- ID:
- ivo://CDS.VizieR/J/A+A/446/773
- Title:
- GLMP sample of galactic OH/IR stars
- Short Name:
- J/A+A/446/773
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present optical and near-infrared finding charts taken from the DSS and 2MASS surveys of 94 IRAS sources selected from the GLMP catalogue, and accurate astrometry (~0.2") for most of them. Selection criteria were very red IRAS colours representative for OH/IR stars with optically thick circumstellar shells and the presence of variability according to the IRAS variability index (VAR>50). The main photometric properties of the stars in this `GLMP sample' are presented, discussed and compared with the correspondent properties of the `Arecibo sample' of OH/IR stars studied nearlier. We find that 37% of the sample (N=34) has no counterpart in the 2MASS, implying extremely high optical depths of their shells. Most of the sources identified in the 2MASS are faint (K>~8) and are of very red colour in the near-infrared, as expected. The brightest 2MASS counterpart (K=5.3mag) was found for IRAS18299-1705. Its blue colour H-K=1.3 suggests that IRAS18299-1705 is a post-AGB star. Few GLMP sources have faint but relatively blue counterparts. They might be misidentified field stars or stars that recently experienced a drop of their mass loss rates. The `GLMP sample' in general is made of oxygen-rich AGB stars, which are highly obscured by their circumstellar shells. They belong to the same population as the reddest OH/IR stars in the `Arecibo sample'.
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Search Results
- ID:
- ivo://CDS.VizieR/J/other/NewA/88.J1607
- Title:
- Globular cluster NGC 6397 variable stars
- Short Name:
- J/other/NewA/88.
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- We present a new time-series VI CCD photometry of the globular cluster NGC 6397, from which we obtained and analysed the light curves of 35 variables carefully identified in the cluster field. We assessed the membership of the variables with an astrometric analysis based on Gaia DR2 data. The cluster colour-magnitude diagram was differentially de- reddened and cleaned of non members, which allowed us to fit isochrones for [Fe/H]=-2.0dex in the range 13.0-13.5Gyr, for a mean reddening E(B-V)=0.19, and a distance of 2.5kpc. This distance was confirmed using the period-luminosity relation for the cluster's five SX Phoenicis variables (V10, V11, V15, V21, and V23) present among its blue stragglers, yielding 2.24+/-0.13kpc. We also modelled the light curves of four eclipsing binaries (V4, V5, V7, and V8), and gave the parameters of the systems; the contact binaries V7 and V8 have distances consistent with that of the cluster. NGC 6397 appears to harbour no RR Lyrae stars, being its horizontal branch remarkably blue, much like that of its analogous cluster, M10. To match the blue tail of the horizontal branch population, models of 0.64-0.66M_{sun}_ with mass loss at the RGB are required, indicating rather thin shell masses for horizontal branch stars.
- ID:
- ivo://CDS.VizieR/J/AJ/149/183
- Title:
- gri photometry of variables in NGC 4258
- Short Name:
- J/AJ/149/183
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results of a ground-based survey for Cepheid variables in NGC4258. This galaxy plays a key role in the Extragalactic Distance Scale due to its very precise and accurate distance determination via very long baseline interferometry observations of water masers. We imaged two fields within this galaxy using the Gemini North telescope and the Gemini Multi-Object Spectrograph, obtaining 16 epochs of data in the Sloan Digital Sky Survey gri bands over 4yr. We carried out point-spread function photometry and detected 94 Cepheids with periods between 7 and 127 days, as well as an additional 215 variables which may be Cepheids or Population II pulsators. We used the Cepheid sample to test the absolute calibration of theoretical gri Period-Luminosity relations and found good agreement with the maser distance to this galaxy. The expected data products from the Large Synoptic Survey Telescope should enable Cepheid searches out to at least 10Mpc.
- ID:
- ivo://CDS.VizieR/J/other/JAD/14.1
- Title:
- GSC04778-00152 photometry and spectroscopy
- Short Name:
- J/other/JAD/14.1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Photometric and spectroscopic data of the southern contact binary GSC 04778-00152 are presented. Six new times of minimum are listed. For modelling purposes, we provide UBVRI phase diagrams of the contact binary with the contribution of the nearby companion removed.
- ID:
- ivo://CDS.VizieR/J/other/JAD/16.1
- Title:
- GSC 8613-2122 UBVRI and uvby light curves
- Short Name:
- J/other/JAD/16.1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a collection of more than 4000 UBVRI and uvby differential photometric measurements of the newly-discovered 12th-magnitude southern Delta Scuti star GSC 08613-02122. The star has a main pulsation period of about 4 hours with an amplitude of 0.05m in the V band. The pulsation amplitude is variable, and the O-C diagram reveals the existence of a long P~29.5-day cycle, which possibly results from the beating of the main pulsation frequency with a nearby frequency.
- ID:
- ivo://CDS.VizieR/J/AJ/134/1579
- Title:
- Halo stars in solar neighborhood
- Short Name:
- J/AJ/134/1579
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have assembled a sample of halo stars in the solar neighborhood to look for halo substructure in velocity and angular momentum space. Our sample (231 stars) includes red giants, RR Lyrae variable stars, and red horizontal branch stars within 2.5kpc of the Sun with [Fe/H] less than -1.0. It was chosen to include stars with accurate distances, space velocities, and metallicities, as well as well-quantified errors. With our data set, we confirm the existence of the streams found by Helmi and coworkers (1999Natur.402...53H), which we refer to as the H99 streams.
- ID:
- ivo://CDS.VizieR/J/other/IBVS/4678
- Title:
- Haro-Chavira infrared stars identifications
- Short Name:
- J/other/IBVS/467
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The first seven extremely-red Haro-Chavira stars were published by Johnson et al. (1965ApJ...142.1249J), which includes BVRIJHKLMN photometry for them. The positions listed for these stars are consistently nearly a full degree in error, as a consequence of which they seem to have been overlooked in later literature. The offsets are parallel to the direction of precession, and the error evidently arises from the application of 100 years of precession motion with the wrong sign. These stars were unambiguously identified using the published charts, which are copied from the POSS-I prints of the region. In a follow-up work, Chavira (1967BOTT....4..197C) published a more extensive list of stars based on far-red objective-prism and direct plates. The main difficulty in the identifications was the poor positions, some in error by 10'. The finder charts were thus indispensable for positive identification on the sky. Two stars (HC 56 and HC 62) defeated my attempts to locate them.
- ID:
- ivo://CDS.VizieR/J/AJ/155/203
- Title:
- HARPS-N RVs & activity indicators for Kepler-1655
- Short Name:
- J/AJ/155/203
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the confirmation of a small, moderately irradiated (F=155+/-7 F_{Earth}_) Neptune with a substantial gas envelope in a P=11.8728787+/-0.0000085 day orbit about a quiet, Sun-like G0V star Kepler-1655. Based on our analysis of the Kepler light curve, we determined Kepler-1655b's radius to be 2.213+/-0.082 R_{Earth}_. We acquired 95 high-resolution spectra with Telescopio Nazionale Galileo/HARPS-N, enabling us to characterize the host star and determine an accurate mass for Kepler-1655b of 5.0_-2.8_^+3.1^ M_{Earth}_ via Gaussian-process regression. Our mass determination excludes an Earth-like composition with 98% confidence. Kepler-1655b falls on the upper edge of the evaporation valley, in the relatively sparsely occupied transition region between rocky and gas-rich planets. It is therefore part of a population of planets that we should actively seek to characterize further.
- ID:
- ivo://CDS.VizieR/J/A+A/489/1255
- Title:
- HARPS observations of eight galactic Cepheids
- Short Name:
- J/A+A/489/1255
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We show that residual {gamma}-velocities (compared to a axisymmetric rotation model of the milky Way) are an intrinsic property of Cepheids. We observed eight galactic Cepheids with the HARPS spectroscope, focusing specifically on 17 spectral lines. For each spectral line of each star, we computed the {gamma}-velocity (resp. {gamma}-asymmetry) as an average value of the interpolated radial velocity (resp. line asymmetry) curve. For each Cepheid in our sample, a linear relation is found between the {gamma}-velocities of the various spectral lines and their corresponding {gamma}-asymmetries, showing that residual {gamma}-velocities stem from the intrinsic properties of Cepheids. We also provide a physical reference to the stellar {gamma}-velocity: it should be zero when the {gamma}-asymmetry is zero. Following this definition, we provide very precise and physically calibrated estimates of the {gamma}-velocities for all stars of our sample.
- ID:
- ivo://CDS.VizieR/J/A+A/453/309
- Title:
- HARPS observations of nine galactic Cepheids
- Short Name:
- J/A+A/453/309
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The ratio of pulsation to radial velocity (the projection factor) is currently limiting the accuracy of the Baade-Wesselink method, and in particular of its interferometric version recently applied to several nearby Cepheids. This work aims at establishing a link between the line asymmetry evolution over the Cepheids' pulsation cycles and their projection factor, with the final objective to improve the accuracy of the Baade-Wesselink method for distance determinations. We present HARPS high spectral resolution observations (R=120000) of nine galactic Cepheids: R Tra, S Cru, Y Sgr, beta Dor, zeta Gem, Y Oph, RZ Vel, l Car and RS Pup, having a good period sampling (P=3.39d to P=41.52d). We fit spectral line profiles by an asymmetric bi-Gaussian to derive radial velocity, Full-Width at Half-Maximum in the line (FWHM) and line asymmetry for all stars.
