Astrophysical Bulletin最新文献

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Stellar photometry of 24 dwarf galaxies was carried out using the archival images of the Hubble Space Telescope. The resulting Hertzsprung–Russell diagrams reveal branches of young and old stars. Using the results of photometry and applying the TRGB method, we have for the first time determined exact distances to 13 galaxies. Galaxy PGC 704814 is located at the closest distance ((D = 3.73) Mpc), while SDSS J115 840.37+153 533.7 is located the farthest from us ((D = 11.95) Mpc). The distances to other galaxies lie in the range from 7 to 11 Mpc. The object SDSS J140 457.78+534 128.2, as follows from the distribution of red giants, is not a galaxy, but rather a young star complex on the periphery of the neighboring galaxy NGC 5474.

Abstract—Based on high-precision data from the archive of the TESS space mission, a study was made of the photometric brightness variability of TOI 837—a young star with an exoplanet, a member of the southern sky cluster IC 2602. Based on all available observational results, we have estimated the star’s rotation period and brightness variability amplitude, and also estimated the absolute value of the spottedness parameter (A) using the standard method. The area of spots on the surface of TOI 837 is from 21 600 up to 37 700 MSH and significantly exceeds the area of sunspots. The estimates were obtained for the effective temperature of the star ({{T}_{{{text{eff}}}}} = 6047 pm 162) K and radius (R = 1.022{kern 1pt} {{R}_{ odot }}). The manifestations of the TOI 837 flare activity in the observation interval in four sectors of the TESS space mission are studied and the two most reliable flares recorded are considered. The flare energies are (1.2 times {{10}^{{35}}}) erg and (2.1 times {{10}^{{35}}}) erg, and the probable value of the mass of the accompanying coronal mass ejection may reach ({{10}^{{21.4}}}) g. We have estimated the most probable value of the TOI 837 activity cycle: it is 1500 days (4.1 years). A distinctive feature of TOI 837 b (as well as other exoplanets less than 100 million years old) is that its position on the diagrams “planet radius–age” and “planet radius–period of the planet’s rotation” does not overlap with populations of hot Jupiters and sub-Neptunes.

Abstract—The design and functions of the main component of the automated complex for the study of astrophysical objects with high time resolution at the 6-m telescope of SAO RAS—a permanently available photopolarimeter installed at the N1 focus of the BTA for alert observations of optical transient sources are described. The device operates in several modes (up to six in perspective)—spectral, polarimetric, photometric, the choice of which is determined after real-time analysis of the image of the object localization area, recorded in the subview with a field of view of (2mathop .limits^prime 5 times 3'). The radiation from the vicinity of the detected source is transferred to a diaphragm of variable size from (10'' times 10'') to (60'' times 10'') and, depending on its brightness, passed through one of the (UBVR) filters or dispersed by the Abbe prism, is recorded by the EMCCD with a time resolution of 0.1 s. In this case, it is possible to introduce a double Wollaston prism into the input beam, which ensures the measurement of the object’s linear polarization. To compensate for the rotation of the instrument’s field of view during observations on the balcony of the N1 focus, a turntable is used, the position of which is set by the telescope’s control system. Control of the observation process, selection and change of modes is carried out using a graphical interface. The automatic implementation of these operations is being tested.

Abstract—We present new results of the study of ET Dra—a star of the FK Com type—based on observations carried out at the Zvenigorod Observatory of the Institute of Astronomy of RAS with the help of the FRAM-ORM telescope of the La Palma observatory (Spain) and the broadband optical monitoring system Mini-MegaTORTORA, located on the territory of the SAO RAS. We have studied changes in the shape of the light curve caused by the rotational modulation of a star with spots on its surface and the long-term variability of the star’s brightness. An independent determination of the rotation period of ({{P}_{{{text{phot}}}}}) was carried out using all sets of observations available to us. The increase in the brightness of the star near HJD 2459044 during observations with the FRAM-ORM telescope in all three filters was interpreted by us as a stellar flare. Our flare energy estimates are (2.8 times {{10}^{{37}}}), (1.9 times {{10}^{{37}}}), and (1.5 times {{10}^{{37}}}) erg in the (B), (V), and (R) wavelength ranges, respectively. Observations with a duration of more than 2200 days, carried out at the SAO RAS, opened up the possibility of analyzing the long-term brightness variability of ET Dra. Evidence was found for the existence of cycles lasting 580 days and 810 days (1.55 and 2.23 years, respectively).

Abstract—We undertook a search for new dwarf galaxies in the vicinity of relatively isolated nearby galaxies with distances (D < 12) Mpc and stellar masses in the ((2 times {{10}^{{11}}})–(3 times {{10}^{8}} {{M}_{ odot }})) interval, using the data from the DESI Legacy Imaging Surveys. Around the 46 considered Local Volume galaxies, (67) new candidates for satellites of these galaxies were found. About half of them are classified as spheroidal dwarfs of low surface brightness. The new galaxies are included in the Local Volume database (LVGDB), which now contains 1421 objects, being 63% more than the Updated Nearby Galaxy Catalog.

Abstract—We present the first part of the survey of the results of spectroscopic observations of mirides in the optical and near infrared ranges. The main phenomenological schemes and models are listed. The published results are supplemented by spectroscopic observations and calculations performed at the SAO RAS.

Abstract—We describe a new wide-field GPIXEL 9 K ( times ) 9 K, CMOS and compare it with foreign-made chips of similar size. We report the parameters of the advanced NEVA9090 wide-field detector based on this CMOS and manufactured by NPK Fotonika. The camera can be used as a detector for modern high-performance wide-field telescopes. We present the parameters of a telescope with an aperture of 1 m and a focal ratio of (F:1.3) when operated with the new NEVA9090 camera.