A5048610299- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Gamma-ray bursts and supernovae
- Scientific Research and Discoveries
- Astrophysical Phenomena and Observations
- Astronomical Observations and Instrumentation
- Geophysics and Gravity Measurements
- Pulsars and Gravitational Waves Research
- Astrophysics and Star Formation Studies
- Astro and Planetary Science
- Geomagnetism and Paleomagnetism Studies
- History and advancements in chemistry
- Galaxies: Formation, Evolution, Phenomena
- Chemistry and Stereochemistry Studies
- Cosmology and Gravitation Theories
- Inorganic Fluorides and Related Compounds
- Earth Systems and Cosmic Evolution
- Complex Systems and Time Series Analysis
- Nuclear physics research studies
- Geophysics and Sensor Technology
Tel Aviv University
2018-2023
Gaia DR3 contains 1.8 billion sources with G-band photometry, 1.5 of which BP and RP complemented by positions on the sky, parallax, proper motion. The median number field-of-view transits in three photometric bands is between 40 44 measurements per source covers 34 months data collection. We pursue a classification Galactic extra-galactic objects that are detected as variable across whole sky. Supervised machine learning (eXtreme Gradient Boosting Random Forest) was employed to generate...
We present a homogeneously-selected sample of 15779 candidate binary systems with main sequence primary stars and orbital periods shorter than 5 days. The targets were selected from TESS full-frame image lightcurves on the basis their tidally-induced ellipsoidal modulation. Spectroscopic follow-up suggests purity $83 \pm 13$ per cent. Injection-recovery tests allow us to estimate our overall completeness as $28 3$ cent $P_\mathrm{orb} < days quantify selection effects. that $39 4$ are...
Ellipsoidal variables present light-curve modulations caused by stellar distortion, induced tidal interaction with their companions. An analytical approximated model of the ellipsoidal modulation is given as a discrete Fourier series Morris and Naftilan 1993 (MN93). Based on numerical simulations using PHOEBE code we here updated amplitudes first three harmonics model. The expected are function mass ratio inclination binary system fillout factor primary---the between radius that its Roche...
We have identified 2XMM J125556.57+565846.4, at a distance of 600 pc, as binary system consisting normal star and probable dormant neutron star. Optical spectra exhibit slightly evolved F-type single star, displaying periodic Doppler shifts with 2.76-day Keplerian circular orbit, no indication light from secondary component. UV photometry reveal ellipsoidal variations half the orbital period, due to tidal deformation F The mass unseen companion is constrained range $1.1$--$2.1\,M_{\odot}$...
Context. The space telescope Gaia is mainly dedicated to performing high-precision astrometry but also used perform spectroscopy and epoch photometry, which can be study various types of photometric variability. One such variability type exoplanetary transits. data accumulated so far have finally matured enough allow the detection some exoplanets. Aims. In order fully exploit scientific potential Gaia, we search its for signatures Methods. relies on a version box-fitting least-squares...
This is the second of a series papers that focuses on searching large sets photometric light curves for evidence close binaries with dormant black hole, and, in some cases, neutron star. The detection such binary based identifying star displays ellipsoidal periodic modulation, induced by tidal interaction its companion. Based observed amplitude and primary mass radius, one can derive minimum ratio binary. A significantly larger than unity might be candidate having compact-object...
ABSTRACT This is the third of a series papers that presents an algorithm to search for close binaries with massive, possibly compact, unseen secondaries. The detection such binary based on identifying star displays large ellipsoidal periodic modulation, induced by tidal interaction its companion. In second paper series, we presented simple approach derive robust modified minimum mass ratio (mMMR), observed amplitude, without knowing primary and radius, assuming fills Roche lobe. newly...
Gaia DR3 contains 1.8 billion sources with G-band photometry, 1.5 of which BP and RP complemented by positions on the sky, parallax, proper motion. The median number field-of-view transits in three photometric bands is between 40 44 measurements per source covers 34 months data collection. We pursue a classification Galactic extra-galactic objects that are detected as variable across whole sky. Supervised machine learning (eXtreme Gradient Boosting Random Forest) was employed to generate...
When dealing with galactic dynamics, or more specifically, rotation curves, one basic assumption is always taken: the frame of reference relative to which rotational velocities are given assumed be inertial. In other words, fictitious forces vanish observational a galaxy. It might interesting, however, explore outcomes dropping that assumption; is, search for signatures non-inertial behavior in observed data. this work, we show very discrepancy galaxy curves could attributed effects. We...
When dealing with galactic dynamics, or more specifically, rotation curves, one basic assumption is always taken: the frame of reference relative to which rotational velocities are given assumed be inertial. In other words, fictitious forces vanish observational a galaxy. It might interesting, however, explore outcomes dropping that assumption; is, search for signatures non-inertial behavior in observed data. this work, we show very discrepancy galaxy curves could attributed effects. We...
We have identified 2XMM J125556.57+565846.4, at a distance of 600 pc, as binary system consisting normal star and probable dormant neutron star. Optical spectra exhibit slightly evolved F-type single star, displaying periodic Doppler shifts with 2.76-day Keplerian circular orbit, no indication light from secondary component. UV photometry reveal ellipsoidal variations half the orbital period, due to tidal deformation F The mass unseen companion is constrained range $1.1$--$2.1\,M_{\odot}$...
We present a homogeneously-selected sample of 15779 candidate binary systems with main sequence primary stars and orbital periods shorter than 5 days. The targets were selected from TESS full-frame image lightcurves on the basis their tidally-induced ellipsoidal modulation. Spectroscopic follow-up suggests purity $83 \pm 13$ per cent. Injection-recovery tests allow us to estimate our overall completeness as $28 3$ cent $P_\mathrm{orb} < days quantify selection effects. that $39 4$ are...
In this work we try a new approach for dealing with the discrepancy between observed galaxy rotation curves and theoretical predictions. This does not involve any changes in current fundamental laws of nature or addition dark halos. Rather, it is based on following single assumption: velocities presented are given relative to galaxies' local inertial frames. Another way putting down: fictitious forces, which arise non-inertial frames, should be taken into account when constructing curve. It...
We report here on a detailed study of c-type RR Lyrae variable (RRc variable), SB 796, serendipitously discovered in search the WASP public data for stars that display large photometric periodic modulation. 796 displays period $P = 0.26585$ d and semi-amplitude $\sim$ 0.1 mag. Comparison modulation shape with analysis LMC variables indicates is an RRc variable. Gaia DR2 classification corroborated our result. Radial-velocity (RV) follow-up observations revealed variation consistent sine...
When dealing with galactic dynamics, or more specifically, rotation curves, one basic assumption is always taken: the frame of reference relative to which rotational velocities are given assumed be inertial. In other words, fictitious forces vanish observational a galaxy. It might interesting, however, explore outcomes dropping that assumption; is, search for signatures non-inertial behavior in observed data. this work, we show very discrepancy galaxy curves could attributed effects. We...