 3D…
New red giants in NGC 6791 and NGC 6819 using Kepler superstamps
Hekker, S.; Covelo-Paz, A.; Themeßl, N. +1 more
Context. Stars that are members of stellar clusters are assumed to be formed at the same time and place from material with the same initial chemical composition. These additional constraints on the ensemble of cluster stars make these stars suitable as benchmarks.
Aims: We aimed (1) to identify previously unknown red giants in the open cluste…
Discovery of an extended G giant chromosphere in the 2019 eclipse of γ Per
Schmitt, J. H. M. M.; Fridlund, M.; Schröder, K. -P. +3 more
The November 2019 eclipse of γ Per was a rare opportunity to seek evidence for a chromosphere of the G8 giant, hitherto suspected but not detected. Twenty-nine years after the only other observed eclipse, we aim to find chromospheric absorption in the strong Ca II H&K lines, and to determine its column densities and scale height. Using the Tel…