Related papers: HD 69686: A Mysterious High Velocity B Star
The unexpected high bump in the UV part of the spectrum found in nearby giant elliptical galaxies, a.k.a. the UV upturn, has been a subject of debate. A remarkable progress has been made lately from the observational side, mainly involving…
We estimate the distribution of ejection velocities for the known population of high galactic latitude runaway stars. The initial sample is a collection of 174 early-type stars selected from the literature. The stars are first classified…
We present the results of a spectroscopic and photometric analysis of HD314884, a slowly pulsating B star (SPB) in a binary system with detected soft X-ray emission. We spectrally classify the B star as a B5V-B6V star with T$_{eff}$ =…
The young binary system HD 350731 is a noteworthy laboratory for studying early-type binaries with similar components. We present here the analysis of differential multi-color photometric and spectroscopic observations for the double-lined…
Classical Be (CBe) stars are rapidly rotating B-type stars with Balmer emission lines that originated from the decretion disks surrounding them in their spectra. Accounting for $\sim$20% of all B-type stars, most CBe stars are thought to…
The existence of intermediate-mass black holes (IMBHs) is crucial for understanding various astrophysical phenomena, yet their existence remains elusive, except for the LIGO-Virgo detection. We report the discovery of a high-velocity star…
Not all stars exhibiting the optical spectral characteristics of B[e] stars share the same evolutionary stage. The Galactic B[e] star MWC 137 is a prime example of an object with uncertain classification, with previous work suggesting pre-…
It has long been known that the vertical motions of Galactic disk stars increase with stellar age, commonly interpreted as vertical heating through orbit scattering. Here we map the vertical actions of disk stars as a function of age…
Young, massive stars in the Galactic halo are widely supposed to be the result of an ejection event from the Galactic disk forcing some stars to leave their place of birth as so-called runaway stars. Here, we present a detailed…
The blue straggler phenomenon is not yet well explained by current theory; however, evolutionary models of star clusters call for a good knowledge of it. Here we try to understand the possible formation scenario of HD 73666, a blue…
The kinematic parameters identified from high-velocity stars situated within 100 kpc are examined and analyzed. We included three high velocity programs comprising 591, 87, and 519 stars as a function of distances ranging from 0.10 to…
In the 60's, Prof. Stroemgren proposed to use space velocities and ages of moderately young stars to compute their places of formation in order to study the spiral structure in the Galaxy. We have extended this idea to very young stellar…
A significant percentage of OB stars are runaways, so we should expect a similar percentage of their evolved descendants to also be runaways. However, recognizing such stars presents its own set of challenges, as these older, more evolved…
DDO68 (UGC5340) is an unusual dwarf galaxy with extremely low gas metallicity (12+log(O/H) = 7.14) residing in the nearby Lynx-Cancer void. Despite its apparent isolation, it shows both optical and HI morphological evidence for strong tidal…
Recent spectroscopic analysis has set an upper limit to the age of the S-stars, the ~30 B-type stars in highly eccentric orbits around the supermassive black hole (SMBH) in the Galactic center. The inferred age (<15 Myr) is in tension with…
Low-mass, variable, high-velocity stars are interesting study cases for many aspects of Galactic structure and evolution. Until recently, the only known high- or hyper-velocity stars were young stars thought to originate from the Galactic…
We report here on a detailed study of a c-type RR Lyrae variable (RRc variable), SB 796, serendipitously discovered in a search of the WASP public data for stars that display large photometric periodic modulation. SB 796 displays a period…
We present the results of a study of the star HD 34736. The spectropolarimetric observations carried out at the 6-m telescope showed the presence of a strong variable longitudinal magnetic field, exceeding -4500 G. The analysis of the…
A recent discovery of two stellar clusters associated with the diffuse high-latitude cloud HRK 81.4-77.8 has important implications for star formation in the Galactic halo. We derive a plausible distance estimate to HRK 81.4-77.8 primarily…
The spectrum of the evolved B8 III giant HR 62 exhibits weak He-lines and strong Mn and P lines. HR 62 therefore resembles both a HgMn star (CP3) and a He-weak PGa star (CP4). This study is a companion project to a high resolution survey of…