Search for and study of photometric variability in magnetic white dwarfs

© 2017, Pleiades Publishing, Ltd.We report the results of photometric observations of a number of magnetic white dwarfs in order to search for photometric variability in these stars. These V-band observations revealed significant variability in the classical highly magnetized white dwarf GRW+70◦8247 with a likely period from several days to several dozen days and a half-amplitude of about 0.m 04. Our observations also revealed the variability of the well-known white dwarf GD229. The half amplitude of its photometric variability is equal to about 0.m 005, and the likely period of this degenerate star lies in the 10–20 day interval. This variability is most likely due to the rotation of the stars considered.We also discuss the peculiarities of the photometric variability in a number of other white dwarfs. We present the updated “magnetic field–rotation period” diagram for the white dwarfs

Search for and study of photometric variability in magnetic white dwarfs

© 2017, Pleiades Publishing, Ltd.We report the results of photometric observations of a number of magnetic white dwarfs in order to search for photometric variability in these stars. These V-band observations revealed significant variability in the classical highly magnetized white dwarf GRW+70◦8247 with a likely period from several days to several dozen days and a half-amplitude of about 0.m 04. Our observations also revealed the variability of the well-known white dwarf GD229. The half amplitude of its photometric variability is equal to about 0.m 005, and the likely period of this degenerate star lies in the 10–20 day interval. This variability is most likely due to the rotation of the stars considered.We also discuss the peculiarities of the photometric variability in a number of other white dwarfs. We present the updated “magnetic field–rotation period” diagram for the white dwarfs

Search for and study of photometric variability in magnetic white dwarfs

© 2017, Pleiades Publishing, Ltd.We report the results of photometric observations of a number of magnetic white dwarfs in order to search for photometric variability in these stars. These V-band observations revealed significant variability in the classical highly magnetized white dwarf GRW+70◦8247 with a likely period from several days to several dozen days and a half-amplitude of about 0.m 04. Our observations also revealed the variability of the well-known white dwarf GD229. The half amplitude of its photometric variability is equal to about 0.m 005, and the likely period of this degenerate star lies in the 10–20 day interval. This variability is most likely due to the rotation of the stars considered.We also discuss the peculiarities of the photometric variability in a number of other white dwarfs. We present the updated “magnetic field–rotation period” diagram for the white dwarfs

Search for and study of photometric variability in magnetic white dwarfs

© 2017, Pleiades Publishing, Ltd.We report the results of photometric observations of a number of magnetic white dwarfs in order to search for photometric variability in these stars. These V-band observations revealed significant variability in the classical highly magnetized white dwarf GRW+70◦8247 with a likely period from several days to several dozen days and a half-amplitude of about 0.m 04. Our observations also revealed the variability of the well-known white dwarf GD229. The half amplitude of its photometric variability is equal to about 0.m 005, and the likely period of this degenerate star lies in the 10–20 day interval. This variability is most likely due to the rotation of the stars considered.We also discuss the peculiarities of the photometric variability in a number of other white dwarfs. We present the updated “magnetic field–rotation period” diagram for the white dwarfs

Massive search of spot- and facula-crossing events in 1598 exoplanetary transit lightcurves

We developed a dedicated statistical test for a massive detection of spot- A nd facula-crossing anomalies in multiple exoplanetary transit light curves, based on the frequentist p-value thresholding. This test was used to augment our algorithmic pipeline for transit light curves analysis. It was applied to 1598 amateur and professional transit observations of 26 targets being monitored in the EXPANSION project. We detected 109 statistically significant candidate events revealing a roughly 2 : 1 asymmetry in favor of spots-crossings over faculae-crossings. Although some candidate anomalies likely appear non-physical and originate from systematic errors, such asymmetry between negative and positive events should indicate a physical difference between the frequency of star spots and faculae. Detected spot-crossing events also reveal positive correlation between their amplitude and width, possibly due to spot size correlation. However, the frequency of all detectable crossing events appears just about a few per cent, so they cannot explain excessive transit timing noise observed for several targets.Fil: Baluev, R. V.. Saint Petersburg State University; RusiaFil: Sokov, E. N.. Saint Petersburg State University; Rusia. Russian Academy of Sciences. Central Astronomical Observatory at Pulkovo; RusiaFil: Sokova, I. A.. Saint Petersburg State University; Rusia. Russian Academy of Sciences. Central Astronomical Observatory at Pulkovo; RusiaFil: Shaidulin, V. Sh.. Saint Petersburg State University; RusiaFil: Veselova, A. V.. Saint Petersburg State University; RusiaFil: Aitov, V. N.. Russian Academy of Sciences. Special Astrophysical Observatory; RusiaFil: Mitiani, G. Sh.. Russian Academy of Sciences. Special Astrophysical Observatory; RusiaFil: Valeev, A. F.. Russian Academy of Sciences. Special Astrophysical Observatory; Rusia. Russian Academy of Sciences. Crimean Astrophysical Observatory; RusiaFil: Gadelshin, D.R.. Russian Academy of Sciences. Special Astrophysical Observatory; RusiaFil: Gutaev, A. G.. Russian Academy of Sciences. Special Astrophysical Observatory; Rusia. KazanFederal University (Volga Region); RusiaFil: Beskin, G.M.. Russian Academy of Sciences. Special Astrophysical Observatory; Rusia. KazanFederal University (Volga Region); RusiaFil: Valyavin, G. G.. Russian Academy of Sciences. Special Astrophysical Observatory; Rusia. Russian Academy of Sciences. Crimean Astrophysical Observatory; Rusia. Saint Petersburg State University; RusiaFil: Antonyuk, K.. Russian Academy of Sciences. Crimean Astrophysical Observatory; RusiaFil: Barkaoui, K.. Université de Liège; Bélgica. Cadi Ayyad University; MarruecosFil: Gillon, M.. Université de Liège; BélgicaFil: Jehin, E.. Université de Liège; BélgicaFil: Delrez, L.. Université de Liège; BélgicaFil: Gumundsson, S.. Nes Observatory; IslandiaFil: Dale, H. A.. University of Emory; Estados UnidosFil: Fernandez Lajus, Eduardo Eusebio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Di Sisto, Romina Paula. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Bretton, M.. Baronnies Provençales Observatory; FranciaFil: Wunsche, A.. Baronnies Provençales Observatory; FranciaFil: Hentunen, V. P.. Taurus Hill Observatory; FinlandiaFil: Shadick, S.. University of Saskatchewan; CanadáFil: Jongen, Y.. Observatoire de Vaison la Romaine; FranciaFil: Kang, W.. National Youth Space Center; Corea del SurFil: Kim, T.. National Youth Space Center; Corea del Sur. Chungbuk National University; Corea del SurFil: Pakštienė, E.. Vilnius University; LituaniaFil: Qvam, J. K. T.. Horten Videregående Skole; Norueg

EXPLANATION: Exoplanet and Transient Event Investigation Project—Optical Facilities and Solutions

Peer reviewed: TrueOver the past decades, the achievements in astronomical instrumentation have given rise to a number of novel advanced studies related to the analysis of large arrays of observational data. One of the most famous of these studies is a study of transient events in the near and far space and a search for exoplanets. The main requirements for such kinds of projects are a simultaneous coverage of the largest possible field of view with the highest possible detection limits and temporal resolution. In this study, we present a similar project aimed at creating an extensive, continuously updated survey of transient events and exoplanets. To date, the core of the project incorporates several 0.07–2.5 m optical telescopes and the 6-m BTA telescope of the Special Astrophysical Observatory of RAS (Russia), a number of other Russian observatories and the Bonhyunsan observatory of the Korea Astronomy and Space Science Institute (South Korea). Our attention is mainly focused on the description of two groups of small, wide-angle optical telescopes for primary detection. All the telescopes are originally designed for the goals of the project and may be of interest to the scientific community. A description is also given for a new, high-precision optical spectrograph for the Doppler studies of transient and exoplanet events detected within the project. We present here the philosophy, expectations and first results obtained during the first year of running the project.</jats:p

Massive Search for Spot- and Facula-Crossing Events in 1598 Exoplanetary Transit Light Curves

We developed a dedicated statistical test for a massive detection of spot- and facula-crossing anomalies in multiple exoplanetary transit light curves, based on the frequentist p-value thresholding. This test was used to augment our algorithmic pipeline for transit light curves analysis. It was applied to 1598 amateur and professional transit observations of 26 targets being monitored in the EXPANSION project. We detected 109 statistically significant candidate events revealing a roughly 2:1 asymmetry in favor of spots-crossings over faculae-crossings. Although some candidate anomalies likely appear non-physical and originate from systematic errors, such asymmetry between negative and positive events should indicate a physical difference between the frequency of star spots and faculae. Detected spot-crossing events also reveal positive correlation between their amplitude and width, possibly due to spot size correlation. However, the frequency of all detectable crossing events appears just about a few per cent, so they cannot explain excessive transit timing noise observed for several targets

Full orbital solution for the binary system in the northern Galactic disc microlensing event Gaia16aye

© ESO 2020. Gaia16aye was a binary microlensing event discovered in the direction towards the northern Galactic disc and was one of the first microlensing events detected and alerted to by the Gaia space mission. Its light curve exhibited five distinct brightening episodes, reaching up to I? =? 12 mag, and it was covered in great detail with almost 25 000 data points gathered by a network of telescopes. We present the photometric and spectroscopic follow-up covering 500 days of the event evolution. We employed a full Keplerian binary orbit microlensing model combined with the motion of Earth and Gaia around the Sun to reproduce the complex light curve. The photometric data allowed us to solve the microlensing event entirely and to derive the complete and unique set of orbital parameters of the binary lensing system. We also report on the detection of the first-ever microlensing space-parallax between the Earth and Gaia located at L2. The properties of the binary system were derived from microlensing parameters, and we found that the system is composed of two main-sequence stars with masses 0.57 ± 0.05 M? and 0.36 ± 0.03 M? at 780 pc, with an orbital period of 2.88 years and an eccentricity of 0.30. We also predict the astrometric microlensing signal for this binary lens as it will be seen by Gaia as well as the radial velocity curve for the binary system. Events such as Gaia16aye indicate the potential for the microlensing method of probing the mass function of dark objects, including black holes, in directions other than that of the Galactic bulge. This case also emphasises the importance of long-term time-domain coordinated observations that can be made with a network of heterogeneous telescopes

Full orbital solution for the binary system in the northern Galactic disc microlensing event Gaia16aye

Gaia16aye was a binary microlensing event discovered in the direction towards the northern Galactic disc and was one of the first microlensing events detected and alerted to by the Gaia space mission. Its light curve exhibited five distinct brightening episodes, reaching up to I = 12 mag, and it was covered in great detail with almost 25 000 data points gathered by a network of telescopes. We present the photometric and spectroscopic follow-up covering 500 days of the event evolution. We employed a full Keplerian binary orbit microlensing model combined with the motion of Earth and Gaia around the Sun to reproduce the complex light curve. The photometric data allowed us to solve the microlensing event entirely and to derive the complete and unique set of orbital parameters of the binary lensing system. We also report on the detection of the first-ever microlensing space-parallax between the Earth and Gaia located at L2. The properties of the binary system were derived from microlensing parameters, and we found that the system is composed of two main-sequence stars with masses 0.57 +/- 0.05 M-circle dot and 0.36 +/- 0.03 M-circle dot at 780 pc, with an orbital period of 2.88 years and an eccentricity of 0.30. We also predict the astrometric microlensing signal for this binary lens as it will be seen by Gaia as well as the radial velocity curve for the binary system. Events such as Gaia16aye indicate the potential for the microlensing method of probing the mass function of dark objects, including black holes, in directions other than that of the Galactic bulge. This case also emphasises the importance of long-term time-domain coordinated observations that can be made with a network of heterogeneous telescopes