Optical variability of the BL Lacertae object GC 0109+224. Multiband behaviour and time scales from a 7-years monitoring campaign

We present the most continuous data base of optical $BVR_{c}I_{c}$ observations ever published on the BL Lacertae object GC 0109+224, collected mainly by the robotic telescope of the Perugia University Observatory in the period November 1994-February 2002. These observations have been complemented by data from the Torino Observatory, collected in the period July 1995-January 1999, and Mt. Maidanak Observatory (December 2000). GC 0109+224 showed rapid optical variations and six major outbursts were observed at the beginning and end of 1996, in fall 1998, at the beginning and at the end of 2000, and at the beginning of 2002. Fast and large-amplitude drops characterized its flux behaviour. The $R_c$ magnitude ranged from 13.3 (16.16 mJy) to 16.46 (0.8 mJy), with a mean value of 14.9 (3.38 mJy). In the periods where we collected multi-filter observations, we analyzed colour and spectral indexes, and the variability patterns during some flares. The long-term behaviour seems approximatively achromatic, but during some isolated outbursts we found evidence of the typical loop-like hysteresis behaviour, suggesting that rapid optical variability is dominated by non-thermal cooling of a single emitting particle population. We performed also a statistical analysis of the data, through the discrete correlation function (DCF), the structure function (SF), and the Lomb-Scargle periodogram, to identify characteristic times scales, from days to months, in the light curves, and to quantify the mode of variability. We also include the reconstruction of the historical light curve and a photometric calibration of comparison stars, to favour further extensive optical monitoring of this interesting blazar.Comment: 13 pages, 11 PS figures, 1 EPS figure, 3 tables, accepted by Astronomy and Astrophysics. Uses A&A documentclass aa.cls, and the package graphicx.st

Taxonomy of the wild species of genus Crataegus (Rosaceae): An updated review for the flora of Nakhchivan Autonomous Republic (Azerbaijan)

We clarified the current state of genus Crataegus L. in the flora of the Nakhchivan Autonomous Republic (Azerbaijan) using a comparative analysis of herbarium specimens from the Azarbaijan herbariums and data collected during the expeditions in 2004–2018. We succeed in adding some important data on the flora of Nakhchivan Autonomous Republic and Azerbaijan, we also enhanced the previous research with chromosome and morphological analysis. We identified 17 wild species of Crataegus genus in the Nakhchivan Autonomous Republic (C. pentagyna Waldst. et Kit. ex Willd., 1800, C. zangezura Pojark., 1939, C. orientalis Pall. ex Bieb., 1808, C. pojarkoviae Kossych, 1964, C. tournefortii Griseb., 1843, C. szovitsii Pojark., 1939, C. pontica C. Koch, 1853, C. meyeri Pojark., 1939, C. eriantha Pojark., 1939, C. atrosanguinea Pojark., 1939, C. caucasica C. Koch, 1853, C. pallasii Griseb., 1843, C. rhipidophylla Gand. (С. curvisepala Lindm.; C. kyrtostyla Pojark.) 1871, C. pseudoheterophylla Pojark., 1939, C. monogyna Jacq., 1775, C. x armena Pojark., 1939, and C. x cinovskisii Kassumova), which will contribute to five introduced cultural species used in the greenery. We also clarified the status of interserial and intersection hybrids using the chromosome and morphological analysis. The article includes the complete list of Crataegus L. species with information about synonyms of the species, patterns of distribution, habitat, latitude and elevation, flowering and fruiting phenology

New species of Sorbus (Rosaceae) for the flora of the Nakhchivan Autonomous Republic (Azerbaijan)

As a result of perennial researches conducted, as well as the analysis of the herbaria materials and literature sources during expeditions to the various areas of the Nakhchivan Autonomous Republic during 2004–2017, the following new species of rowans, Sorbus albovii Zinserl., S. armeniaca Hedl., S. buschiana Zinserl., S. caucasica Zinserl., S. fedorovii Zaikonn., S. kusnetzovii Zinserl., S. migarica Zinserl. and S. tamamschjanae Gabr., were identified for the flora of the Nakhchivan Autonomous Republic. The article includes information about the synonyms of the types, regularity of distribution depending on altitude zones, bloom and ripening duration

The Angstrom Project Alert System: real-time detection of extragalactic microlensing

The Angstrom Project is undertaking an optical survey of stellar microlensing events across the bulge region of the Andromeda Galaxy (M31) using a distributed network of two-meter class telescopes. The Angstrom Project Alert System (APAS) has been developed to identify in real time candidate microlensing and transient events using data from the Liverpool and Faulkes North robotic telescopes. This is the first time that real-time microlensing discovery has been attempted outside of the Milky Way and its satellite galaxies. The APAS is designed to enable follow-up studies of M31 microlensing systems, including searches for gas giant planets in M31. Here we describe the APAS and we present a few example light curves obtained during its commissioning phase which clearly demonstrate its real-time capability to identify microlensing candidates as well as other transient sources.Comment: 4 pages, submitted to ApJ Letter

The Monitor Project: Stellar rotation at 13~Myr: I. A photometric monitoring survey of the young open cluster h~Per

We aim at constraining the angular momentum evolution of low mass stars by measuring their rotation rates when they begin to evolve freely towards the ZAMS, i.e. after the disk accretion phase has stopped. We conducted a multi-site photometric monitoring of the young open cluster h Persei that has an age of ~13 Myr. The observations were done in the I-band using 4 different telescopes and the variability study is sensitive to periods from less than 0.2 day to 20 days. Rotation periods are derived for 586 candidate cluster members over the mass range 0.4<=M/Msun<=1.4. The rotation period distribution indicates a sligthly higher fraction of fast rotators for the lower mass objects, although the lower and upper envelopes of the rotation period distribution, located respectively at ~0.2-0.3d and ~10d, are remarkably flat over the whole mass range. We combine this period distribution with previous results obtained in younger and older clusters to model the angular momentum evolution of low mass stars during the PMS. The h Per cluster provides the first statistically robust estimate of the rotational period distribution of solar-type and lower mass stars at the end of the PMS accretion phase (>10 Myr). The results are consistent with models that assume significant core-envelope decoupling during the angular momentum evolution to the ZAMS.Comment: 39 pages, 19 figures, light curves in appendix, 1 long tabl

Multi-wavelength observations of afterglow of GRB 080319B and the modeling constraints

We present observations of the afterglow of GRB 080319B at optical, mm and radio frequencies from a few hours to 67 days after the burst. Present observations along with other published multi-wavelength data have been used to study the light-curves and spectral energy distributions of the burst afterglow. The nature of this brightest cosmic explosion has been explored based on the observed properties and it's comparison with the afterglow models. Our results show that the observed features of the afterglow fits equally good with the Inter Stellar Matter and the Stellar Wind density profiles of the circum-burst medium. In case of both density profiles, location of the maximum synchrotron frequency $\nu_m$ is below optical and the value of cooling break frequency $\nu_c$ is below $X-$rays, $\sim 10^{4}$s after the burst. Also, the derived value of the Lorentz factor at the time of naked eye brightness is $\sim 300$ with the corresponding blast wave size of $\sim 10^{18}$ cm. The numerical fit to the multi-wavelength afterglow data constraints the values of physical parameters and the emission mechanism of the burst.Comment: 8 Pages, 3 Figures, Accepted for publication to Astronomy and Astrophysics on 02/04/200

Features of the formation and development of the region’s human capital in a digital transformation

At present, humanity is living in conditions of a digital transformation. The scientific and technological revolution has been replaced by an informational (digital) revolution, during which a new "information society" is being created. With the digitalization of the regions, highly educated, professionally trained human capital is gaining more and more valu

The Hot Inner Disk of FU Ori

We have constructed a detailed radiative transfer disk model which reproduces the main features of the spectrum of the outbursting young stellar object FU Orionis from ~ 4000 angstrom, to ~ 8 micron. Using an estimated visual extinction Av~1.5, a steady disk model with a central star mass ~0.3 Msun and a mass accretion rate ~ 2e-4 Msun/yr, we can reproduce the spectral energy distribution of FU Ori quite well. With the mid-infrared spectrum obtained by the Infrared Spectrograph (IRS) on board the Spitzer Space Telescope, we estimate that the outer radius of the hot, rapidly accreting inner disk is ~ 1 AU using disk models truncated at this outer radius. Inclusion of radiation from a cooler irradiated outer disk might reduce the outer limit of the hot inner disk to ~ 0.5 AU. In either case, the radius is inconsistent with a pure thermal instability model for the outburst. Our radiative transfer model implies that the central disk temperature Tc > 1000 K out to ~ 0.5 - 1 AU, suggesting that the magnetorotational instability (MRI) can be supported out to that distance. Assuming that the ~ 100 yr decay timescale in brightness of FU Ori represents the viscous timescale of the hot inner disk, we estimate the viscosity parameter (alpha) to be ~ 0.2 - 0.02 in the outburst state, consistent with numerical simulations of MRI in disks. The radial extent of the high mass accretion region is inconsistent with the model of Bell & Lin, but may be consistent with theories incorporating both gravitational instability and MRI.Comment: 32 pages, 10 figures, to appear in the Astrophysical Journa