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5521. Red and infrared polarimetry in galactic plane
ID:
ivo://CDS.VizieR/J/AJ/110/268
Title:
Red and infrared polarimetry in galactic plane
Short Name:
J/AJ/110/268
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present VRIJHK polarimetry and JHK photometry of highly reddened stars found in an objective prism survey published by Stephenson (1992AJ....103..263S). The JHK colors of these stars are consistent with interstellar extinction as the dominant source of the reddening. The distribution of the polarization position angles in Galactic coordinates is very similar to previous optical polarimetry surveys such as Mathewson & Ford ([MNRAS, 74, 139 (1970)]. However, for the redder stars with IR polarimetry, the polarization strength is moderately lower than expected for the amount of extinction. We postulate that the line of sight to many of these stars samples specific regions where the grain population has poor polarizing properties, while the remainder of the line of sight is similar to the paths sampled by previous optical surveys. The wavelength dependence of the polarization from 1-2.5{mu}m for this sample of stars shows weak evidence for a greater departure from the mean for interstellar polarization than for most published near-infrared polarimetry.
5522. Red clump stars in Galactic Bulge from OGLE-III
ID:
ivo://CDS.VizieR/J/ApJ/721/L28
Title:
Red clump stars in Galactic Bulge from OGLE-III
Short Name:
J/ApJ/721/L28
Date:
21 Oct 2021
Publisher:
CDS
Description:
The red clump (RC) is found to be split into two components along several sightlines toward the Galactic bulge. This split is detected with high significance toward the areas (-3.5<l<1,b<-5) and (l,b)=(0,+5.2), i.e., along the bulge minor axis and at least 5 deg off the plane. The fainter (hereafter "main") component is the one that more closely follows the distance-longitude relation of the bulge RC. The main component is ~0.5mag fainter than the secondary component and with an overall approximately equal population. For sightlines further from the plane, the difference in brightness increases, and more stars are found in the secondary component than in the main component. The two components have very nearly equal (V-I) color.
5523. Reddening and extinction at high galactic latitude
ID:
ivo://CDS.VizieR/J/ApJ/623/897
Title:
Reddening and extinction at high galactic latitude
Short Name:
J/ApJ/623/897
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present near-infrared (JHKL) photometry of 103 southern stars located behind translucent interstellar clouds at high Galactic latitude. Our data are combined with visual photometry and spectral type information from the literature in a detailed analysis of the wavelength dependence of interstellar extinction by dust in these high-latitude clouds. We investigate the shape of the near-infrared extinction curve and evaluate the total line-of-sight extinction (A_V_) and ratio of total-to-selective extinction (R_V_) in each line of sight.
5524. Reddening and metallicity of NGC 6752
ID:
ivo://CDS.VizieR/J/A+A/440/901
Title:
Reddening and metallicity of NGC 6752
Short Name:
J/A+A/440/901
Date:
21 Oct 2021
Publisher:
CDS
Description:
Accurate reddenings for Globular Clusters could be obtained by comparing the colour-temperature obtained using temperatures from reddening-free indicator (H{alpha}), with that given by standard colour-temperature calibrations. The large multiplexing opportunity offered by FLAMES at VLT2 allowed us to obtain spectra centered on H{alpha} at a resolution of R=6000 and 5<S/N<50 for 120 stars near the turn-off of NGC 6752 with GIRAFFE from a single 1300 seconds exposure on June 24th, 2004.
5525. Reddening, distance modulus & Fe/H of RRLs in w Cen
ID:
ivo://CDS.VizieR/J/ApJ/870/115
Title:
Reddening, distance modulus & Fe/H of RRLs in w Cen
Short Name:
J/ApJ/870/115
Date:
21 Oct 2021
Publisher:
CDS
Description:
We developed a new approach to provide accurate estimates of the metal content, reddening, and true distance modulus of RR Lyrae stars (RRLs). The method is based on homogeneous optical (BVI) and near-infrared (JHK) mean magnitudes and on predicted period-luminosity-metallicity relations (IJHK) and absolute mean magnitude-metallicity relations (BV). We obtained solutions for three different RRL samples in {omega}Cen: first overtone (RRc, 90), fundamental (RRab, 80), and global (RRc+RRab) in which the period of first overtones were fundamentalized. The metallicity distribution shows a well defined peak at [Fe/H]~-1.98 and a standard deviation of {sigma}=0.54dex. The spread is, as expected, metal-poor ([Fe/H]<=-2.3) objects. The current metallicity distribution is ~0.3dex more metal-poor than similar estimates for RRLs available in the literature. The difference vanishes if the true distance modulus we estimated is offset by -0.06/-0.07mag in true distance modulus. We also found a cluster true distance modulus of {mu}=13.720{+/-}0.002{+/-}0.030mag, where the former error is the error on the mean and the latter is the standard deviation. Moreover, we found a cluster reddening of E(B-V)=0.132{+/-}0.002{+/-}0.028mag and spatial variations of the order of a few arcmin across the body of the cluster. Both the true distance modulus and the reddening are slightly larger than similar estimates available in the literature, but the difference is within 1{sigma}. The metallicity dependence of distance diagnostics agrees with theory and observations, but firm constraints require accurate and homogeneous spectroscopic measurements.
5526. Reddening law of type Ia supernovae
ID:
ivo://CDS.VizieR/J/A+A/529/L4
Title:
Reddening law of type Ia supernovae
Short Name:
J/A+A/529/L4
Date:
21 Oct 2021
Publisher:
CDS
Description:
We employ 76 type Ia supernovae (SNe Ia) with optical spectrophotometry within 2.5 days of B-band maximum light obtained by the Nearby Supernova Factory to derive the impact of Si and Ca features on the supernovae intrinsic luminosity and determine a dust reddening law. We use the equivalent width of SiII {lambda}4131 in place of the light curve stretch to account for first-order intrinsic luminosity variability. The resulting empirical spectral reddening law exhibits strong features that are associated with CaII and SiII {lambda}6355. After applying a correction based on the CaII H&K equivalent width we find a reddening law consistent with a Cardelli extinction law. Using the same input data, we compare this result to synthetic rest-frame UBVRI-like photometry to mimic literature observations.
5527. Red giant candidates in 10 open clusters
ID:
ivo://CDS.VizieR/J/AN/329/609
Title:
Red giant candidates in 10 open clusters
Short Name:
J/AN/329/609
Date:
21 Oct 2021
Publisher:
CDS
Description:
As part of a long-term project to determine abundances and astrophysical properties of evolved red stars in open clusters, we present high-precision DDO photoelectric observations for a sample of 33 red giant candidates projected in the fields of nine Galactic open clusters. These data are supplemented with UBV photoelectric photometry of 24 of these stars as well as with CORAVEL radial-velocity observations for 13 red giant candidates in four of the clusters. We also present Washington photoelectric photometry of a small sample of red giant candidates of the open cluster Ruprecht 97. The likelihood of cluster membership for each star photometrically observed and for 23 additional red giant candidates with UBV and DDO data available in the literature, is evaluated by using two independent photometric criteria. Nearly 82% of the analysed stars are found to have a high probability of being cluster giants. Photometric membership probabilities show very good agreement with those obtained from CORAVEL radial velocities. While E(B-V) colour excesses were determined from combined B-V and DDO colours, calibrations of the DDO system were used to derive MK spectral types, effective temperatures and metallicities.The derived DDO metallicities range between values typical of moderately metal-poor clusters ([Fe/H]=-0.19) to moderately metal-rich ([Fe/H]=0.25) ones.
5528. Red giant stars in clusters. II. M13 and M92
ID:
ivo://CDS.VizieR/J/AJ/137/4282
Title:
Red giant stars in clusters. II. M13 and M92
Short Name:
J/AJ/137/4282
Date:
21 Oct 2021
Publisher:
CDS
Description:
High-resolution spectra of 123 red giant stars in the globular cluster M13 and 64 red giant stars in M92 were obtained with Hectochelle at the MMT telescope. Emission and line asymmetries in H{alpha} and CaIIK are identified, characterizing motions in the extended atmospheres and seeking differences attributable to metallicity in these clusters and M15. On the red giant branch, emission in H{alpha} generally appears in stars with T_eff_<~4500K and logL/L_{sun}_>~2.75. Fainter stars showing emission are asymptotic giant branch (AGB) stars or perhaps binary stars. The line-bisector for H{alpha} reveals the onset of chromospheric expansion in stars more luminous than log(L/L_{sun}_)~2.5 in all clusters, and this outflow velocity increases with stellar luminosity. However, the coolest giants in the metal-rich M13 show greatly reduced outflow in H{alpha} most probably due to decreased T_eff_ and changing atmospheric structure. The CaIIK_3_ outflow velocities are larger than shown by H{alpha} at the same luminosity and signal accelerating outflows in the chromospheres. Stars clearly on the AGB show faster chromospheric outflows in H{alpha} than RGB objects. While the H{alpha} velocities on the RGB are similar for all metallicities, the AGB stars in the metal-poor M15 and M92 have higher outflow velocities than in the metal-rich M13. Comparison of these chromospheric line profiles in the paired metal-poor clusters, M15 and M92, shows remarkable similarities in the presence of emission and dynamical signatures, and does not reveal a source of the "second-parameter" effect.
5529. Red giant stellar parameters in the LMC bar
ID:
ivo://CDS.VizieR/J/AJ/153/261
Title:
Red giant stellar parameters in the LMC bar
Short Name:
J/AJ/153/261
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report new spectroscopic observations obtained with the Michigan/Magellan Fiber System of 308 red giants (RGs) located in two fields near the photometric center of the bar of the Large Magellanic Cloud. This sample consists of 131 stars observed in previous studies (in one field) and 177 newly observed stars (in the second field) selected specifically to more reliably establish the metallicity and age distributions of the bar. For each star, we measure its heliocentric line-of-sight velocity, surface gravity, and metallicity from its high-resolution spectrum (effective temperatures come from photometric colors). The spectroscopic Hertzsprung-Russell diagrams- modulo small offsets in surface gravities-reveal good agreement with model isochrones. The mean metallicity of the 177-RG sample is [Fe/H]=-0.76+/-0.02 with a metallicity dispersion {sigma}=0.28+/-0.03. The corresponding metallicity distribution-corrected for selection effects-is well fitted by two Gaussian components: one metal-rich with a mean -0.66+/-0.02 and a standard deviation 0.17+/-0.01, and the other metal-poor with -1.20+/-0.24 and 0.41+/-0.06. The metal-rich and metal-poor populations contain approximately 85% and 15% of stars, respectively. We also confirm that the velocity dispersion in the bar center decreases significantly from 31.2+/-4.3 to 18.7+/-1.9km/s with increasing metallicity over the range -2.09 to -0.38. Individual stellar masses are estimated using the spectroscopic surface gravities and the known luminosities. We find that lower mass, hence older, RGs have larger metallicity dispersion and lower mean metallicity than the higher-mass, younger RGs. The estimated masses, however, extend to implausibly low values (~0.1M_{sun}_), making it impossible to obtain an absolute age-metallicity or age distribution of the bar.
5530. Red giant variable candidates in UMi dSph
ID:
ivo://CDS.VizieR/J/ApJ/617/L41
Title:
Red giant variable candidates in UMi dSph
Short Name:
J/ApJ/617/L41
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have analyzed two epochs of Hubble Space Telescope Wide Field Planetary Camera 2 observations of the Ursa Minor dwarf spheroidal galaxy using the HSTphot photometric reduction package. We report the detection of nine faint (M_V_>~0.0mag) red giant variable stars that exhibit low-amplitude brightness fluctuations on 10 minute timescales with amplitudes ranging from 36 to 130mmag.