Ksenia Suchomska - Academia.edu (original) (raw)
Papers by Ksenia Suchomska
Astronomy & Astrophysics
Aims. Our goal is to determine, with high accuracy, the physical and orbital parameters of two do... more Aims. 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 aim to study the evolutionary status of the binaries, to derive the distances towards them by using a surface brightness-colour relation, and to compare these measurements with the measurements presented by the Gaia mission. Methods. In order to measure the physical and orbital parameters of the systems, we analysed the light curves and radial-velocity curves with the Wilson-Devinney code. We used V-band and I-band photometry from the Optical Gravitational Lensing Experiment (OGLE) catalogue and near-infrared photometry obtained with the New Technology Telescope (NTT) equipped with the SOFI instrument. The spectroscopic data were collected with the High Accuracy Radial velocity Planet Searcher (HARPS) spectrograph mounted at the ESO 3.6-m telescope and the Magellan Inamori Kyocera Echelle (MIKE) spectrograph mounted at the 6.5-m Clay telescope. Results. We present the first analysis of this kind for two evolved eclipsing binary systems from the OGLE catalogue: OGLE-BLG-ECL-305487 and OGLE-BLG-ECL-116218. The masses of the components of OGLE-BLG-ECL-305487 are M 1 = 1.059 ± 0.019 and M 2 = 0.991 ± 0.018 M , and the radii are R 1 = 19.27 ± 0.28 and R 2 = 29.99 ± 0.24 R. For OGLE-BLG-ECL-116218, the masses are M 1 = 0.969 ± 0.012 and M 2 = 0.983 ± 0.012 M , while the radii are R 1 = 16.73 ± 0.28 and R 2 = 22.06 ± 0.26 R. The evolutionary status of the systems is discussed based on the Parsec and Mist isochrones. The ages of the systems were established to be between 7.3-10.9 Gyr for OGLE-BLG-ECL-305487 and around 10 Gyr for OGLE-BLG-ECL-116218. We also measured the distances to the binaries. For OGLE-BLG-ECL-305487, d = 7.80 ± 0.18 (stat.) ± 0.19 (syst.) kpc and for OGLE-BLG-ECL-116218, d = 7.57 ± 0.28 (stat.) ± 0.19 (syst.) kpc.
The Messenger, 2020
1%. This is currently the best benchmark for cosmic distances and it will therefore impact severa... more 1%. This is currently the best benchmark for cosmic distances and it will therefore impact several fields of astrophysics. In particular, it has allowed a determination of the Hubble constant with a precision of 1.9%.
EAS Publications Series, 2013
We present distance determinations to the LMC and SMC based on very scarce long period eclipsing ... more We present distance determinations to the LMC and SMC based on very scarce long period eclipsing binary systems composed of giants. Our LMC distance accurate to 2.2 %, currently sets the best zero point for the whole extragalactic distance scale, while the 1 % relative distance between the LMC and SMC offers unique opportunity to study populational effects on the stellar distance indicators. We also present recent results on eclipsing binary systems containing classical Cepheids. They provide a way to precisely calibrate Baade-Wesselink technique for distance measurement. Apart from distances, analysis of our systems allowed us to measure with a very good accuracy basic stellar parameters (1-3 % radii, masses, effective temperature, etc) of relatively large sample of static giants (26) and also 5 classical Cepheids. This catalog provides unique opportunity to calibrate evolutionary models of giant stars and pulsating stars.
We present a new study of late-type eclipsing binary stars in the Small Magellanic Cloud (SMC) un... more We present a new study of late-type eclipsing binary stars in the Small Magellanic Cloud (SMC) undertaken with the aim of improving the distance determination to this important galaxy. A sample of 10 new detached, double-lined eclipsing binaries indentified from the OGLE variable star catalogues and consisting of F- and G-type giant components has been analysed. The absolute physical parameters of the individual components have been measured with a typical accuracy of better than 3%. All but one of the systems consist of young and intermediate population stars with masses in the range of 1.4 to 3.8 M_Sun. This new sample has been combined with five SMC eclipsing binaries previously published by our team. Distances to the binary systems were calculated using a surface brightness - color calibration. The targets form an elongated structure, highly inclined to the plane of the sky. The distance difference between the nearest and most-distant system amounts to 10 kpc with the line of si...
Using a sample of 81 galactic, detached eclipsing binary stars we investigated the global zero-po... more Using a sample of 81 galactic, detached eclipsing binary stars we investigated the global zero-point shift of their parallaxes with the Gaia Data Release 2 (DR2) parallaxes. The stars in the sample lay in a distance range of 0.04-2 kpc from the Sun. The photometric parallaxes π_Phot of the eclipsing binaries were determined by applying a number of empirical surface brightness - color (SBC) relations calibrated on optical-infrared colors. For each SBC relation we calculated the individual differences dπ_i = (π_Gaia - π_Phot)_i and then we calculated unweighted and weighted means. As the sample covers the whole sky we interpret the weighted means as the global shifts of the Gaia DR2 parallaxes with respect to our eclipsing binary sample. Depending on the choice of the SBC relation the shifts vary from -0.094 mas to -0.025 mas. The weighted mean of the zero-point shift from all colors and calibrations used is dπ = -0.054 +/- 0.024 mas. However, the SBC relations based on (B-K) and (V-K...
We present a distance determination to the Small Magellanic Cloud (SMC) based on an analysis of f... more We present a distance determination to the Small Magellanic Cloud (SMC) based on an analysis of four detached, long period, late type eclipsing binaries discovered by the OGLE Survey. The components of the binaries show negligible intrinsic variability. A consistent set of stellar parameters was derived with low statistical and systematic uncertainty. The absolute dimensions of the stars are calculated with a precision of better than 3%. The surface brightness-infrared color relation was used to derive the distance to each binary. The four systems clump around a distance modulus of (m − M) = 18.99 with a dispersion of only 0.05 mag. Combining these results with the distance published by Graczyk et al. for the eclipsing binary OGLE SMC113.3 4007 we obtain a mean distance modulus to the SMC of 18.965 ± 0.025 (stat.) ± 0.048 (syst.) mag. This corresponds to a distance of 62.1 ± 1.9 kpc, where the error includes both uncertainties. Taking into account other recent published determinations of the SMC distance we calculated the distance modulus difference between the SMC and the LMC equal to 0.458 ± 0.068 mag. Finally we advocate µ SMC = 18.95 ± 0.07 as a new "canonical" value of the distance modulus to this galaxy.
Motivated by an amazing range of reported distances to the nearby Local Group spiral galaxy M33, ... more Motivated by an amazing range of reported distances to the nearby Local Group spiral galaxy M33, we have obtained deep near-infrared photometry for 26 long-period Cepheids in this galaxy with the ESO VLT. From the data we constructed period-luminosity relations in the J and K bands which together with previous optical VI photometry for the Cepheids by Macri et al. were used to determine the true distance modulus of M33, and the mean reddening affecting the Cepheid sample with the multiwavelength fit method developed in the Araucaria Project. We find a true distance modulus of 24.62 for M33, with a total uncertainty of ± 0.07 mag which is dominated by the uncertainty on the photometric zero points in our photometry. The reddening is determined as E(B-V)=0.19 ± 0.02, in agreement with the value used by the HST Key Project of Freedman et al. but in some discrepancy with other recent determinations based on blue supergiant spectroscopy and an O-type eclipsing binary which yielded lower reddening values. Our derived M33 distance modulus is extremely insensitive to the adopted reddening law. We show that the possible effects of metallicity and crowding on our present distance determination are both at the 1-2% level and therefore minor contributors to the total uncertainty of our distance result for M33.
The Astrophysical Journal, 2021
Our work presents an independent calibration of the J-region Asymptotic Giant Branch (JAGB) metho... more Our work presents an independent calibration of the J-region Asymptotic Giant Branch (JAGB) method using Infrared Survey Facility photometric data and a custom luminosity function profile to determine JAGB mean magnitudes for nine galaxies. We determine a mean absolute magnitude of carbon stars of M LMC = −6.212 ± 0.010 (stat.) ±0.030 (syst.) mag. We then use near-infrared photometry of a number of nearby galaxies, originally obtained by our group to determine their distances from Cepheids using the Leavitt law, in order to independently determine their distances with the JAGB method. We compare the JAGB distances obtained in this work with the Cepheid distances resulting from the same photometry and find very good agreement between the results from the two methods. The mean difference is 0.01 mag with an rms scatter of 0.06 mag after taking into account seven out of the eight analyzed galaxies that had their distances determined using Cepheids. The very accurate distance to the Sma...
The Astrophysical Journal Supplement Series
Deep near-infrared J-and K-band photometry of three Local Group dwarf spheroidal galaxies: Fornax... more Deep near-infrared J-and K-band photometry of three Local Group dwarf spheroidal galaxies: Fornax, Carina, and Sculptor, is made available for the community. Until now, these data have only been used by the Araucaria Project to determine distances using the tip of the red giant and RR Lyrae stars. Now, we present the entire data collection in a form of a database, consisting of accurate Jand K-band magnitudes, sky coordinates, ellipticity measurements, and timestamps of observations, complemented by stars' loci in their reference images. Depth of our photometry reaches about 22 mag at 5σ level, and is comparable to NIR surveys, like the UKIRT Infrared Deep Sky Survey (UKIDSS) or the VISTA Hemisphere Survey (VHS). Small overlap with VHS and no overlap with UKIDSS makes our database a unique source of quality photometry.
The Astrophysical Journal
We present a new study of late-type eclipsing binary stars in the Small Magellanic Cloud (SMC) un... more We present a new study of late-type eclipsing binary stars in the Small Magellanic Cloud (SMC) undertaken with the aim of improving the distance determination to this important galaxy. A sample of 10 new detached, double-lined eclipsing binaries indentified from the OGLE variable star catalogues and consisting of F-and G-type giant components has been analysed. The absolute physical parameters of the individual components have been measured with a typical accuracy of better than 3%. All but one of the systems consist of young and intermediate population stars with masses in the range of 1.4 to 3.8 M. This new sample has been combined with five SMC eclipsing binaries previously published by our team. Distances to the binary systems were calculated using a surface brightness-color calibration. The targets form an elongated structure, highly inclined to the plane of the sky. The distance difference between the nearest and most-distant system amounts to 10 kpc with the line of sight depth reaching 7 kpc. We find tentative evidence of the existence of a spherical stellar sub-structure (core) in the SMC coinciding with its stellar center, containing about 40% of the young and intermediate age stars in the galaxy. The radial extension of this sub-structure is ∼ 1.5 kpc. We derive a distance to the SMC center of D SMC = 62.44 ± 0.47(stat.)±0.81 (syst.) kpc corresponding to a distance modulus (m − M) SMC = 18.977 ± 0.016 ± 0.028 mag, representing an accuracy of better than 2%.
The Astrophysical Journal
We present reddening maps of the Large Magellanic Cloud (LMC) and Small Magellanic Cloud (SMC), b... more We present reddening maps of the Large Magellanic Cloud (LMC) and Small Magellanic Cloud (SMC), based on color measurements of the red clump. Reddening values of our maps were obtained by calculating the difference of the observed and intrinsic color of the red clump in both galaxies. To obtain the intrinsic color of the red clump, we used reddenings obtained from late-type eclipsing binary systems, measurements for blue supergiants and reddenings derived from Strömgren photometry of B-type stars. We obtained intrinsic color of the red clump (V − I) 0 = 0.838 ± 0.034 mag in the LMC, and (V − I) 0 = 0.814 ± 0.034 mag in the SMC. We prepared our map with 3 arcmin resolution,
The Astrophysical Journal
Using a sample of 81 galactic, detached eclipsing binary stars we investigated the global zero-po... more Using a sample of 81 galactic, detached eclipsing binary stars we investigated the global zero-point shift of their parallaxes with the Gaia Data Release 2 (DR2) parallaxes. The stars in the sample lay in a distance range of 0.04-2 kpc from the Sun. The photometric parallaxes ϖ Phot of the eclipsing binaries were determined by applying a number of empirical surface brightness-color (SBC) relations calibrated on optical-infrared colors. For each SBC relation we calculated the individual differences v v v =-() d i G a i a i Phot and then we calculated unweighted and weighted means. As the sample covers the whole sky we interpret the weighted means as the global shifts of the Gaia DR2 parallaxes with respect to our eclipsing binary sample. Depending on the choice of the SBC relation the shifts vary from −0.094 to −0.025 mas. The weighted mean of the zero-point shift from all colors and calibrations used is dϖ=−0.054±0.024 mas. However, the SBC relations based on (B − K) and (V − K) colors, which are the least reddening dependent and have the lowest intrinsic dispersions, give a zero-point shift of dϖ=−0.031±0.011 mas in full agreement with results obtained by Lindegren et al. and Arenou et al. Our result confirms the global shift of Gaia DR2 parallaxes of dϖ=−0.029 mas reported by the Gaia team, but we do not confirm the larger zero-point shift reported by a number of follow-up papers.
The Astronomical Journal
We present new empirical calibrations of the absolute magnitude of the tip of the red giant branc... more We present new empirical calibrations of the absolute magnitude of the tip of the red giant branch (TRGB) in the optical I and near-infrared J, H, and K bands in terms of the (V-K) 0 , (V-H) 0 , and (J-K) 0 colors of the red giant branch. Our calibrations are based on the measurements in 19 fields in the Large and Small Magellanic Clouds, which span a wide (V-K) 0 color range of the brightest part of the red giant branch. We use a simple edge detection technique based on the comparison of the star count difference in two adjacent bins with the estimated Poisson noise. Further, we include the reddening and geometrical corrections, as well as the precise and accurate to 2% distance to the Large Magellanic Cloud. The calibration based on a (V-K) colors can be a robust tool to calculate with a great precision the absolute magnitude of the TRGB.
The Astrophysical Journal
We present a determination of precise fundamental physical parameters of twenty detached, doublel... more We present a determination of precise fundamental physical parameters of twenty detached, doublelined, eclipsing binary stars in the Large Magellanic Cloud (LMC) containing G-or early K-type giant stars. Eleven are new systems, the remaining nine are systems already analyzed by our team for which we present updated parameters. The catalogue results from our long-term survey of eclipsing binaries in the Magellanic Clouds suitable for high-precision determination of distances (the Araucaria project). The V-band brightnesses of the systems range from 15.4 mag to 17.7 mag and their orbital periods range from 49 days to 773 days. Six systems have favorable geometry showing total eclipses. The absolute dimensions of all eclipsing binary components are calculated with a precision of better than 3% and all systems are suitable for a precise distance determination. The measured stellar masses are in the range 1.4 to 4.6 M and comparison with the MESA isochrones gives ages between 0.1 and 2.1 Gyr. The systems show an age-metallicity relation with no evolution of metallicity for systems older than 0.6 Gy, followed by a rise to a metallicity maximum at age 0.5 Gy, and then a slow metallicity decrease until 0.1 Gy. Two systems have components with very different masses: OGLE LMC-ECL-05430 and OGLE LMC-ECL-18365. Neither system can be fitted by single stellar evolution isochrone, explained by a past mass transfer scenario in the case of ECL-18365 and a gravitational capture or a hierarchical binary merger scenario in the case of ECL-05430. The longest period system OGLE LMC SC9 230659 shows a surprising apsidal motion which shifts the apparent position of the eclipses. This is a clear sign of a physical companion to the system, however neither investigation of the spectra nor light curve analysis indicate a third light contribution larger than 2-3%. In one spectrum of OGLE LMC-ECL-12669 we noted a peculiar dimming of one of the components by 65% well outside of the eclipses. We interpret this observation as arising from an extremely rare occultation event as a foreground Galactic object covers only one component of an extragalactic eclipsing binary.
The Astronomical Journal, 2016
The Astrophysical Journal, 2015
This research is based on observations obtained with the ESO VLT, 3.6 m and NTT telescopes for Pr... more This research is based on observations obtained with the ESO VLT, 3.6 m and NTT telescopes for Programmes 092.D-0295(A), 091.D-0393(A), 089.D-0330(A), 088.D-0447(A), 086.D-0103(A) and 085.D-0398(A)), and with the Magellan Clay and Warsaw telescopes at Las Campanas Observatory.
EPJ Web of Conferences, 2015
The Astronomical Journal, 2015
We obtained single-phase near-infrared (NIR) magnitudes in the J-and K-band for a sample of 33 RR... more We obtained single-phase near-infrared (NIR) magnitudes in the J-and K-band for a sample of 33 RR Lyrae stars in the Carina dSph galaxy. Applying different theoretical and empirical calibrations of the NIR period-luminosity-metallicity relation for RR Lyrae stars, we find consistent results and obtain a true, reddening-corrected distance modulus of 20.118 ± 0.017 (statistical) ± 0.11 (systematic) mag. This value is in excellent agreement with the results obtained in the context of the Araucaria project from NIR photometry of Red Clump stars (20.165 ± 0.015) and Tip of Red Giant Branch (20.09 ± 0.03 ± 0.12 mag in J-band, 20.14 ± 0.04 ± 0.14 mag in K-band), as well as with most independent distance determinations to this galaxy. The near-infrared RRL method proved to be a reliable tool for accurate distance determination at the 5 percent level or better, particularly for galaxies and globular clusters that lack young standard candles, like Cepheids.
The Astronomical Journal, 2009
We have obtained deep infrared J and K band observations of nine 4.9 × 4.9 arcmin fields in the S... more We have obtained deep infrared J and K band observations of nine 4.9 × 4.9 arcmin fields in the Small Magellanic Cloud (SMC) with the ESO New Technology Telescope equipped with the SOFI infrared camera. In these fields, 34 RR Lyrae stars catalogued by the OGLE collaboration were identified. Using different theoretical and empirical calibrations of the infrared period-luminositymetallicity relation, we find consistent SMC distance moduli, and find a best true distance modulus to the SMC of 18.97 ± 0.03 (statistical) ± 0.12 (systematic) mag which agrees well with most independent distance determinations to this galaxy, and puts the SMC 0.39 mag more distant than the LMC for which our group has recently derived, from the same technique, a distance of 18.58 mag.
Astronomy & Astrophysics
Aims. Our goal is to determine, with high accuracy, the physical and orbital parameters of two do... more Aims. 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 aim to study the evolutionary status of the binaries, to derive the distances towards them by using a surface brightness-colour relation, and to compare these measurements with the measurements presented by the Gaia mission. Methods. In order to measure the physical and orbital parameters of the systems, we analysed the light curves and radial-velocity curves with the Wilson-Devinney code. We used V-band and I-band photometry from the Optical Gravitational Lensing Experiment (OGLE) catalogue and near-infrared photometry obtained with the New Technology Telescope (NTT) equipped with the SOFI instrument. The spectroscopic data were collected with the High Accuracy Radial velocity Planet Searcher (HARPS) spectrograph mounted at the ESO 3.6-m telescope and the Magellan Inamori Kyocera Echelle (MIKE) spectrograph mounted at the 6.5-m Clay telescope. Results. We present the first analysis of this kind for two evolved eclipsing binary systems from the OGLE catalogue: OGLE-BLG-ECL-305487 and OGLE-BLG-ECL-116218. The masses of the components of OGLE-BLG-ECL-305487 are M 1 = 1.059 ± 0.019 and M 2 = 0.991 ± 0.018 M , and the radii are R 1 = 19.27 ± 0.28 and R 2 = 29.99 ± 0.24 R. For OGLE-BLG-ECL-116218, the masses are M 1 = 0.969 ± 0.012 and M 2 = 0.983 ± 0.012 M , while the radii are R 1 = 16.73 ± 0.28 and R 2 = 22.06 ± 0.26 R. The evolutionary status of the systems is discussed based on the Parsec and Mist isochrones. The ages of the systems were established to be between 7.3-10.9 Gyr for OGLE-BLG-ECL-305487 and around 10 Gyr for OGLE-BLG-ECL-116218. We also measured the distances to the binaries. For OGLE-BLG-ECL-305487, d = 7.80 ± 0.18 (stat.) ± 0.19 (syst.) kpc and for OGLE-BLG-ECL-116218, d = 7.57 ± 0.28 (stat.) ± 0.19 (syst.) kpc.
The Messenger, 2020
1%. This is currently the best benchmark for cosmic distances and it will therefore impact severa... more 1%. This is currently the best benchmark for cosmic distances and it will therefore impact several fields of astrophysics. In particular, it has allowed a determination of the Hubble constant with a precision of 1.9%.
EAS Publications Series, 2013
We present distance determinations to the LMC and SMC based on very scarce long period eclipsing ... more We present distance determinations to the LMC and SMC based on very scarce long period eclipsing binary systems composed of giants. Our LMC distance accurate to 2.2 %, currently sets the best zero point for the whole extragalactic distance scale, while the 1 % relative distance between the LMC and SMC offers unique opportunity to study populational effects on the stellar distance indicators. We also present recent results on eclipsing binary systems containing classical Cepheids. They provide a way to precisely calibrate Baade-Wesselink technique for distance measurement. Apart from distances, analysis of our systems allowed us to measure with a very good accuracy basic stellar parameters (1-3 % radii, masses, effective temperature, etc) of relatively large sample of static giants (26) and also 5 classical Cepheids. This catalog provides unique opportunity to calibrate evolutionary models of giant stars and pulsating stars.
We present a new study of late-type eclipsing binary stars in the Small Magellanic Cloud (SMC) un... more We present a new study of late-type eclipsing binary stars in the Small Magellanic Cloud (SMC) undertaken with the aim of improving the distance determination to this important galaxy. A sample of 10 new detached, double-lined eclipsing binaries indentified from the OGLE variable star catalogues and consisting of F- and G-type giant components has been analysed. The absolute physical parameters of the individual components have been measured with a typical accuracy of better than 3%. All but one of the systems consist of young and intermediate population stars with masses in the range of 1.4 to 3.8 M_Sun. This new sample has been combined with five SMC eclipsing binaries previously published by our team. Distances to the binary systems were calculated using a surface brightness - color calibration. The targets form an elongated structure, highly inclined to the plane of the sky. The distance difference between the nearest and most-distant system amounts to 10 kpc with the line of si...
Using a sample of 81 galactic, detached eclipsing binary stars we investigated the global zero-po... more Using a sample of 81 galactic, detached eclipsing binary stars we investigated the global zero-point shift of their parallaxes with the Gaia Data Release 2 (DR2) parallaxes. The stars in the sample lay in a distance range of 0.04-2 kpc from the Sun. The photometric parallaxes π_Phot of the eclipsing binaries were determined by applying a number of empirical surface brightness - color (SBC) relations calibrated on optical-infrared colors. For each SBC relation we calculated the individual differences dπ_i = (π_Gaia - π_Phot)_i and then we calculated unweighted and weighted means. As the sample covers the whole sky we interpret the weighted means as the global shifts of the Gaia DR2 parallaxes with respect to our eclipsing binary sample. Depending on the choice of the SBC relation the shifts vary from -0.094 mas to -0.025 mas. The weighted mean of the zero-point shift from all colors and calibrations used is dπ = -0.054 +/- 0.024 mas. However, the SBC relations based on (B-K) and (V-K...
We present a distance determination to the Small Magellanic Cloud (SMC) based on an analysis of f... more We present a distance determination to the Small Magellanic Cloud (SMC) based on an analysis of four detached, long period, late type eclipsing binaries discovered by the OGLE Survey. The components of the binaries show negligible intrinsic variability. A consistent set of stellar parameters was derived with low statistical and systematic uncertainty. The absolute dimensions of the stars are calculated with a precision of better than 3%. The surface brightness-infrared color relation was used to derive the distance to each binary. The four systems clump around a distance modulus of (m − M) = 18.99 with a dispersion of only 0.05 mag. Combining these results with the distance published by Graczyk et al. for the eclipsing binary OGLE SMC113.3 4007 we obtain a mean distance modulus to the SMC of 18.965 ± 0.025 (stat.) ± 0.048 (syst.) mag. This corresponds to a distance of 62.1 ± 1.9 kpc, where the error includes both uncertainties. Taking into account other recent published determinations of the SMC distance we calculated the distance modulus difference between the SMC and the LMC equal to 0.458 ± 0.068 mag. Finally we advocate µ SMC = 18.95 ± 0.07 as a new "canonical" value of the distance modulus to this galaxy.
Motivated by an amazing range of reported distances to the nearby Local Group spiral galaxy M33, ... more Motivated by an amazing range of reported distances to the nearby Local Group spiral galaxy M33, we have obtained deep near-infrared photometry for 26 long-period Cepheids in this galaxy with the ESO VLT. From the data we constructed period-luminosity relations in the J and K bands which together with previous optical VI photometry for the Cepheids by Macri et al. were used to determine the true distance modulus of M33, and the mean reddening affecting the Cepheid sample with the multiwavelength fit method developed in the Araucaria Project. We find a true distance modulus of 24.62 for M33, with a total uncertainty of ± 0.07 mag which is dominated by the uncertainty on the photometric zero points in our photometry. The reddening is determined as E(B-V)=0.19 ± 0.02, in agreement with the value used by the HST Key Project of Freedman et al. but in some discrepancy with other recent determinations based on blue supergiant spectroscopy and an O-type eclipsing binary which yielded lower reddening values. Our derived M33 distance modulus is extremely insensitive to the adopted reddening law. We show that the possible effects of metallicity and crowding on our present distance determination are both at the 1-2% level and therefore minor contributors to the total uncertainty of our distance result for M33.
The Astrophysical Journal, 2021
Our work presents an independent calibration of the J-region Asymptotic Giant Branch (JAGB) metho... more Our work presents an independent calibration of the J-region Asymptotic Giant Branch (JAGB) method using Infrared Survey Facility photometric data and a custom luminosity function profile to determine JAGB mean magnitudes for nine galaxies. We determine a mean absolute magnitude of carbon stars of M LMC = −6.212 ± 0.010 (stat.) ±0.030 (syst.) mag. We then use near-infrared photometry of a number of nearby galaxies, originally obtained by our group to determine their distances from Cepheids using the Leavitt law, in order to independently determine their distances with the JAGB method. We compare the JAGB distances obtained in this work with the Cepheid distances resulting from the same photometry and find very good agreement between the results from the two methods. The mean difference is 0.01 mag with an rms scatter of 0.06 mag after taking into account seven out of the eight analyzed galaxies that had their distances determined using Cepheids. The very accurate distance to the Sma...
The Astrophysical Journal Supplement Series
Deep near-infrared J-and K-band photometry of three Local Group dwarf spheroidal galaxies: Fornax... more Deep near-infrared J-and K-band photometry of three Local Group dwarf spheroidal galaxies: Fornax, Carina, and Sculptor, is made available for the community. Until now, these data have only been used by the Araucaria Project to determine distances using the tip of the red giant and RR Lyrae stars. Now, we present the entire data collection in a form of a database, consisting of accurate Jand K-band magnitudes, sky coordinates, ellipticity measurements, and timestamps of observations, complemented by stars' loci in their reference images. Depth of our photometry reaches about 22 mag at 5σ level, and is comparable to NIR surveys, like the UKIRT Infrared Deep Sky Survey (UKIDSS) or the VISTA Hemisphere Survey (VHS). Small overlap with VHS and no overlap with UKIDSS makes our database a unique source of quality photometry.
The Astrophysical Journal
We present a new study of late-type eclipsing binary stars in the Small Magellanic Cloud (SMC) un... more We present a new study of late-type eclipsing binary stars in the Small Magellanic Cloud (SMC) undertaken with the aim of improving the distance determination to this important galaxy. A sample of 10 new detached, double-lined eclipsing binaries indentified from the OGLE variable star catalogues and consisting of F-and G-type giant components has been analysed. The absolute physical parameters of the individual components have been measured with a typical accuracy of better than 3%. All but one of the systems consist of young and intermediate population stars with masses in the range of 1.4 to 3.8 M. This new sample has been combined with five SMC eclipsing binaries previously published by our team. Distances to the binary systems were calculated using a surface brightness-color calibration. The targets form an elongated structure, highly inclined to the plane of the sky. The distance difference between the nearest and most-distant system amounts to 10 kpc with the line of sight depth reaching 7 kpc. We find tentative evidence of the existence of a spherical stellar sub-structure (core) in the SMC coinciding with its stellar center, containing about 40% of the young and intermediate age stars in the galaxy. The radial extension of this sub-structure is ∼ 1.5 kpc. We derive a distance to the SMC center of D SMC = 62.44 ± 0.47(stat.)±0.81 (syst.) kpc corresponding to a distance modulus (m − M) SMC = 18.977 ± 0.016 ± 0.028 mag, representing an accuracy of better than 2%.
The Astrophysical Journal
We present reddening maps of the Large Magellanic Cloud (LMC) and Small Magellanic Cloud (SMC), b... more We present reddening maps of the Large Magellanic Cloud (LMC) and Small Magellanic Cloud (SMC), based on color measurements of the red clump. Reddening values of our maps were obtained by calculating the difference of the observed and intrinsic color of the red clump in both galaxies. To obtain the intrinsic color of the red clump, we used reddenings obtained from late-type eclipsing binary systems, measurements for blue supergiants and reddenings derived from Strömgren photometry of B-type stars. We obtained intrinsic color of the red clump (V − I) 0 = 0.838 ± 0.034 mag in the LMC, and (V − I) 0 = 0.814 ± 0.034 mag in the SMC. We prepared our map with 3 arcmin resolution,
The Astrophysical Journal
Using a sample of 81 galactic, detached eclipsing binary stars we investigated the global zero-po... more Using a sample of 81 galactic, detached eclipsing binary stars we investigated the global zero-point shift of their parallaxes with the Gaia Data Release 2 (DR2) parallaxes. The stars in the sample lay in a distance range of 0.04-2 kpc from the Sun. The photometric parallaxes ϖ Phot of the eclipsing binaries were determined by applying a number of empirical surface brightness-color (SBC) relations calibrated on optical-infrared colors. For each SBC relation we calculated the individual differences v v v =-() d i G a i a i Phot and then we calculated unweighted and weighted means. As the sample covers the whole sky we interpret the weighted means as the global shifts of the Gaia DR2 parallaxes with respect to our eclipsing binary sample. Depending on the choice of the SBC relation the shifts vary from −0.094 to −0.025 mas. The weighted mean of the zero-point shift from all colors and calibrations used is dϖ=−0.054±0.024 mas. However, the SBC relations based on (B − K) and (V − K) colors, which are the least reddening dependent and have the lowest intrinsic dispersions, give a zero-point shift of dϖ=−0.031±0.011 mas in full agreement with results obtained by Lindegren et al. and Arenou et al. Our result confirms the global shift of Gaia DR2 parallaxes of dϖ=−0.029 mas reported by the Gaia team, but we do not confirm the larger zero-point shift reported by a number of follow-up papers.
The Astronomical Journal
We present new empirical calibrations of the absolute magnitude of the tip of the red giant branc... more We present new empirical calibrations of the absolute magnitude of the tip of the red giant branch (TRGB) in the optical I and near-infrared J, H, and K bands in terms of the (V-K) 0 , (V-H) 0 , and (J-K) 0 colors of the red giant branch. Our calibrations are based on the measurements in 19 fields in the Large and Small Magellanic Clouds, which span a wide (V-K) 0 color range of the brightest part of the red giant branch. We use a simple edge detection technique based on the comparison of the star count difference in two adjacent bins with the estimated Poisson noise. Further, we include the reddening and geometrical corrections, as well as the precise and accurate to 2% distance to the Large Magellanic Cloud. The calibration based on a (V-K) colors can be a robust tool to calculate with a great precision the absolute magnitude of the TRGB.
The Astrophysical Journal
We present a determination of precise fundamental physical parameters of twenty detached, doublel... more We present a determination of precise fundamental physical parameters of twenty detached, doublelined, eclipsing binary stars in the Large Magellanic Cloud (LMC) containing G-or early K-type giant stars. Eleven are new systems, the remaining nine are systems already analyzed by our team for which we present updated parameters. The catalogue results from our long-term survey of eclipsing binaries in the Magellanic Clouds suitable for high-precision determination of distances (the Araucaria project). The V-band brightnesses of the systems range from 15.4 mag to 17.7 mag and their orbital periods range from 49 days to 773 days. Six systems have favorable geometry showing total eclipses. The absolute dimensions of all eclipsing binary components are calculated with a precision of better than 3% and all systems are suitable for a precise distance determination. The measured stellar masses are in the range 1.4 to 4.6 M and comparison with the MESA isochrones gives ages between 0.1 and 2.1 Gyr. The systems show an age-metallicity relation with no evolution of metallicity for systems older than 0.6 Gy, followed by a rise to a metallicity maximum at age 0.5 Gy, and then a slow metallicity decrease until 0.1 Gy. Two systems have components with very different masses: OGLE LMC-ECL-05430 and OGLE LMC-ECL-18365. Neither system can be fitted by single stellar evolution isochrone, explained by a past mass transfer scenario in the case of ECL-18365 and a gravitational capture or a hierarchical binary merger scenario in the case of ECL-05430. The longest period system OGLE LMC SC9 230659 shows a surprising apsidal motion which shifts the apparent position of the eclipses. This is a clear sign of a physical companion to the system, however neither investigation of the spectra nor light curve analysis indicate a third light contribution larger than 2-3%. In one spectrum of OGLE LMC-ECL-12669 we noted a peculiar dimming of one of the components by 65% well outside of the eclipses. We interpret this observation as arising from an extremely rare occultation event as a foreground Galactic object covers only one component of an extragalactic eclipsing binary.
The Astronomical Journal, 2016
The Astrophysical Journal, 2015
This research is based on observations obtained with the ESO VLT, 3.6 m and NTT telescopes for Pr... more This research is based on observations obtained with the ESO VLT, 3.6 m and NTT telescopes for Programmes 092.D-0295(A), 091.D-0393(A), 089.D-0330(A), 088.D-0447(A), 086.D-0103(A) and 085.D-0398(A)), and with the Magellan Clay and Warsaw telescopes at Las Campanas Observatory.
EPJ Web of Conferences, 2015
The Astronomical Journal, 2015
We obtained single-phase near-infrared (NIR) magnitudes in the J-and K-band for a sample of 33 RR... more We obtained single-phase near-infrared (NIR) magnitudes in the J-and K-band for a sample of 33 RR Lyrae stars in the Carina dSph galaxy. Applying different theoretical and empirical calibrations of the NIR period-luminosity-metallicity relation for RR Lyrae stars, we find consistent results and obtain a true, reddening-corrected distance modulus of 20.118 ± 0.017 (statistical) ± 0.11 (systematic) mag. This value is in excellent agreement with the results obtained in the context of the Araucaria project from NIR photometry of Red Clump stars (20.165 ± 0.015) and Tip of Red Giant Branch (20.09 ± 0.03 ± 0.12 mag in J-band, 20.14 ± 0.04 ± 0.14 mag in K-band), as well as with most independent distance determinations to this galaxy. The near-infrared RRL method proved to be a reliable tool for accurate distance determination at the 5 percent level or better, particularly for galaxies and globular clusters that lack young standard candles, like Cepheids.
The Astronomical Journal, 2009
We have obtained deep infrared J and K band observations of nine 4.9 × 4.9 arcmin fields in the S... more We have obtained deep infrared J and K band observations of nine 4.9 × 4.9 arcmin fields in the Small Magellanic Cloud (SMC) with the ESO New Technology Telescope equipped with the SOFI infrared camera. In these fields, 34 RR Lyrae stars catalogued by the OGLE collaboration were identified. Using different theoretical and empirical calibrations of the infrared period-luminositymetallicity relation, we find consistent SMC distance moduli, and find a best true distance modulus to the SMC of 18.97 ± 0.03 (statistical) ± 0.12 (systematic) mag which agrees well with most independent distance determinations to this galaxy, and puts the SMC 0.39 mag more distant than the LMC for which our group has recently derived, from the same technique, a distance of 18.58 mag.