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M dwarfs found in the first Byurakan spectral sky survey database. Gaia EDR3 and TESS data. Some preliminary results
Gigoyan, K. K.; Gigoyan, K. S.; Kostandyan, G. R. +5 more
In order to gain more information on the 236 M dwarfs identified in the First Byurakan Survey (FBS) low-resolution (lr) spectroscopic database, Gaia EDR3 high-accuracy astrometric and photometric data and Transiting Exoplanet Survey Satellite (TESS) data are used to characterise these M dwarfs and their possible multiplicity. Among the sample of 2…
A Search for Low-amplitude Periodic Brightness Variations in HD 168 443
Bondar', N. I.; Shlyapnikov, A. A.
The paper presents the results of studying light curves of the star HD 168443 obtained from the ground-based and space photometric observations within the ASAS, KWS surveys, and the Hipparcos mission from 1990 to 2020. During 30 years of observations, the average annual brightness of the star remained constant within the measurement errors, the me…
The Li-age relation: Calibration with open clusters and associations
Gilmore, G.; Montes, D.; Randich, S. +6 more
In this work we used a series of open clusters and associations observed by the Gaia-ESO Survey (GES) to study the use of lithium abundances (Li I spectral line at 6708 $\angstrom$) as an age indicator for pre- and main-sequence FGKM late-type stars. Previous studies of open clusters have shown that lithium depletion is not only strongly age depen…
BV photometric observations of the flickering of the dwarf nova RX And
Stoyanov, K. A.; Ivanov, V. D.; Minev, M. +3 more
We report photometry of the intranight variability of the dwarf nova RX~And in two bands ($B$ and $V$). The observations are carried out during three nights in November-December 2022 with the 50/70~cm Schmidt telescope of the Rozhen National Astronomical Observatory. The observations indicate that the amplitude of the flickering is about 0.5 mag i…
Apsidal motion and absolute parameters of GV Nor and V881 Sco based on mid-resolution spectroscopy and TESS photometry
Erdem, Ahmet; Sürgit, Derya; Engelbrecht, Chris A. +5 more
The veracity of stellar evolution models and theoretical internal structure constants may be subjected to stringent tests by using physical parameters obtained from spectroscopic and photometric observations of eclipsing binary systems that exhibit apsidal motion. Two eclipsing binary stars from the southern hemisphere with no prior published spec…
Drop in the Hard Pulsed Fraction and a Candidate Cyclotron Line in IGR J16320-4751 Seen by NuSTAR
Rahoui, F.; Tomsick, J. A.; Rodriguez, J. +10 more
We report on a timing and spectral analysis of a 50 ks NuSTAR observation of IGR J16320-4751 (= AX J1631.9-4752), a high-mass X-ray binary hosting a slowly rotating neutron star. In this observation from 2015, the spin period was 1308.8 ± 0.4 s giving a period derivative $\dot{P}\sim 2\times {10}^{-8}$ s s-1 when compared with the perio…
The origin of subdwarf B stars
Aubrey, Callum; Napiwotzki, Ralf
The origin of subdwarf B stars (sdBs) is unclear. Different formation channels are proposed including: close-binary evolution, helium-mixing on the red giant branch and the hot flasher scenario. Circumstantial evidence exists that sdBs can result from single star evolution in high metallicity populations. We investigate this possibility by using m…
A redshifted excess in the broad emission lines after the flare of the γ-ray narrow-line Seyfert 1 PKS 2004−447
Wolf, C.; Marziani, P.; Berton, M. +6 more
PKS 2004−447 is a narrow-line Seyfert 1 (NLS1) harbouring a relativistic jet with γ-ray emission. On 2019 October 25, the Fermi-Large Area Telescope captured a γ-ray flare from this source, offering a chance to study the broad-line region (BLR) and jet during such violent events. This can provide insights into the BLR structure and jet interaction…
Insight into the Origin of Cometary Ices from Rosetta/ROSINA Mass Spectrometer Data
Rubin, Martin
Here we review some of the major findings of the mass spectrometer suite ROSINA on board of ESA's Rosetta spacecraft to comet 67P/Churyumov-Gerasimenko. For more than 2 years, ROSINA continuously measured the composition of the gases sublimating from the comet's nucleus. ROSINA measurements provided insight into the origin of the ices in 67P/Chury…
X-Rays Trace the Volatile Content of Interstellar Objects
Wang, Q. Daniel; Cabot, Samuel H. C.; Seligman, Darryl Z.
The nondetection of a coma surrounding 1I/'Oumuamua, the first discovered interstellar object (ISO), has prompted a variety of hypotheses to explain its nongravitational acceleration. Given that forthcoming surveys are poised to identify analogs of this enigmatic object, it is prudent to devise alternative approaches to characterization. In this s…