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We present results of a search for variable stars in a region of the globular cluster NGC 4147 based on photometric observations with 4k x 4k CCD imager mounted at the axial port of the recently installed 3.6 m Devasthal optical telescope…

We present the first results of the application of supervised classification methods to the Kepler Q1 long-cadence light curves of a subsample of 2288 stars measured in the asteroseismology program of the mission. The methods, originally…

We calculate light curves produced by a hot spot of a rapidly rotating neutron star, assuming that the spot is perturbed by a core $r$-mode, which is destabilized by emitting gravitational waves. To calculate light curves, we take account…

High Energy Astrophysical Phenomena · Physics 2015-05-19 Kazutoshi Numata , Umin Lee

The fluctuations observed in the light curves of some GRB-afterglows (such as GRB 021004) provide a useful tool to probe the circum-burst density profile and to probe the variations in the energy of blast-wave with time. We present a…

Astrophysics · Physics 2009-11-07 Ehud Nakar , Tsvi Piran

We analyze average gamma-ray variability statistics for the sample of blazars detected by CGRO/EGRET. We re-reduce all the available EGRET observations and analyze light curves by Monte Carlo modeling of the variability statistics including…

Astrophysics · Physics 2007-05-23 P. Magdziarz , R. Moderski , G. M. Madejski

The presence of r mode oscillations (global modes of Rossby waves coupled with buoyancy) in an eclipsing binary is recognized as frequency groups in a frequency-amplitude diagram obtained from a Fourier analysis of Kepler light curve data.…

Solar and Stellar Astrophysics · Physics 2019-12-03 Hideyuki Saio

DM Cyg, a fundamental mode RRab star was observed in the 2007 and 2008 seasons in the frame of the Konkoly Blazhko Survey. Very small amplitude light curve modulation was detected with 10.57 d modulation period. The maximum brightness and…

Solar and Stellar Astrophysics · Physics 2015-05-13 J. Jurcsik , Zs. Hurta , A. Sodor , B. Szeidl , I. Nagy , K. Posztobanyi , M. Varadi , K. Vida , B. Belucz , I. Dekany , G. Hajdu , Zs. Kovari , E. Kun

The photometric properties of the variable stars located in the lower part of the classical instability strip are discussed. The importance of the determination of some light curve parameters and their connection with the stellar models are…

Astrophysics · Physics 2007-05-23 Ennio Poretti , Federica Musazzi

Deep B,V time-series photometry obtained with the ESO Very Large Telescope has been used to identify variable stars in the dwarf irregular galaxy NGC 6822. We surveyed a 6.8x6.8 arcmin area of the galaxy and detected a total number of 390…

Astrophysics · Physics 2009-11-10 L. Baldacci , L. Rizzi , G. Clementini , E. V. Held

Blazhko stars from the extended $BVI_{\mathrm C}$ time series of RRab stars in the globular cluster, M3, are analysed. This is the largest sample of Blazhko stars with full details of their Blazhko properties in a homogeneous stellar…

Solar and Stellar Astrophysics · Physics 2019-10-09 Johanna Jurcsik

We present general analytic expressions for GRB afterglow light curves arising from a variable external density profile and/or a variable energy in the blast wave. The former could arise from a clumpy ISM or a variable stellar wind; The…

Astrophysics · Physics 2009-11-07 Ehud Nakar , Tsvi Piran , Jonathan Granot

The simultaneous photometric and spectroscopic observations of the RR Lyrae variables in the globular cluster, M3, published in Jurcsik et al. (2017, Paper I) made it possible to perform Baade-Wesselink (BW) analysis of a large sample of…

Solar and Stellar Astrophysics · Physics 2017-07-26 J. Jurcsik , G. Hajdu

The ratio of the depths of spectral lines is a powerful indicator of the effective temperature. The method based on this analysis is capable of discerning small temperature variations of individual stars. We apply this spectroscopic data…

Astrophysics · Physics 2007-05-23 K. Biazzo , A. Frasca , S. Catalano , E. Marilli

Visible colors (BVRI) are a reasonable proxy for real spectra of Centaurs and Kuiper Belt Objects, which are rather linear in this range. Colors provide limited information but remain the best tool to study the bulk surface properties. We…

Earth and Planetary Astrophysics · Physics 2015-05-20 Nuno Peixinho , Audrey Delsanti , Alain Doressoundiram

The amplitude and morphology of light curves of solar-like stars change substantially with increasing rotation rate: brightness variations get amplified and become more regular, which has so far not been explained. We develop a modelling…

Solar and Stellar Astrophysics · Physics 2023-04-19 N. -E. Nèmec , A. I. Shapiro , E. Işik , S. K. Solanki , T. Reinhold

We used four-year baseline HST/WFC3 IR observations of the Galactic Centre in the F153M band (1.53 micron) to identify variable stars in the central ~2.3'x2.3' field. We classified 3845 long-term (periods from months to years) and 76…

Paper I: "RR Lyrae Variables in Globular Clusters and the Second-Parameter Phenomenon" Authors: M. Catelan, A. V. Sweigart, J. Borissova Abstract: We propose to use RR Lyrae variables in globular clusters to probe the origin of the…

Astrophysics · Physics 2007-05-23 M. Catelan , A. V. Sweigart , J. Borissova , N. Spassova , V. D. Ivanov

Amplitude and period variations have been detected in almost all types of pulsating stars. Many of these modulations are nearly periodic. In RR Lyrae stars the phenomenon in known as the Blazhko Effect. Because of the observed similarities,…

Solar and Stellar Astrophysics · Physics 2010-01-26 Michel Breger

In an extended photometric campaign of RR Lyrae variables of the globular cluster M3, an aberrant light-curve, non-Blazhko RRab star, V123, was detected. Based on its brightness, colors and radial velocity curve, V123 is a bona fide member…

Solar and Stellar Astrophysics · Physics 2015-06-17 J. Jurcsik , P. Smitola , G. Hajdu , C. Pilachowski , K. Kolenberg , Á. Sódor , G. Fűrész , A. Moór , E. Kun , A. Saha , P. Prakash , P. Blum , I. Tóth

We present $V,I$ light curves for 12 variable stars identified in the newly discovered satellite of the Milky Way in the Bootes constellation (Belokurov et al. 2006).Our sample includes 11 RR Lyrae stars (5 first overtone, 5 fundamental…

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