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4661. 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.
4662. OGLE variables in Galactic bar
ID:
ivo://CDS.VizieR/J/MNRAS/349/1059
Title:
OGLE variables in Galactic bar
Short Name:
J/MNRAS/349/1059
Date:
21 Oct 2021
Publisher:
CDS
Description:
Among over 200000 Galactic bulge variable stars in the public domain Optical Gravitational Lensing Experiment (OGLE) catalogue, we found over 15000 red giant variables following two well-defined period-amplitude relations. The periods are in the range 10<P<100d, and amplitudes in the range 0.005<A<0.13mag in the I band. The variables cover a broad range of reddening-corrected colours, 1<(V-I)_0_<5, and a fairly narrow range of extinction-corrected apparent magnitudes, 10.5<I_0_<13. A subset of variables (type A) has an rms scatter of only 0.44mag. The average magnitudes for these stars are well correlated with the Galactic longitude, and vary from I_k,0_=11.82 for l=+8{deg} to I_k,0_=12.07 for l=-5{deg}, clearly indicating that they are located in the Galactic bar. Most variables have several oscillation periods.
4663. OGLE Variables in Magellanic Clouds
ID:
ivo://CDS.VizieR/J/MNRAS/353/705
Title:
OGLE Variables in Magellanic Clouds
Short Name:
J/MNRAS/353/705
Date:
21 Oct 2021
Publisher:
CDS
Description:
The data of 8852 and 2927 variable stars detected by the OGLE survey in the Large and Small Magellanic Clouds are presented. They are cross-identified with the SIRIUS JHK survey data, and their infrared properties are discussed. Variable red giants are well separated on the period-(J-K) plane, suggesting that it could be a good tool to distinguish their pulsation mode and type.
4664. OH/IR stars photometry
ID:
ivo://CDS.VizieR/J/A+A/299/453
Title:
OH/IR stars photometry
Short Name:
J/A+A/299/453
Date:
21 Oct 2021
Publisher:
CDS
Description:
This paper presents JHKL'M photometry of a new sample of OH/IR stars. These data are merged with similar observations collected in the literature in order to constitute a data base of near-infrared photometry for 400 OH/IR stars. After removing from this sample the objects that are unlikely to be AGB stars, we obtain a sequence of average OH/IR stars with increasing values of the colour index K-L'. A simple model of a star surrounded by a circumstellar shell is constructed in order to derive basic parameters such as luminosity, radius, stellar temperature, optical depth of the dust shell and mass loss rate. These parameters are found to vary smoothly along the sequence of OH/IR stars, and the K-L' colour is shown to describe almost completely the basic physical parameters of an OH/IR star. The metallicity affects the OH-peak separation, but does not play an important role in the definition of the other properties.
4665. OH megamasers infrared photometry
ID:
ivo://CDS.VizieR/J/AJ/133/496
Title:
OH megamasers infrared photometry
Short Name:
J/AJ/133/496
Date:
21 Oct 2021
Publisher:
CDS
Description:
OH megamasers are the most luminous masers in the universe. The total of 109 OH megamaser (OHM) galaxies known so far have been collected, and cross-identifications of those OHM galaxies with Two Micron All Sky Survey (2MASS) sources are made in this paper. Using 2MASS (Cat. II/246) and IRAS (Cat. II/125, II/156) data, the infrared properties of OHM-detected and non-detected sources are compared.
4666. [OII] emitting galaxies in COSMOS & SDF fields
ID:
ivo://CDS.VizieR/J/ApJS/172/456
Title:
[OII] emitting galaxies in COSMOS & SDF fields
Short Name:
J/ApJS/172/456
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have carried out a wide-field imaging survey for [OII] {lambda}3727 emitting galaxies at z~1.2 in the HST COSMOS 2 square degree field using the Suprime-Cam on the Subaru Telescope. The survey covers a sky area of 6700arcmin^2^ in the COSMOS field, and a redshift range between 1.17 and 1.20 ({Delta}z=0.03), corresponding to a survey volume of 5.56x10^5^Mpc^3^. We obtain a sample of 3176 [OII] emitting galaxies with observed emission-line equivalent widths greater than 26{AA}. Since our survey tends to sample brighter [OII] emitting galaxies, we also analyze a sample of fainter [OII] emitting galaxies found in the Subaru Deep Field (SDF). We find an extinction-corrected [OII] luminosity density of 10Exp(40.35^+0.08^_-0.06_)^erg/s/Mpc^3^, corresponding to star formation rate density of 0.32^+0.06^_-0.04_ M_{sun}_/yr/Mpc^3^ in the COSMOS field at z~1.2. This is the largest survey for [OII] emitters beyond z=1 currently available.
4667. OJ 287 far-infrared photometry
ID:
ivo://CDS.VizieR/J/A+A/610/A74
Title:
OJ 287 far-infrared photometry
Short Name:
J/A+A/610/A74
Date:
21 Oct 2021
Publisher:
CDS
Description:
The blazar OJ 287 has shown a ~~12 year quasi-periodicity over more than a century, in addition to the common properties of violent variability in all frequency ranges. It is the strongest known candidate to have a binary singularity in its central engine. We aim to better understand the different emission components by searching for correlated variability in the flux over four decades of frequency measurements. We combined data at frequencies from the millimetric to the visible to characterise the multifrequency light curve in April and May 2010. This includes the only photometric observations of OJ 287 made with the Herschel Space Observatory: five epochs of data obtained over 33 days at 250, 350, and 500um with Herschel-SPIRE. Although we find that the variability at 37GHz on timescales of a few weeks correlates with the visible to near-IR spectral energy distribution (SED), there is a small degree of reddening in the continuum at lower flux levels that is revealed by the decreasing rate of decline in the light curve at lower frequencies. However, we see no clear evidence that a rapid flare detected in the light curve during our monitoring in the visible to near-IR light curve is seen either in the Herschel data or at 37GHz, suggesting a low-frequency cut-off in the spectrum of such flares. We see only marginal evidence of variability in the observations with Herschel over a month, although this may be principally due to the poor sampling. The spectral energy distribution between 37 GHz and the visible can be characterised by two components of approximately constant spectral index: a visible to far-IR component of spectral index {alpha}=-0.95, and a far-IR to millimetric spectral index of {alpha}=0.43. There is no evidence of an excess of emission that would be consistent with the 60um dust bump found in many active galactic nuclei.
4668. OJ 287 flux & polarization during 2016 outburst
ID:
ivo://CDS.VizieR/J/ApJ/835/275
Title:
OJ 287 flux & polarization during 2016 outburst
Short Name:
J/ApJ/835/275
Date:
21 Oct 2021
Publisher:
CDS
Description:
The gamma-ray blazar OJ 287 was in a high activity state during 2015 December-2016 February. Coinciding with this high brightness state, we observed this source for photometry on 40 nights in R-band and for polarimetry on nine epochs in UBV RI bands. During the period of our observations, the source brightness varied from 13.20+/-0.04 mag to 14.98+/-0.04mag and the degree of polarization (P) fluctuated between 6.0%+/-0.3% and 28.3%+/-0.8% in R-band. Focusing on intranight optical variability (INOV), we find a duty cycle of about 71% using {chi}^2^-statistics, similar to that known for blazars. From INOV data, the shortest variability timescale is estimated to be 142+/-38min, yielding a lower limit of the observed Doppler factor {delta}_0_=1.17, the magnetic field strength B<=3.8G, and the size of the emitting region R_s_<2.28x10^14^cm. On internight timescales, a significant anticorrelation between R-band flux and P is found. The observed P at U-band is generally larger than that observed at longer-wavelength bands, suggesting a wavelength-dependent polarization. Using V-band photometric and polarimetric data from Steward Observatory obtained during our monitoring period, we find a varied correlation between P and V-band brightness. While an anticorrelation is sometimes seen between P and V-band magnitude, no correlation is seen at other times, thereby suggesting the presence of more than one short-lived shock component in the jet of OJ 287.
4669. Old globular clusters in dwarf irregular galaxies
ID:
ivo://CDS.VizieR/J/AJ/135/1858
Title:
Old globular clusters in dwarf irregular galaxies
Short Name:
J/AJ/135/1858
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have performed a search for old globular clusters (GCs) using archival F606W and F814W Hubble Space Telescope/Advanced Camera for Surveys images of 19 Magellanic-type dwarf Irregular (dIrr) galaxies. Those dIrrs reside in nearby (2-8Mpc) associations of dwarf galaxies only. All dIrrs have absolute magnitudes fainter than or equal to that of the SMC (M_V_=-16.2mag). We detect in total 50 GC candidates in 13 dIrrs, of which 37 have (V-I) colors consistent with "blue" (old, metal-poor) GCs (bGCs). The luminosity function (LF) of the bGC candidates in our sample shows a turnover magnitude of M_V_=-7.41+/-0.22mag, consistent with other galaxy types.
4670. Old MS stars in young moving groups
ID:
ivo://CDS.VizieR/J/A+A/499/129
Title:
Old MS stars in young moving groups
Short Name:
J/A+A/499/129
Date:
21 Oct 2021
Publisher:
CDS
Description:
The associations and moving groups of young stars are excellent laboratories to investigate the stellar formation in the solar neighborhood. Past results confirmed that a non-negligible fraction of old main-sequence stars is present in the lists of members of the young stellar kinematic groups. A detailed study on the properties of these samples is needed to separate the young stars from old main-sequence stars with similar space motion, in order to identify the origin of these structures. Our intention is to characterize the sample of stars members of the young moving groups and determine their age distribution to quantify the contamination by old main-sequence stars, in particular, in the Local Association. For our study, we used the sample of stars possible members of the young (~10-650Myr) moving groups from the literature. In order to determine the age of the stars, we used several age indicators well suited for young main sequence stars: X-ray fluxes from the Rosat All-sky Survey database, photometric data from the Tycho-2, Hipparcos, and 2MASS database. We also used spectroscopic data, in particular the equivalent width of the lithium line LiI lambda6707.8{AA} and Halpha, to constrain the range of ages of the stars in the sample. The combination of photometric and spectroscopic data permitted to separate the young stars (10-650Myr) from the old (>1Gyr) field ones. In particular, the member list of the Local Association results contaminated by ~30% of old field stars. This value must be considered as the contamination of our particular sample, not to the entire Local Association. In other young moving groups it is more difficult to estimate the fraction of old stars in the samples of possible members. However, the X-ray emission level can help to separate, at least, two age populations: stars with 200Myr and stars older than this. The samples of candidates of the classical moving groups contain a non-negligible amount of old field stars that should be considered in studies on the stellar birthrate in the solar neighborhood. Our results agree with the scenario of the moving groups being composed by groups of young stars formed in a recent star formation episode and old field stars with similar space motion. Only combining both X-ray and optical spectroscopic data it is possible to distinguish between the two age populations.