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The New Ephemeris and Light Curve Analysis of V870 Ara by the Ground-Based and TESS Data
DOI: 10.1515/astro-2021-0004 Bibcode: 2021OAst...30...37P

Davoudi, Fatemeh; Poro, Atila; Blackford, Mark G. +4 more

New CCD photometric observations and their investigation of the W UMa-type binary, V870 Ara, are presented. Light curves of the system were taken through BVIfilters from the Congarinni Observatory in Australia. The new ephemeris is calculated based on seven new determined minimum times, together with the TESS data and others compiled from the lite…

2021 Open Astronomy
Gaia 5
Application of clustering algorithm to wide stellar pairs for unsupervised search of parts of disrupting clusters
DOI: 10.1515/astro-2021-0025 Bibcode: 2021OAst...30..191S

Kovaleva, Dana; Sapozhnikov, Sergei

We introduce the application of the clustering algorithm to the preliminary compiled list of probable wide pairs of co-moving stars. The main aim of such development is a possibility of unsupervised blind search of coeval loose stellar structures over significant regions in space. Using Gaia EDR3 data, we investigated the application of the method…

2021 Open Astronomy
Gaia 4
Fitting procedure for estimating interstellar extinction at high galactic latitudes
DOI: 10.1515/astro-2021-0022 Bibcode: 2021OAst...30..168A

Malkov, Oleg; Kovaleva, Dana; Avdeeva, Aleksandra +1 more

We determine the interstellar extinction in the selected high-latitude areas of the sky based on Gaia EDR3 astrometry and photometry and spectroscopic data from RAVE survey. We approximate the results with the cosecant law in each area thus deriving the parameters of the barometric formula for different lines of sight. The distribution of the para…

2021 Open Astronomy
Gaia 4
A possible nonthermal X-ray emission from γ Cas analogues stars
DOI: 10.1515/astro-2021-0018 Bibcode: 2021OAst...30..132R

Ryspaeva, Elizaveta B.; Kholtygin, Alexander F.

We analyze the archival XMM-Newton X-ray observations of 15 γ Cas analogue stars and two candidates for such objects. The EPIC spectra of the considered stars in the range of 0.2-8 keV were extracted and fitted by different models. Our estimates show that assuming the X-ray emission from γ Cas analogues to be totally thermal, their model plasma te…

2021 Open Astronomy
XMM-Newton 3
Astrometry and photometry of digitized plates of Baldone Schmidt telescope
DOI: 10.1515/astro-2021-0002 Bibcode: 2021OAst...30...12E

Eglitis, Ilgmars; Andruk, Vitaly

During the 40-year photographic period of astronomical observations, the Baldone Astrophysical Observatory has accumulated more than 22,000 direct and 2,500 spectral images. In 2018, the digitization of direct astrophoto images with a resolution of 1200 dpi was completed. A processing methodology for obtaining the equatorial coordinates and photom…

2021 Open Astronomy
Hipparcos 2