266 citations · 1.8k across the 48 of their papers we have counts for
15 papers · 1 filter
Toward more accurate RR Lyrae metallicities
Geza Kovacs, Johanna Jurcsik
By using a large sample of published spectroscopic iron abundances, we point out the importance of gravity correction in deriving more accurate metal abundances for RR Lyrae stars.…
A Study of Stellar Spins in 15 Open Clusters
Brian F. Healy, P. R. McCullough, Kevin C. Schlaufman +1
We analyze spectroscopic and photometric data to determine the projected inclinations of stars in 11 open clusters, placing constraints on the spin-axis distributions of six cluste…
Bright single-mode RR Lyrae stars: matching Gaia EDR3 with pulsation and evolutionary models
Geza Kovacs, Behrooz Karamiqucham
We combine observed metallicity, optical and infrared magnitudes with evolutionary and pulsation models to derive average luminosities for 156 single-mode RR Lyrae stars. These lum…
Probing galactic double-mode RR Lyrae stars against Gaia EDR3
Geza Kovacs, Behrooz Karamiqucham
Classical double-mode pulsators (RR Lyrae stars and delta Cepheids) are important for their simultaneous pulsation in low-order radial modes. This enables us to put stringent const…
On the Incidence Rate of Blazhko Stars
Geza Kovacs
In a recent paper (Kovacs 2018) we examined the incidence rate of the modulated RR Lyrae stars by using the data from Campaigns 01 - 04 of the Kepler K2 mission. We found an observ…
On the hierarchical triple nature of the former red nova precursor candidate KIC 9832227
Geza Kovacs, Joel D. Hartman, Gaspar A. Bakos
We revisit the issue of period variation of the recently claimed red nova precursor candidate KIC 9832227. By using the data gathered during the main mission of the Kepler satellit…
Are all RR Lyrae stars modulated?
Geza Kovacs
We analyzed 151 variables previously classified as fundamental mode RR Lyrae stars from Campaigns 01-04 of the Kepler two wheel (K2) archive. By employing a method based on the app…
Big Signals, Small Signals, Systematics
Geza Kovacs
We examine the role of instrumental systematics in the search for small amplitude signal components in the presence of large amplitude signals. Current analyses of variable stars d…
Signature of non-isotropic distribution of stellar rotation inclination angles in the Praesepe cluster
Geza Kovacs
The distribution of the stellar rotation axes of 113 main sequence stars in the open cluster Praesepe are examined by using current photometric rotation periods, spectroscopic rota…
Synergies between Exoplanet Surveys and Variable Star Research
Geza Kovacs
With the discovery of the first transiting extrasolar planetary system back to 1999, a great number of projects started to hunt for other similar systems. Because of the incidence…
The Blazhko phenomenon
Geza Kovacs
In spite of the accumulating high quality data on RR Lyrae stars, the underlying cause of the (quasi)periodic light curve modulation (the so-called Blazhko effect) of these objects…
Are the gyro-ages of field stars underestimated?
Geza Kovacs
By using the current photometric rotational data on eight galactic open clusters, we show that the evolutionary stellar model (isochrone) ages of these clusters are tightly correla…
Stellar rotational periods in the planet hosting open cluster Praesepe
Geza Kovacs, Joel D. Hartman, Gaspar A. Bakos +6
By using the dense coverage of the extrasolar planet survey project HATNet, we Fourier analyze 381 high-probability members of the nearby open cluster Praesepe (Beehive/M44/NGC 263…
The rich frequency spectrum of the triple-mode variable AC And
G. Kovacs, G. A. Bakos, J. D Hartman
Fourier analysis of the light curve of AC And from the HATNet database reveals the rich frequency structure of this object. Above 30 components are found down to the amplitude of 3…
Study of Globular Cluster M53: new variables, distance, metallicity
Istvan Dekany, Geza Kovacs
We study the variable star content of the globular cluster M53 to compute the physical parameters of the constituting stars and the distance of the cluster. Covering two adjacent s…