112 citations · 1.1k across the 55 of their papers we have counts for
38 papers · 1 filter
Finding the elusive RR Lyrae companions via speckle imaging
R. Salinas, V. Kalari, G. Hajdu +25
Despite their key role in astrophysics, the binary properties of RR Lyrae stars (RRL) remain almost completely unknown since only a single RRL is confirmed as belonging to a binary…
Period-Luminosity Relations, projection factor and radii of Anomalous Cepheids
Piotr Wielgórski, Grzegorz Pietrzyński, Wolfgang Gieren +24
Anomalous Cepheids are radially pulsating stars observed in dwarf galaxies, the Galactic bulge and halo, and globular clusters. Similarly to other radially pulsating stars, they ca…
Photometric metallicities of fundamental-mode RR Lyr stars from Gaia -band photometry of globular-cluster variables
Johanna Jurcsik, Gergely Hajdu
Photometric metallicity formulae of fundamental-mode RR Lyr (RRab) stars are presented using globular-cluster data exclusively. The aim is to check whether this selection may help…
New Near-Infrared Period-Luminosity-Metallicity Relations for Galactic RR Lyrae Stars Based on Gaia EDR3 Parallaxes
Bartłomiej Zgirski, Grzegorz Pietrzyński, Marek Górski +13
We present new period-luminosity and period-luminosity-metallicity relations for Galactic RR Lyrae stars based on a sample of 28 pulsators located at distances up to kpc from…
HARPS-N high spectral resolution observations of Cepheids II. The impact of the surface-brightness color relation on the Baade-Wesselink projection factor of eta Aql
N. Nardetto, W. Gieren, J. Storm +16
The Baade-Wesselink (BW) method of distance determination of Cepheids is used to calibrate the distance scale. Various versions of this method are mainly based on interferometry an…
Discovery of a binary-origin classical Cepheid in a binary system with a 59-day orbital period
Bogumił Pilecki, Ian B. Thompson, Felipe Espinoza-Arancibia +8
We report the discovery of a surprising binary configuration of the double-mode Cepheid OGLE-LMC-CEP-1347 pulsating in the first (P_1=0.690d) and second overtone (P_2=0.556d) modes…
Evolved eclipsing binary systems in the Galactic bulge: Precise physical and orbital parameters of OGLE-BLG-ECL-305487 and OGLE-BLG-ECL-116218
K. Suchomska, D. Graczyk, C. Gałan +17
Our goal is to determine, with high accuracy, the physical and orbital parameters of two double-lined eclipsing binary systems, where the components are two giant stars. We also ai…
Period Change Rates of Large Magellanic Cloud Cepheids using MESA
F. Espinoza-Arancibia, M. Catelan, G. Hajdu +8
Pulsating stars, such as Cepheids and RR Lyrae, offer us a window to measure and study changes due to stellar evolution. In this work, we study the former by calculating a set of e…
Surface brightness-colour relations of dwarf stars from detached eclipsing binaries -- I. Calibrating sample
D. Graczyk, G. Pietrzyński, C. Galan +19
Surface brightness -- colour relations (SBCRs) are very useful tools for predicting the angular diameters of stars. They offer the possibility to calculate very precise spectrophot…
Synthetic population of binary Cepheids. I. The effect of metallicity and initial parameter distribution on characteristics of Cepheids' companions
Paulina Karczmarek, Radosław Smolec, Gergely Hajdu +5
The majority of classical Cepheids are binary stars, yet the contribution of companions' light to the total brightness of the system has been assumed negligible and lacked a thorou…
An absolute calibration of the near-infrared Period-Luminosity Relations of Type II Cepheids in the Milky Way and in the Large Magellanic Cloud
Piotr Wielgórski, Grzegorz Pietrzyński, Bogumił Pilecki +29
We present time-series photometry of 21 nearby Type II Cepheids in the near-infrared J, H and Ks passbands. We use this photometry, together with the Third Gaia Early Data Release…
Period Change Rates in Large Magellanic Cloud Cepheids Revisited
N. Rodríguez-Segovia, G. Hajdu, M. Catelan +10
The period-change rate (PCR) of pulsating variable stars is a useful probe of changes in their interior structure, and thus of their evolutionary stages. So far, the PCRs of Classi…
Studies of RR Lyrae Variables in Binary Systems. I.: Evidence of a Trimodal Companion Mass Distribution
Gergely Hajdu, Grzegorz Pietrzyński, Johanna Jurcsik +6
We present 87 candidates for RR Lyrae variable stars in binary systems, based on our new search using the light-travel time effect (LTTE) and observed - calculated () diagrams…
On the photometric metallicity of Oosterhoff-type I and II RRab stars
Johanna Jurcsik, Gergely Hajdu, Áron Juhász
We are revising the consistency of photometric metallicity formulae widely used for fundamental-mode RR Lyrae (RRab) variables, based on their V- and I-band light curves, published…
The surface brightness - colour relations based on eclipsing binary stars and calibrated with Gaia EDR3
D. Graczyk, G. Pietrzyński, C. Gałan +23
The surface brightness -- colour relation (SBCR) is a basic tool in establishing precise and accurate distances within the Local Group. Detached eclipsing binary stars with accurat…
Into the Darkness: Classical and Type II Cepheids in the Zona Galactica Incognita
István Dékány, Gergely Hajdu, Eva K. Grebel +1
The far side of the Milky Way's disk is one of the most concealed parts of the known Universe due to extremely high interstellar extinction and point source density toward low Gala…
New Galactic multi-mode Cepheids from the ASAS-SN Survey
Johanna Jurcsik, Gergely Hajdu, Márcio Catelan
A systematic search for multi-mode Cepheids using the database of the ASAS-SN survey has led to the detection of thirteen new double-mode and two triple-mode Cepheids in the Galact…
Milky Way metallicity gradient from Gaia DR2 F/1O double-mode Cepheids
Bertrand Lemasle, Gergely Hajdu, Valery Kovtyukh +8
The ratio of the first overtone (1O) / fundamental (F) periods of mixed-mode Cepheids that pulsate simultaneously in these two modes (F/1O) is metallicity-dependent. It can therefo…
A Near-infrared RR Lyrae census along the southern Galactic plane: the Milky Way's stellar fossil brought to light
István Dékány, Gergely Hajdu, Eva K. Grebel +5
RR Lyrae stars (RRLs) are tracers of the Milky Way's fossil record, holding valuable information on its formation and early evolution. Owing to the high interstellar extinction end…
A Data-driven Study of RR Lyrae Near-IR Light Curves: Principal Component Analysis, Robust Fits, and Metallicity Estimates
Gergely Hajdu, István Dékány, Márcio Catelan +2
RR~Lyrae variables are widely used tracers of Galactic halo structure and kinematics, but they can also serve to constrain the distribution of the old stellar population in the Gal…
Blazhko modulation in the infrared
J. Jurcsik, G. Hajdu, I. Dékány +3
We present first direct evidence of modulation in the -band of Blazhko-type RR Lyrae stars that are identified by their secular modulations in the I-band data of OGLE-IV. A meth…
The first Baade-Wesselink analysis of Blazhko RR Lyrae stars: discrepancies between photometrically and spectroscopically determined radius variations
J. Jurcsik, G. Hajdu
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 p…
Photometric and radial-velocity time-series of RR Lyrae stars in M3: analysis of single-mode variables
J. Jurcsik, P. Smitola, G. Hajdu +18
We present the first simultaneous photometric and spectroscopic investigation of a large set of RR Lyrae variables in a globular cluster. The radial-velocity data presented compris…
Multi-wavelength study of the low-luminosity outbursting young star HBC 722
Á. Kóspál, P. Ábrahám, J. A. Acosta-Pulido +22
HBC 722 (V2493 Cyg) is a young eruptive star in outburst since 2010. It is an FU Orionis-type object with an atypically low outburst luminosity. Because it was well characterized i…