Search Publications
Analysis of photometric and spectroscopic variability of red supergiant Betelgeuse
Jadlovský, Daniel; Krtička, Jiří; Paunzen, Ernst +1 more
Betelgeuse is a pulsating red supergiant whose brightness is semi periodically variable and in February 2020 reached a historical minimum, the Great Dimming. The aims of this study are to characterize Betelgeuse's variability based on available archival data and to study possible causes of light variability. Many spectra, from ultraviolet and opti…
A constrained cosmological model in f(R ,Lm) gravity
Singh, J. K.; Shaily; Myrzakulov, Ratbay +1 more
In this article, we study the expanding nature of the universe in the context of f(R ,Lm) gravity theory, here R represents the Ricci scalar and Lm is the matter Lagrangian density. With a specific form of f(R ,Lm) , we obtain the field equations for flat FLRW metric. We parametrize the deceleration parameter in te…
DeGaPe 35: Amateur discovery of a new southern symbiotic star
Charbonnel, Stéphane; Garde, Olivier; Merc, Jaroslav +6 more
In this work, we present the discovery and characterization of a new southern S-type symbiotic star, DeGaPe 35. We have obtained the low-resolution spectroscopic observations and supplemented them with the photometry from Gaia DR3 and other surveys. The optical spectra of this target show prominent emission lines, including highly ionized [Fe VII]…
Spectroscopic and photometric study of the pulsating eclipsing binary HIP 28271
Chen, Tao; Wang, Kun; Cao, Xingmei
We report the results of the detailed study of the single-lined eclipsing binary HIP 28271 with time-series high-resolution spectra and high-precision TESS photometry. The binary modeling indicates that HIP 28271 has a short orbital period of 2.7404254-4e-7+9e-7 days, with an eccentricity ofeorb = 0.0062-0.001…
New photometric solutions of contact binaries HX UMa and FP Boo
Yıldırım, M. F.
By using different databases (TESS, SuperWASP, KWS and ASAS-SN), light curve analyzes of HX UMa and FP Boo systems were performed, and the changes in the orbital period of the systems were also examined. The light curve analyzes of the systems were conducted simultaneously with the radial velocities using the Wilson and Devinney (WD) code. As a re…
Revisiting the orbital motion of WR 138
Nazé, Yaël; Gosset, Eric; Rauw, Gregor
The optical spectrum of WR 138 exhibits emission lines typical of a WN6o star and absorption lines from a rapidly-rotating OB star. Using a large set of spectroscopic data, we establish a new orbital solution of the WN6o star based on the radial velocities of highly-ionized nitrogen lines. We show that the WN6o star moves on a 4.3 yr orbit with a …
HD 32239: An Algol type eclipsing binary with a γ Doradus type component
Gürol, Birol
HD 32239 is an Algol-type eclipsing binary with one of the components showing γ Doradus type pulsation. In this study by using the Transiting Exoplanet Survey Satellite (TESS) observations of the HD 32239 system published in Sectors 5 and 32, we obtained the minima times of the eclipsing system and calculated the new light elements by using the (O…
OT UMa and 2MASS J09251388+6424488: Two active contact eclipsing binary systems
Dong, A. -J.; Zhang, B.; Mei, K. -Y. +2 more
In this paper, new photometric light curves (LCs) of OT UMa and 2MASS J09251388+6424488 (=NSVS 2497620, hereafter NSVS 2497) in BVRcIc -bands are presented and analyzed by using the 2015 version of the Wilson-Devinney (W-D) code. We found that both of them are active contact eclipsing binaries (CEBs) . At the same time, we es…
Peculiar temporal and spectral features in highly obscured HMXB pulsar IGR J16320-4751 using XMM-Newton
Paul, Biswajit; Varun; Iyer, Nirmal
IGR J16320-4751 is a highly obscured HMXB source containing a very slow neutron star (Pspin ∼ 1300 sec) orbiting its supergiant companion star with a period of ∼9 days. It shows high column density (NH ∼ 2 - 5 × 1023cm-2) in the spectrum, and a large variation in flux along the orbit despite not being an…
A Gaia based analysis of open cluster Berkeley 27
Bisht, D.; Yadav, R. K. S.; Rangwal, G. +2 more
In this paper, we have used the Gaia's Data Release-3 (DR3) data to study an intermediate-age open cluster Berkeley 27 (Be 27). A total of 131 most probable cluster members are picked within the cluster's radius based on the membership probability (> 80%). The cluster's radius was estimated as 3.74 arcmin. The mean proper motion (PM) of Be 27 w…