- ID:
- ivo://CDS.VizieR/J/MNRAS/455/2216
- Title:
- Outer bulge O-rich Mira's JHKL photometry
- Short Name:
- J/MNRAS/455/2216
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report periods and JHKL observations for 643 oxygen-rich Mira variables found in two outer bulge fields at b=-7{deg} and l=+/-8{deg} and combine these with data on 8057 inner bulge Miras from the OGLE, Macho and 2MASS surveys, which are concentrated closer to the Galactic centre. Distance moduli are estimated for all these stars. Evidence is given showing that the bulge structure is a function of age. The longer period Miras (LogP>2.6, age~5Gyr and younger) show clear evidence of a bar structure inclined to the line of sight in both the inner and outer regions. The distribution of the shorter period (metal-rich globular cluster age) Miras, appears spheroidal in the outer bulge. In the inner region these old stars are also distributed differently from the younger ones and possibly suggest a more complex structure. These data suggest a distance to the galactic centre R_0_, of 8.9kpc, with an estimated uncertainty of ~0.4kpc. The possible effect of helium enrichment on our conclusions is discussed.
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/444/3301
- Title:
- Oxygen abundance in Galactic disc Cepheids
- Short Name:
- J/MNRAS/444/3301
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We performed a non-local thermodynamic equilibrium (NLTE) analysis of the infrared oxygen triplet for a large number of Cepheid spectra obtained with the Hobby-Eberly Telescope. These data were combined with our previous NLTE results for stars observed with the Max Planck Gesellschaft Telescope with the aim of investigating the oxygen abundance distribution in the Galactic thin disc. We found the slope of the radial (O/H) distribution to be equal -0.058dex/kpc. However, we found some evidence that the distribution might become flatter in the outer parts of the disc. This is supported by the results of other authors who have studied open clusters, planetary nebulae and Hii regions. Some mechanisms of flattening are discussed.
- ID:
- ivo://CDS.VizieR/J/A+A/423/677
- Title:
- Oxygen abundances in chromospherically active stars
- Short Name:
- J/A+A/423/677
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We discuss oxygen abundances derived from [O I] 6300 and the O I triplet in stars spanning a wide range in chromospheric activity level, and show that these two indicators yield increasingly discrepant results with higher chromospheric/coronal activity measures. While the forbidden and permitted lines give fairly consistent results for solar-type disk dwarfs, spuriously high O I triplet abundances are observed in young Hyades and Pleiades stars, as well as in individual components of RS CVn binaries (up to 1.8dex). The distinct behaviour of the [O I]-based abundances which consistently remain near-solar suggests that this phenomenon mostly results from large departures from LTE affecting the O I triplet at high activity level that are currently unaccounted for, but also possibly from a failure to adequately model the atmospheres of K-type stars. These results suggest that some caution should be exercised when interpreting oxygen abundances in active binaries or young open cluster stars.
- ID:
- ivo://CDS.VizieR/J/ApJS/119/141
- Title:
- Oxygen-rich dust shells IR spectral classification
- Short Name:
- J/ApJS/119/141
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper presents infrared spectral classifications for a flux-limited sample of 635 optically identified oxygen-rich variables including supergiants and sources on the asymptotic giant branch (AGB). Several classes of spectra from oxygen-rich dust exist, and these can be arranged in a smoothly varying sequence of spectral shapes known as the silicate dust sequence. Classification based on this sequence reveals several dependencies of the dust emission on the properties of the central star. Nearly all S stars show broad emission features from alumina dust, while most of the supergiants exhibit classic features from amorphous silicate dust. Mira variables with symmetric light curves generally show broad alumina emission, while those with more asymmetric light curves show classic silicate emission. These differences may arise from differences in the photospheric C/O ratio.
- ID:
- ivo://CDS.VizieR/J/PAZh/27/132
- Title:
- Parameters of RR Lyrae Type Variables
- Short Name:
- J/PAZh/27/132
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The method of statistical parallaxes is applied to a sample of 262 Rrab RR Lyr type variables with published photoelectric photometry, radial velocities, abundances and with known absolute proper motions. The proper motions are adopted from the Hipparcos, PPM, NPM1, and the Four-Million Catalog (Volchkov et al. 1992, Ed. by A.P.Gulyaev and V.V. Nesterov, Mosk. Gos. Univ., Moscow, p. 67) and in the case the last three catalogs are reduced to the Hipparcos system. The parameters of the velocity distribution of halo (U0, V0, W0) = ( -9+/-12, -214+/-10, -16+/-7) km/s and thick-disk (U0, V0, W0) = (-16+/-8, -41+/-7, -18+/-5) km/s RR Lyrae subsamples are inferred as well as the intensity-averaged absolute magnitudes of the corresponding populations: <MV> = 0.77+/-0.10 and <MV> = +1.11+/-0.28 for halo and thickdisk objects, respectively.
- ID:
- ivo://CDS.VizieR/J/ApJ/689/L149
- Title:
- Parameter variations of Gliese 436b transits
- Short Name:
- J/ApJ/689/L149
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present ground-based observations of the transiting Neptune-mass planet Gl 436b obtained with the 3.5m telescope at Apache Point Observatory and other supporting telescopes. Included in this is an observed transit in early 2005, over 2 years before the earliest reported transit detection. We have compiled all available transit data to date and perform a uniform modeling using the JKTEBOP code. We do not detect any transit timing variations of amplitude greater than ~1 minute over the ~3.3 year baseline. We do however find possible evidence for a self-consistent trend of increasing orbital inclination, transit width, and transit depth, which supports the supposition that Gl 436b is being perturbed by another planet of <~12M_{earth}_ in a nonresonant orbit.
- ID:
- ivo://CDS.VizieR/II/171
- Title:
- Parenago Catalog of Stars in Orion Nebula
- Short Name:
- II/171
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The present catalogue is a machine-readable version of the catalogue of stars in the area of the Orion nebula, published by P.P. Parenago (1954). The sky area between 5h 24m and 5h 36m in right ascension (1900.0) and between -4 and -7 degrees in declination (1900.0), containing the Orion nebula, has been investigated in that work. Ten of variable stars in original Parenago (1954) catalogue had CSV numbers (Kukarkin et al., 1951) but since that time all of them were confirmed as variables and included in GCVS (Kholopov et al., 1985a&b, 1987). We superseded CSV-numbers by GCVS-names in the machine-readable version for the following stars: ------------------------------------------------ Number in CSV-number GCVS-name the catalogue ------------------------------------------------ 1605 606 V372 ORI 1613 607 V373 ORI 1635 608 V374 ORI 1713 609 V375 ORI 1748 610 V387 ORI 1762 100569 V376 ORI 1974 617 V377 ORI 2183 625 V388 ORI 2393 630 V380 ORI 2478 634 V381 ORI ------------------------------------------------
- ID:
- ivo://CDS.VizieR/J/A+A/640/A13
- Title:
- Par-Lup3-4 CO ALMA images
- Short Name:
- J/A+A/640/A13
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Very low-mass stars are known to have jets and outflows, which is indicative of a scaled-down version of low-mass star formation. However, only very few outflows in very low-mass sources are well characterized. We characterize the bipolar molecular outflow of the very low-mass star Par-Lup3-4, a 0.12M_{sun}_ object known to power an optical jet. We observed Par-Lup3-4 with ALMA in Bands 6 and 7, detecting both the continuum and CO molecular gas. In particular, we studied three main emission lines: CO(2-1), CO(3-2), and ^13^CO(3-2). Our observations reveal for the first time the base of a bipolar molecular outflow in a very low-mass star, as well as a stream of material moving perpendicular to the primary outflow of this source. The primary outflow morphology is consistent with the previously determined jet orientation and disk inclination. The outflow mass is 9.5x10^-7^M_{sun}_, with an outflow rate of 4.3x10^-9^M_{sun}_/yr. A new fitting to the spectral energy distribution suggests that Par-Lup3-4 may be a binary system. We have characterized Par-Lup3-4 in detail, and its properties are consistent with those reported in other very low-mass sources. This source provides further evidence that very low-mass sources form as a scaled-down version of low-mass stars.
- ID:
- ivo://CDS.VizieR/J/A+A/480/495
- Title:
- Patterns of color variations in close binaries
- Short Name:
- J/A+A/480/495
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This is the first of a series of papers in which we present the results of a long-term photometric monitoring project carried out at Catania Astrophysical Observatory aimed at studying magnetic activity in late-type components of close binary systems, its dependence on global stellar parameters, and its evolution on different time scales from days to years. In this first paper, we present the complete observation dataset and new results of an investigation into the origin of brightness and color variations observed in the well-known magnetically active close binary stars: AR Psc, VY Ari, UX Ari, V711 Tau, EI Eri, V1149 Ori, DH Leo, HU Vir, RS CVn, V775 Her, AR Lac, SZ Psc, II Peg and BY Dra . About 38000 high-precision photoelectric nightly observations in the U, B and V filters are analysed. Correlation and regression analyses of the V magnitude vs. U-B and B-V color variations are carried out and a comparison with model variations for a grid of active region temperature and filling factor values is also performed. We find the existence of two different patterns of color variation. Eight stars in our sample: BY Dr, VY Ari, V775 Her, II Peg, V1149 Ori, HU Vir, EI Eri and DH Leo become redder when they become fainter, as is expected from the presence of active regions consisting of cool spots. The other six stars show the opposite behaviour, i.e. they become bluer when they become fainter. For V711 Tau this behaviour could be explained by the increased relative U- and B- flux contribution by the earlier-type component of the binary system when the cooler component becomes fainter. On the other hand, for AR Psc, UX Ari, RS CVn, SZ Psc and AR Lac the existence of hot photospheric faculae must be invoked. We also found that in single-lined and double-lined binary stars in which the fainter component is inactive or much less active the V magnitude is correlated to B-V and U-B color variations in more than 60% of observation seasons. The correlation is found in less than 40% of observation seasons when the fainter component has a non-negligible level of activity and/or hot faculae are present but they are either spatially or temporally uncorrelated to spots.
- ID:
- ivo://CDS.VizieR/J/AJ/139/2269
- Title:
- P Cyg H{alpha} squared visibility
- Short Name:
- J/AJ/139/2269
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- High spatial resolution observations of the H{alpha}-emitting wind structure associated with the luminous blue variable star P Cygni were obtained with the Navy Prototype Optical Interferometer. These observations represent the most comprehensive interferometric data set on P Cyg to date. We demonstrate how the apparent size of the H{alpha}-emitting region of the wind structure of P Cyg compares between the 2005, 2007, and 2008 observing seasons and how this relates to the H{alpha} line spectroscopy. Using the data sets from 2005, 2007, and 2008 observing seasons, we fit a circularly symmetric Gaussian model to the interferometric signature from the H#-emitting wind structure of P Cyg.
