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2241. Revised HIP periods for long-period variables
ID:
ivo://CDS.VizieR/J/A+A/403/993
Title:
Revised HIP periods for long-period variables
Short Name:
J/A+A/403/993
Date:
21 Oct 2021
Publisher:
CDS
Description:
We analyse the K-band luminosities of a sample of galactic long-period variables using parallaxes measured by the Hipparcos mission. The parallaxes are in most cases re-computed from the Hipparcos Intermediate Astrometric Data using improved astrometric fits and chromaticity corrections. The K band magnitudes are taken from the literature and from measurements by COBE, and are corrected for interstellar and circumstellar extinction. The sample contains stars of several spectral types: M, S and C, and of several variability classes: Mira, semiregular SRa, and SRb. We find that the distribution of stars in the period-luminosity plane is independent of circumstellar chemistry, but that the different variability types have different P-L distributions. Both the Mira variables and the SRb variables have reasonably well-defined period-luminosity relationships, but with very different slopes. The SRa variables are distributed between the two classes, suggesting that they are a mixture of Miras and SRb, rather than a separate class of stars. New period-luminosity relationships are derived based on our revised Hipparcos parallaxes. The Miras show a similar period-luminosity relationship to that found for Large Magellanic Cloud Miras by Feast et al. (1989MNRAS.241..375F).
2242. Revised LGGS UBVRI photometry of M31 and M33 stars
ID:
ivo://CDS.VizieR/J/AJ/152/62
Title:
Revised LGGS UBVRI photometry of M31 and M33 stars
Short Name:
J/AJ/152/62
Date:
21 Oct 2021
Publisher:
CDS
Description:
We describe our spectroscopic follow-up to the Local Group Galaxy Survey (LGGS) photometry of M31 and M33. We have obtained new spectroscopy of 1895 stars, allowing us to classify 1496 of them for the first time. Our study has identified many foreground stars, and established membership for hundreds of early- and mid-type supergiants. We have also found nine new candidate luminous blue variables and a previously unrecognized Wolf-Rayet star. We republish the LGGS M31 and M33 catalogs with improved coordinates, and including spectroscopy from the literature and our new results. The spectroscopy in this paper is responsible for the vast majority of the stellar classifications in these two nearby spiral neighbors. The most luminous (and hence massive) of the stars in our sample are early-type B supergiants, as expected; the more massive O stars are more rare and fainter visually, and thus mostly remain unobserved so far. The majority of the unevolved stars in our sample are in the 20-40M_{Sun}_ range.
2243. Revision of MK luminosity classes
ID:
ivo://CDS.VizieR/J/ApJ/518/859
Title:
Revision of MK luminosity classes
Short Name:
J/ApJ/518/859
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Hipparcos parallaxes of cool giants are utilized in two ways in this paper. First, a plot of reduced parallaxes of stars brighter than 6.5, as a function of spectral type, for the first time separates members of the clump from stars in the main giant ridge. A slight modification of the MK luminosity standards has been made so that luminosity class IIIb defines members of the clump, and nearly all of the class III stars fall within the main giant ridge. Second, a new calibration of MK luminosity classes III and IIIb in terms of visual absolute magnitudes has been made.
2244. Revisiting the Cygnus OB associations
ID:
ivo://CDS.VizieR/J/MNRAS/508/2370
Title:
Revisiting the Cygnus OB associations
Short Name:
J/MNRAS/508/2370
Date:
24 Jan 2022 09:16:32
Publisher:
CDS
Description:
OB associations play an important role in Galactic evolution, though their origins and dynamics remain poorly studied, with only a small number of systems analysed in detail. In this paper we revisit the existence and membership of the Cygnus OB associations. We find that of the historical OB associations only Cyg OB2 and OB3 stand out as real groups. We search for new OB stars using a combination of photometry, astrometry, evolutionary models and an SED fitting process, identifying 4680 probable OB stars with a reliability of >90%. From this sample we search for OB associations using a new and flexible clustering technique, identifying 6 new OB associations. Two of these are similar to the associations Cyg OB2 and OB3, though the others bear no relationship to any existing systems. We characterize the properties of the new associations, including their velocity dispersions and total stellar masses, all of which are consistent with typical values for OB associations. We search for evidence of expansion and find that all are expanding, albeit anistropically, with stronger and more significant expansion in the direction of Galactic longitude. We also identify two large-scale (160pc and 25km/s) kinematic expansion patterns across the Cygnus region, each including three of our new associations, and attribute this to the effects of feedback from a previous generation of stars. This work highlights the need to revisit the existence and membership of the historical OB associations, if they are to be used to study their properties and dynamics.
2245. (RI)c photometry of variables in M31
ID:
ivo://CDS.VizieR/J/A+A/402/113
Title:
(RI)c photometry of variables in M31
Short Name:
J/A+A/402/113
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present Cousins R and I band photometry of variable stars in a ~13'x13' region in the disk of M31 galaxy, obtained during 141 nights. Of the 26 Cepheid variables present in the region, two are newly discovered, 11 are classified as Cepheids for the first time and 13 are confirmed as Cepheids. The extensive photometry of these Cepheids enabled us to determine precise phase and amplitude of pulsation which ranges from 0.11 to 0.48mag in R band. The period of variability ranges from ~7.5 to 56 days. The period-luminosity diagram is used to derive a distance modulus of 24.49+/-0.11mag for M31 galaxy. We also report variability in 333 other stars, of them, 115 stars appear to be long period variables, 2 suspected eclipsing binaries and remaining 216 are irregular variables.
2246. RIJHK photometry of VLM objects near eps Ori
ID:
ivo://CDS.VizieR/J/A+A/429/1007
Title:
RIJHK photometry of VLM objects near eps Ori
Short Name:
J/A+A/429/1007
Date:
21 Oct 2021
Publisher:
CDS
Description:
Coordinates and photometry of very low mass objects near epsilon Ori are presented. The RIJHK photometry of these objects is consistent with membership of the young Ori OB Ib association. Time series observations of this region were carried out using the ESO/MPG WFI at the 2.2-m telescope on La Silla, from 18 to 22 December 2001. In the framework of this monitoring campaign, we obtained deep Cousins R- and I-band images, from which we derived coordinates (columns 2 and 3) as well as photometry in the R- and I-band (columns 4 and 5). Additional near-infrared photometry in J, H, K comes from the 2MASS database (columns 6--8). The cluster member selection is based on a (I,R-I) colour magnitude diagram. The (J-H) colours were used to reject contaminating field stars. The masses given in column 9 were estimated by comparing the near-infrared photometry with the evolutionary tracks of Baraffe et al. (1998A&A...337..403B), assuming an age of 5Myr.
2247. RIJHKs of low-mass stars in sigma Ori
ID:
ivo://CDS.VizieR/J/AN/325/705
Title:
RIJHKs of low-mass stars in sigma Ori
Short Name:
J/AN/325/705
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present an RI photometric survey covering an area of 430 arcmin^2^ around the multiple star sigma Orionis. The observations were conducted with the 0.8m IAC-80 Telescope at the Teide Observatory. The survey limiting R and I magnitudes are 22.5 and 21, and completeness magnitudes 21 and 20, respectively. We have selected 53 candidates from the I vs. R-I colour-magnitude diagram (I=14-20) that follow the previously known photometric sequence of the cluster. Adopting an age of 2-4 Myr for the cluster, we find that these objects span a mass range from 0.35M_{sun}_ to 0.015M_{sun}_. We have performed J-band photometry of 52 candidates and K_s photometry for 12 of them, with the result that 50 follow the expected infrared sequence for the cluster, thus confirming with great confidence that the majority of the candidates are bona fide members. JHK_s photometry from the Two Micron All Sky Survey (2MASS, Cat. <II/246>) is available for 50 of the candidates and are in good agreement with our data. Out of 48 candidates, which have photometric accuracies better than 0.1mag in all bands, only three appear to show near-infrared excesses.
2248. RIK photometry of far-IR sources in NGP
ID:
ivo://CDS.VizieR/J/MNRAS/401/1587
Title:
RIK photometry of far-IR sources in NGP
Short Name:
J/MNRAS/401/1587
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present follow-up observations of the far-infrared (FIR) sources at 90, 150 and 180um detected as part of the ISOPHOT EBL project, which has recently measured the absolute surface brightness of the cosmic infrared background (CIRB) radiation for the first time independently from COBE data. We have observed the fields at the North Galactic Pole region in the optical and near-IR, and complement these data with Sloan Digital Sky Survey photometry, and spectroscopy where available, and present identifications of the 25 FIR sources which reach down to ~150mJy in all three ISOPHOT bands. Identifications are done by means of full spectral energy density fitting to all sources in the FIR error circle areas.
2249. RI photometry in alpha Per and Pleiades
ID:
ivo://CDS.VizieR/J/A+A/416/125
Title:
RI photometry in alpha Per and Pleiades
Short Name:
J/A+A/416/125
Date:
21 Oct 2021
Publisher:
CDS
Description:
Photographic astrometry (proper motions and accurate positions), photometry (in the photographic R and I passbands) and membership probabilities for high probability proper motion members of the clusters Alpha Persei and The Pleiades are presented, along with cross-identifications with names from previously known members in the compilation of Prosser & Stauffer (The Stauffer & Prosser Open Cluster Catalogue, priv.comm.) and their corresponding proper motion membership probabilities according to our study. The SuperCOSMOS facility at the Royal Observatory Edinburgh has (using plates from the United Kingdom Schmidt Telescope) produced complete southern sky surveys in BJ, R and I with an additional second epoch R survey. These surveys are now publicly available (Hambly et al. 2001MNRAS.326.1279H). The scanning program has now moved on to the northern hemisphere, using film and glass copies of plates taken by the Oschin Schmidt Telescope on Mount Palomar, California. These data will soon be publicly available.
2250. RI photometry of cool dwarfs
ID:
ivo://CDS.VizieR/J/ApJS/94/749
Title:
RI photometry of cool dwarfs
Short Name:
J/ApJS/94/749
Date:
21 Oct 2021
Publisher:
CDS
Description:
The luminosity function at the end of the main sequence is determined from V, R, and I data taken by the CCD/Transit Instrument (CTI), a dedicated telescope surveying an 8.25' wide strip of sky centered at {delta}=+28{deg}, thus sampling Galactic latitudes of +90{deg} down to -35{deg}. A selection of 133 objects chosen via R-I and V-I colors has been observed spectroscopically at the 4.5m Multiple Mirror Telescope to assess contributions by giants and subdwarfs and to verify that the reddest targets are objects of extremely late spectral class. Eighteen dwarfs of type M6 or later have been discovered, with the latest being of type M8.5. Data used for the determination of the luminosity function cover 27.3{deg}^2^ down to a completeness limit of R=19.0.