Search Publications
The 6.7 keV thermal emission lines in the stellar flare spectra of two chromospherically active Binaries: Algol and GT Mus
Eze, Ambrose Chukwudi; Esaenwi, Sudum; Madu, Fidelis Okey
Chromospherically active binaries' (CABs) are late-type evolved stars with strong chromosphere/coronae and high flare activity levels. Starspot evolution in these CABs and binaries reveals strong stellar and chromospheric activities. In binaries, the tidal interaction via the internal dynamo motion, during rapid rotation of the component stars gen…
A TESS search for donor-star pulsations in high-mass X-ray binaries
Ramsay, Gavin; Hakala, Pasi; Charles, Philip A.
Ground-based optical photometry of the counterparts of high-mass X-ray binaries (HMXBs) has revealed the presence of periodic modulations on time-scales of ~0.3-0.5 d. More recent space-based observations (CoRoT and TESS) of OB and Be stars have shown that pulsations caused by p and g modes are common in early-type stars. We have therefore underta…
Magnetic field measurements of sharp-lined Ap stars
Ilyin, I.; Hubrig, S.; Schöller, M. +2 more
Previous observations suggested that Ap and Bp stars exhibit a bimodal distribution of surface magnetic field strengths and that actually only few or no stars exist with magnetic dipole field strengths below 300 G down to a few Gauss. As the number of Ap and Bp stars currently known to possess weak magnetic fields is not large, it is necessary to …
Mass assembly and active galactic nucleus activity at z ≳ 1.5 in the dense environment of XDCP J0044.0-2033
Tozzi, P.; Merlin, E.; Bongiorno, A. +4 more
Context. XDCP J0044.0−2033 is the most massive galaxy cluster known at z > 1.5 and its core shows a high density of galaxies, which are experiencing mergers and hosting nuclear activity.
Aims: We present a multi-wavelength study of a region of 24 kpc × 24 kpc located ∼157 kpc from the center of the cluster, for which we have photometric an…
Near-infrared detection of H2 flows in the core of the Mon R1 association
Movsessian, T. A.; Andreasyan, H. R.; Tatarnikov, A. M. +1 more
We report the discovery of four new H2 jets in the Mon R1 star-forming region in images obtained with the 2.5-m telescope of the Caucasian Mountain Observatory of Sternberg Astronomical Institute (SAI), Moscow State University (MSU) through a filter centred on the H2 1-0 S(1) emission line. This discovery confirms the nature …
Extending the energy range of AstroSat-CZTI up to 380 keV with compton spectroscopy
Rao, A. R.; Bhalerao, Varun; Mithun, N. P. S. +4 more
The CZTI (Cadmium Zinc Telluride Imager) onboard AstroSat is a high energy coded mask imager and spectrometer in the energy range of 20-100 keV. Above 100 keV, the dominance of Compton scattering cross-section in CZTI results in a significant number of 2-pixel Compton events and these have been successfully utilized for polarization analysis of Cr…
Yet another star in the Albireo system. The discovery of Albireo Ad
Bastian, U.; Schröder, K. -P.; Mittag, M. +1 more
Context. Albireo is a well-known bright visual double star. It is still unclear if the components A and B form a gravitationally bound system. The component Albireo A is itself a binary star. The orbital parameters of the Albireo Aa, Ac system have been determined only recently. Thus, Albireo is still of interest for current research.
Aims: W…
Distance Determination of RR Lyrae Stars AE Leo, AT Vir, and HY Com
Soper, C.; Tenenbaum, C.; Lounsbery, A. +2 more
We present the results of our observations and analyses of three RR Lyrae variable stars: AT Vir, HY Com, and AE Leo, in order to test period-luminosity relationships derived from stellar models. We have measured the periods of these stars to be 0.52359, 0.44898, and 0.63021 days, respectively, closely matching previous work. Period-Luminosity-Met…
BViz Photometry of the RR Lyrae Star RU Ceti
Fickle, J.; Allen, M. L.
The RR Lyrae star RU Cet was observed between October 26 and November 23, 2020. The observations were taken in the B, V, ip, and zs filters, with the telescope images being analyzed using various aperture photometry methods. The period of variation for RU Cet was found to be 0.585 ± 0.020 day. Theoretical period-luminosity-metallicity relations in…
The MOSDEF survey: a new view of a remarkable z = 1.89 merger
Siana, Brian; Shapley, Alice E.; Reddy, Naveen A. +13 more
We present a detailed study of a galaxy merger taking place at z = 1.89 in the GOODS-S field. Here, we analyse Keck/MOSFIRE spectroscopic observations from the MOSFIRE Deep Evolution Field (MOSDEF) survey along with multiwavelength photometry assembled by the 3D-HST survey. The combined data set is modelled to infer the past star formation histori…