Search Publications
Search for new variable stars in the northern sky
Tautvaišienė, G.; Drazdauskas, A.; Mikolaitis, Š. +5 more
With the aim to find and characterize new variable stars, we obtained 24 470 CCD images in 13 fields of 0.4 square degrees with a 35/51 cm Maksutov-type semi-robotic telescope at the Molėtai Astronomical Observatory of Vilnius University. From photometric time series of 3604 stars analysed, we found 11 periodic variable stars and 70 slowly varying…
Investigating the OB associations in CMa using eclipsing binary systems: Preliminary results on LV CMa
Bakış, V.; Tunç, E.
In this study, an eclipsing binary of a short orbital period (P = 1.d1834857) LV CMa (V = 8.m7) is selected as a candidate member of an association in the direction of CMa OB1/R1 region. Light curves in UBVRcIc photometric bands were obtained and low-resolution (R ∼ 5500) spectra were collected. Prelimin…
Variability analysis of δ Scuti candidate stars
Tautvaišienė, G.; Drazdauskas, A.; Mikolaitis, Š. +5 more
The Hipparcos catalogue contains stars suspected to be δ Scuti variables for which extensive groundbased observations and characterisation of variability are desired. We obtained 24 215 CCD images with the 35/51 cm Maksutov-type robotic telescope at the Molėtai Astronomical Observatory (MAO, Lithuania) of thirteen δ Scuti candidates selected from …
Long-term spectroscopic survey of T Tauri stars in the Taurus-Auriga star-forming region
Kundra, E.; Budaj, J.; Guenther, E. +5 more
Long-term spectroscopic monitoring of 22 T Tauri stars located in the Taurus-Auriga star-forming region (SFR) is presented. The medium and high-dispersion spectra were obtained at the Stará Lesná (SLO), Skalnaté Pleso (SPO) and Tautenburg observatory (TLS) during 2015—2018. The broadening function technique was used to determine the radial and pro…
Absolute parameters and period variation in a semidetached eclipsing variable V2247 Cyg
Volkov, I. M.; Ikonnikova, N. P.; Burlak, M. A.
We aim to determine the absolute parameters of the components of a poorly studied Algol-type eclipsing binary V2247 Cyg. The data analysis is based on our numerous precise UBVRcIc photometric observations and low resolution spectra. The photometric solution reveals a semi-detached configuration with a less-massive component filling its Roche lobe.…
The nature of light variations in magnetic hot stars
Niemczura, E.; Huang, L.; Krtička, J. +6 more
Magnetic stars show several types of light variability which is modulated by the stellar rotation. In chemically peculiar stars, the redistribution of the flux in the surface regions with peculiar chemical composition leads to the light variability with a typical amplitude of the order of hundredths of magnitude. The most efficient processes that …
Multiple, short-lived "stellar prominences" on the O giant ξ Persei: a magnetic star?
Henrichs, H. F.; Sudnik, N.
We present strong evidence for a rotation period of 2.0406 d of the O giant ξ Persei, derived from the NIV λ1718 wind line in 12 yr of IUE data. We predict that ξ Per has a magnetic dipole field, with superposed variable magnetic prominences. Favorable dates for future magnetic measurements can be predicted. We also analysed time-resolv…
Rotational properties of magnetic chemically peculiar stars
Paunzen, E.; Bernhard, K.; Hümmerich, S. +1 more
The magnetic chemically peculiar (mCP) stars of the upper main sequence exhibit strong and globally organized magnetic fields that are inclined to the rotational axis and facilitate the development of surface abundance inhomogeneities resulting in photometric and spectroscopic variability. Photometric time series data are much easier to obtain tha…
Orbital period changes in RW CrA, DX Vel and V0646 Cen
Chochol, D.; Mašek, M.; Volkov, I. M. +2 more
We aim to determine the absolute parameters of the components of southern Algol-type binaries with deep eclipses RW CrA, DX Vel, V0646 Cen and interpret their orbital period changes. The data analysis is based on a high quality Walraven photoelectric photometry, obtained in the 1960-70s, our recent CCD photometry, ASAS (Pojmanski, 2002), and Hippa…
First results from the use of the relativistic and slim disc model SLIMULX in XSPEC
Castro-Tirado, A. J.; Dovčiak, M.; Karas, V. +3 more
Ultra-Luminous X-ray sources (ULXs) are accreting black holes for which their X-ray properties have been seen to be different to the case of stellar-mass black hole binaries. For most of the cases their intrinsic energy spectra are well described by a cold accretion disc (thermal) plus a curved high-energy emission components. The mass of the blac…