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1831. OGLE-III, MCPS and HST VI obs. of LMC & SMC
ID:
ivo://CDS.VizieR/J/ApJ/886/61
Title:
OGLE-III, MCPS and HST VI obs. of LMC & SMC
Short Name:
J/ApJ/886/61
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a calibration of the tip of the red giant branch (TRGB) in the Large Magellanic Cloud (LMC) on the Hubble Space Telescope (HST)/ACS F814W system. We use archival HST observations to derive blending corrections and photometric transformations for two ground-based wide-area imaging surveys of the Magellanic Clouds. We show that these surveys are biased bright by up to ~0.1mag in the optical due to blending, and that the bias is a function of local stellar density. We correct the LMC TRGB magnitudes from Jang & Lee (2017ApJ...835...28J) and use the geometric distance from Pietrzynski+ (2019Natur.567..200P) to obtain an absolute TRGB magnitude of M_F814W_=-3.97+/-0.046mag. Applying this calibration to the TRGB magnitudes from Freedman+ (2019ApJ...882...34F) in SN Ia hosts yields a value for the Hubble constant of H_0_=72.4+/-2.0km/s/Mpc for their TRGB+SNe Ia distance ladder. The difference in the TRGB calibration and the value of H_0_ derived here and by Freedman+ primarily results from their overestimate of the LMC extinction, caused by inconsistencies in their different sources of TRGB photometry for the Magellanic Clouds. Using the same source of photometry (OGLE) for both Clouds and applying the aforementioned corrections yields a value for the LMC I-band TRGB extinction that is lower by 0.06mag, consistent with independent OGLE reddening maps used by us and by Jang & Lee to calibrate TRGB and determine H0.
1832. OGLE-III Mira variables in the Magellanic Clouds
ID:
ivo://CDS.VizieR/J/ApJ/884/20
Title:
OGLE-III Mira variables in the Magellanic Clouds
Short Name:
J/ApJ/884/20
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present Period-Luminosity and Period-Luminosity-Color relations at maximum light for Mira variables in the Magellanic Clouds using time-series data from the Optical Gravitational Lensing Experiment (OGLE-III) and Gaia data release 2. The maximum-light relations exhibit a scatter typically up to ~30% smaller than their mean-light counterparts. The apparent magnitudes of oxygen-rich Miras at maximum light display significantly smaller cycle-to-cycle variations than at minimum light. High-precision photometric data for Kepler Mira candidates also exhibit stable magnitude variations at the brightest epochs, while their multi-epoch spectra display strong Balmer emission lines and weak molecular absorption at maximum light. The stability of maximum-light magnitudes for Miras possibly occurs due to the decrease in the sensitivity to molecular bands at their warmest phase. At near-infrared wavelengths, the period-luminosity relations (PLRs) of Miras display similar dispersion at mean and maximum light with limited time-series data in the Magellanic Clouds. A kink in the oxygen-rich Mira PLRs is found at 300 days in the VI-bands, which shifts to longer periods (~350 days) at near-infrared wavelengths. Oxygen-rich Mira PLRs at maximum light provide a relative distance modulus, {Delta}{mu}=0.48+/-0.08mag, between the Magellanic Clouds with a smaller statistical uncertainty than the mean-light relations. The maximum-light properties of Miras can be very useful for stellar atmosphere modeling and distance scale studies provided their stability and the universality can be established in other stellar environments in the era of extremely large telescopes.
1833. OGLE-III variable stars in Galactic disk area
ID:
ivo://CDS.VizieR/J/AcA/63/379
Title:
OGLE-III variable stars in Galactic disk area
Short Name:
J/AcA/63/379
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results of a search for pulsating stars in the 7.12deg^2^ OGLE-III Galactic disk area in the direction tangent to the Centaurus Arm. We report the identification of 20 Classical Cepheids, 45 RR Lyr type stars, 31 Long-Period Variables, such as Miras and Semi-Regular Variables, one pulsating white dwarf, and 58 very likely {delta} Sct type stars. Based on asteroseismic models constructed for one quadruple-mode and six triple-mode {delta} Sct type pulsators, we estimated masses, metallicities, ages, and distance moduli to these objects. The modeled stars have masses in the range 0.9-2.5M_{sun}_ and are located at distances between 2.5kpc and 6.2kpc. Two triple-mode and one double-mode pulsators seem to be Population II stars of the SX Phe type, probably from the Galactic halo. Our sample also includes candidates for Type II Cepheids and unclassified short-period (P<0.23d) multi-mode stars which could be either {delta}Sct or {beta}Cep type stars. One of the detected variables is a very likely {delta} Sct star with an exceptionally high peak-to-peak I-band amplitude of 0.35mag at the very short period of 0.0196d. All reported pulsating variable stars but one object are new discoveries. They are included in the OGLE-III Catalog of Variable Stars. Finally, we introduce the on-going OGLE-IV Galactic Disk Survey, which covers more than half of the Galactic plane. For the purposes of future works on the spiral structure and star formation history of the Milky Way, we have already compiled a list of known Galactic Classical Cepheids.
1834. OGLE-I long-period and non-periodic variables
ID:
ivo://CDS.VizieR/J/AcA/48/289
Title:
OGLE-I long-period and non-periodic variables
Short Name:
J/AcA/48/289
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a list of long-period and non-periodic variable stars detected in the OGLE-I database. These stars were not included in previous catalogs of periodic stars found in OGLE data. The catalog contains 116 stars in twelve Baade's Window fields and additionally in the Galactic bulge fields: MM1/5/7-A/B, MM3 and GB1.
1835. OGLE LMC BVI photometry
ID:
ivo://CDS.VizieR/J/AcA/50/307
Title:
OGLE LMC BVI photometry
Short Name:
J/AcA/50/307
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the BVI photometric maps of the Large Magellanic Cloud. They contain BVI photometry and astrometry of more than 7 million stars from the central parts of the LMC. The data were collected during the second phase of the OGLE microlensing project. We discuss the accuracy of the data and present color-magnitude diagrams of all 26 fields observed by OGLE in the LMC. The BVI maps of the LMC are accessible electronically for the astronomical community from the OGLE Internet archive.
1836. OGLE RR Lyrae in LMC
ID:
ivo://CDS.VizieR/J/AcA/53/93
Title:
OGLE RR Lyrae in LMC
Short Name:
J/AcA/53/93
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the catalog of RR Lyr stars discovered in a 4.5 square degrees area in the central parts of the Large Magellanic Cloud (LMC). Presented sample contains 7612 objects, including 5455 fundamental mode pulsators (RRab), 1655 first-overtone (RRc), 272 second-overtone (RRe) and 230 double-mode RR Lyr stars (RRd). Additionally we attach alist of several dozen other short-period pulsating variables. The catalog data include astrometry, periods, BVI photometry, amplitudes, and parameters of the Fourier decomposition of the I-band light curve of each object. We provide a list of six LMC star clusters which contain RR Lyr stars. The richest cluster, NGC 1835, hosts 84 RR Lyr variables. The period distribution of these stars suggests that NGC1835 shares features of Oosterhoff type I and type II groups. All presented data, including individual BVI observations and finding charts are available from the OGLE Internet archive at ftp://sirius.astrouw.edu.pl/ogle/ogle2/var_stars/lmc/rrlyr
1837. OGLE RR Lyrae VI photometry
ID:
ivo://CDS.VizieR/J/AcA/48/113
Title:
OGLE RR Lyrae VI photometry
Short Name:
J/AcA/48/113
Date:
21 Oct 2021
Publisher:
CDS
Description:
We analyze the mean luminosity of three samples of field RRab Lyr stars observed in the course of the OGLE microlensing experiment: 73 stars from the Galactic bulge and 110 and 128 stars from selected fields in the LMC and SMC, respectively. The fields are the same as in the recent distance determination to the Magellanic Clouds with the red clump stars method by Udalski et al. (1998AcA....48....1U). We determine the relative distance scale Galactic Bulge: 0.194+/-0.010; LMC: 1.00 ; SMC: 1.30+/-0.08. We calibrate our RR Lyr distance scale with the recent calibration of Gould and Popowski (1998ApJ...508..844G) based on statistical parallaxes. We obtain the following distance moduli to the Galactic bulge, LMC and SMC: m-M=14.5+/-0.15, m-M=18.09+/-0.16 and m-M=18.66+/-0.16mag.
1838. OGLE SMC BVI photometry
ID:
ivo://CDS.VizieR/J/AcA/48/147
Title:
OGLE SMC BVI photometry
Short Name:
J/AcA/48/147
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present three color, BVI maps of the Small Magellanic Cloud. The maps contain precise photometric and astrometric data for about 2.2million stars from the central regions of the SMC bar covering ~2.4 square degrees on the sky. Mean brightness of stars is derived from observations collected in the course of the OGLE-II microlensing search from about 130, 30 and 15 measurements in the I, V and B-bands, respectively. Accuracy of the zero points of photometry is about 0.01mag, and astrometry 0.15arcsec (with possible systematic error up to 0.7arcsec). Color magnitude diagrams of observed fields are also presented. The maps of the SMC are the first from the series of similar maps covering other OGLE fields: LMC, Galactic bulge and Galactic disk. The data are very well suited for many projects, particularly for the SMC which has been neglected photometrically for years.
1839. OGLE SMC clusters
ID:
ivo://CDS.VizieR/J/AcA/48/175
Title:
OGLE SMC clusters
Short Name:
J/AcA/48/175
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the catalog of clusters found in the area of ~2.4 square degrees in the central region of the Small Magellanic Cloud. The catalog contains data for 238 clusters, 72 of them are new objects. For each cluster equatorial coordinates, radii, approximate number of members, cross-identification, finding chart and color magnitude diagrams: V-(B-V) and V-(V-I) are provided.
1840. OGLE UBVI phot. in Baade's Window
ID:
ivo://CDS.VizieR/J/AcA/49/319
Title:
OGLE UBVI phot. in Baade's Window
Short Name:
J/AcA/49/319
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present UBVI photometry for 8530 stars in Baade's Window obtained during the OGLE-II microlensing survey. Among these are over one thousand red clump giants. 1391 of them have photometry with errors smaller than 0.04, 0.06, 0.12, and 0.20 mag in the I, V, B, and U-band, respectively. We constructed a map of interstellar reddening. The corrected colors of the red clump giants: (U-B)_0_, (B-V)_0_, and (V-I)_0_ are very well correlated, indicating that a single parameter determines the observed spread of their values, reaching almost 2mag in the (U-B)_0_. It seems most likely that heavy element content is the dominant parameter, but it is possible that another parameter: the age (or mass) of a star moves it along the same trajectory in the color-color diagram as the metallicity. The current ambiguity can be resolved with spectral analysis, and our catalog may be useful as a finding list of red clump giants. We point out that these K giants are more suitable for a fair determination of the distribution of metallicity than brighter M giants. We also present a compilation of UBVI data for 308 red clump giants near the Sun, for which Hipparcos parallaxes are more accurate than 10%. Spectral analysis of their metallicity may provide information about the local metallicity distribution as well as the extent to which mass (age) of these stars affects their colors.