Search Publications
A search for runaway stars in 12 Galactic supernova remnants
Mugrauer, Markus; Lux, Oliver; Bischoff, Richard +1 more
Runaway stars can result from core collapse supernovae in multiple stellar systems. If the supernova disrupts the system, the companion is ejected with its former orbital velocity. A clear identification of a runaway star can yield the time and place of the explosion, as well as orbital parameters of the pre supernova binary system. Previous searc…
An investigation of open cluster Melotte 72 using Gaia DR2
Hendy, Yasser; Tadross, Ashraf
The estimation of the main parameters of star clusters is significant in astrophysical studies. The most important aspect of using the Gaia DR2 survey lies in the positions, parallax, and proper motions of cluster stars with homogeneous photometry that make the membership probability determine with high accuracy. In this respect, depending on Gaia…
Jet‑triggered star formation in young radio galaxies
Baum, Stefi; Morganti, Raffaella; Tremblay, Grant +7 more
Emission in the ultraviolet continuum is a salient signature of the hot, massive and consequently short-lived, stellar population that traces recent or ongoing star formation. With the aim of mapping star forming regions and morphologically separating the generic star formation from that associated with the galaxy-scale jet activity, we obtained h…
Astrophysical parameters and dynamical evolution of open clusters: NGC 2587, Collinder 268 and Melotte 72, and Pismis 7
Çakmak, Hikmet; Karataş, Yüksel; Bonatto, Charles +1 more
We determined astrophysical and dynamical parameters of the open clusters (OCs) NGC 2587, Collinder 268 (Col 268), Melotte 72 (Mel 72), and Pismis 7 from Gaia DR2 photometric/astrometric data and a new technique, fitCMD. fitCMD provides (Z, Age(Gyr)) as (0.025, 0.45) for NGC 2587, (0.0025, 0.5) for Col 268, (0.011, 1.25) for Mel 72, and (0.008, 1.…
Kinematics and ellipsoidal motion of the mid to late M-type stars
Elsanhoury, Waleed H.; Al-Johani, Amnah S.; Nouh, Mohamed I. +1 more
Truly, kinematics in the Solar neighborhood has provided important information both for the structure and for the evolution of the Galaxy since the early 20th century. The relationship between Oort constants and the ratio of the velocity dispersion are important quantities in stellar kinematics. In the present paper, we calculated the kinematical …
Fundamental parameters and non local thermodynamic equilibrium abundances of key light elements for nine bright and nearby K giants
Lee, Byeong-Cheol; Han, Inwoo; Lyubimkov, Leonid S. +4 more
For nine bright K giants within 100 pc of the sun, the fundamental parameters and the non local thermodynamic equilibrium (LTE) abundances of three key light elements (Li, C, and O) are accurately determined. These stars are of special interest due to the planets detected around them. Their fundamental parameters are found to be typical for K gian…
Critical comments on publications by S. Hoffmann and N. Vogt on historical novae/supernovae and their candidates
Neuhäuser, Ralph; Neuhäuser, Dagmar L.
We critically discuss recent articles by S. Hoffmann and N. Vogt on historical novae and supernovae (SNe) as well as their list of "24 most promising events" "with rather high probability to be a nova" (Hoffmann et al., AN, 2020, 341, 79 (P3)). Their alleged positional accuracy of previously suggested historical nova/SN records is based on inhomog…
A small radio galaxy at z = 4.026
Paragi, Zsolt; Krezinger, Máté; Frey, Sándor +8 more
Less than $200$ radio-loud active galactic nuclei (AGN) are known above redshift $4$. Around $40$ of them have been observed at milliarcsecond (mas) scale resolution with very long baseline interferometry (VLBI) technique. Some of them are unresolved, compact, relativistically beamed objects, blazars with jets pointing at small angles to the obser…
Identification of additional young nearby runaway stars based on Gaia data release 2 observations and the lithium test
Torres, Guillermo; Mugrauer, Markus; Michel, Kai-Uwe +4 more
Runaway stars are characterized by their remarkably high space velocities, and the study of their formation mechanisms has attracted considerable interest. Young, nearby runaway stars are the most favorable for identifying their place of origin, and for searching for possible associated objects such as neutron stars. Usually, the research field of…
1H 0707-495: An AGN is dimming its X-ray light
Boller, Thomas
We report on one of the first science observations obtained during the Calibration and Verification phase of extended ROentgen Survey with an Imaging Telescope Array (eROSITA) aboard the Spectrum-Roentgen-Gamma (SRG) mission on the famous Narrow-Line Seyfert 1 Galaxy 1H 0707-495. 1H 0707-495 is a highly variable AGN, with a complex, steep X-ray sp…