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331. Berkeley 58 & CG Cas UBV photometry
ID:
ivo://CDS.VizieR/J/MNRAS/388/444
Title:
Berkeley 58 & CG Cas UBV photometry
Short Name:
J/MNRAS/388/444
Date:
21 Oct 2021
Publisher:
CDS
Description:
Photoelectric, photographic and CCD UBV photometry, spectroscopic observations and star counts are presented for the open cluster Berkeley 58 to examine a possible association with the 4.37d Cepheid CG Cas. The cluster is difficult to separate from the early-type stars belonging to the Perseus spiral arm, in which it is located, but has reasonably well-defined parameters: an evolutionary age of ~10^8^yr, a mean reddening of E(B-V)(B0)=0.70+/-0.03 s.e. and a distance of 3.03+/-0.1kpc (V_0_-M_V_=12.40+/-0.12 s.d.). CG Cas is a likely cluster coronal member on the basis of radial velocity, and its period increase of +0.170+/- 0.01s/y and large light amplitude describe a Cepheid in the third crossing of the instability strip lying slightly blueward of strip centre. Its inferred reddening and luminosity are E(B-V)=0.64+/-0.02 s.e. and <M_V_>=-3.06+/-0.12. A possible K supergiant may also be a cluster member.
332. Berkeley 90. III. Cluster parameters
ID:
ivo://CDS.VizieR/J/MNRAS/465/784
Title:
Berkeley 90. III. Cluster parameters
Short Name:
J/MNRAS/465/784
Date:
21 Oct 2021
Publisher:
CDS
Description:
The open cluster Berkeley 90 is the home to one of the most massive binary systems in the Galaxy, LS III +46 11, formed by two identical, very massive stars (O3.5 If* + O3.5 If*), and a second early-O system (LS III +46 12 with an O4.5 IV((f)) component at least). Stars with spectral types earlier than O4 are very scarce in the Milky Way, with no more than 20 examples. The formation of such massive stars is still an open question today, and thus the study of the environments where the most massive stars are found can shed some light on this topic. To this aim, we determine the properties and characterize the population of Berkeley 90 using optical, near-infrared and WISE photometry and optical spectroscopy. This is the first determination of these parameters with accuracy. We find a distance of 3.5+/-0.5kpc and a maximum age of 3Ma. The cluster mass is around 1000M_{sun}_ (perhaps reaching 1500M_{sun}_ if the surrounding population is added), and we do not detect candidate runaway stars in the area. There is a second population of young stars to the Southeast of the cluster that may have formed at the same time or slightly later, with some evidence for low-activity ongoing star formation.
333. Berkeley 93 RVB photometry
ID:
ivo://CDS.VizieR/J/AJ/107/2101
Title:
Berkeley 93 RVB photometry
Short Name:
J/AJ/107/2101
Date:
21 Oct 2021
Publisher:
CDS
Description:
While performing galactic and extragalactic studies near the galactic plane in Cepheus. CCD frames in B, V, and R were taken of the faint (V>=16m), previously unstudied open star cluster Berkeley 93 (Be 93). Our results indicate that this object is the core of a larger aggregate, is slightly evolved, strongly reddened [E(B-V)~1.5], and shows a pronounced variable reddening that is probably due to the location of the cluster inside (near the border) a dust cloud. By far the reddest, and obviously most evolved star is a (variable) carbon star that-because of its reddening and location-appears to be a cluster member. We present arguments in favour of a large distance of more than 5kpc for Be 93 which possibly belongs to the galactic warp. As an addendum, we present six star concentrations discovered on the POSS or ESO/SERC atlas that might represent hitherto uncatalogued open star clusters of "Berkeley type."
334. Berkeley 39 stars photometry and abundances
ID:
ivo://CDS.VizieR/J/A+A/548/A122
Title:
Berkeley 39 stars photometry and abundances
Short Name:
J/A+A/548/A122
Date:
21 Oct 2021
Publisher:
CDS
Description:
The most massive star clusters include several generations of stars with a different chemical composition (mainly revealed by an Na-O anti-correlation) while low-mass star clusters appear to be chemically homogeneous. We are investigating the chemical composition of several clusters with masses of a few 10^4^M_{sun}_ to establish the lower mass limit for the multiple stellar population phenomenon. Using VLT/FLAMES spectra we determine abundances of Fe, O, Na, and several other elements ({alpha} Fe-peak, and neutron-capture elements) in the old open cluster Berkeley 39. This is a massive open cluster: M~10^4^M_{sun}_, approximately at the border between small globular clusters and large open clusters. Our sample size of about 30 stars is one of the largest to be studied for abundances in any open cluster, and could be useful to determine improved cluster parameters, like age, distance, and reddening, when coupled with precise, well-calibrated photometry. We find that Berkeley 39 is slightly metal- poor, <[Fe/H]>~=-0.20, in agreement with previous studies of this cluster. More importantly, we do not detect any star-to-star variation in the abundances of Fe, O, and Na, within quite stringent upper limits. The r.m.s. scatter is of 0.04, 0.10, and 0.05dex for Fe, O, and Na, respectively. Such a small spread can be entirely explained by the noise in the spectra and by uncertainties in the atmospheric parameters. We conclude that Berkeley 39 is a single-population cluster.
335. Berkeley 51 UBV photometry
ID:
ivo://CDS.VizieR/J/MNRAS/477/2976
Title:
Berkeley 51 UBV photometry
Short Name:
J/MNRAS/477/2976
Date:
02 Mar 2022 00:35:30
Publisher:
CDS
Description:
The heavily obscured open cluster Berkeley 51 shows characteristics typical of young massive clusters, even though the few previous studies have suggested older ages. We combine optical (UBV) and 2MASS photometry of the cluster field with multi-object and long-slit optical spectroscopy for a large sample of stars. We apply classical photometric analysis techniques to determine the reddening to the cluster, and then derive cluster parameters via isochrone fitting. We find a large population of B-type stars, with a main-sequence turn-off at B3 V, as well as a large number of supergiants with spectral types ranging from F to M. We use intermediate-resolution spectra of the evolved cool stars to derive their stellar parameters and find an essentially solar iron abundance. Under the plausible assumption that our photometry reaches stars still close to the zero-age main sequence, the cluster is located at d=~5.5kpc and has an age of ~60Ma, though a slightly younger and more distant cluster cannot be ruled out. Despite the apparent good fit of isochrones, evolved stars seem to reside in positions of the colour-magnitude diagram far away from the locations where stellar tracks predict helium burning to occur. Of particular interest is the presence of four yellow supergiants, two on the ascending branch and two others close to or inside the instability strip.
336. Be stars in MC star clusters NIR properties
ID:
ivo://CDS.VizieR/J/other/NewA/56.28
Title:
Be stars in MC star clusters NIR properties
Short Name:
J/other/NewA/56.
Date:
21 Oct 2021
Publisher:
CDS
Description:
Magellanic Clouds are the nearby galaxies which are ideal to study the properties of metal poor stellar population. In this study, we explore the near-IR properties of optically identified classical Be stars in 19 star clusters in the Magellanic Clouds. From an optically identified sample of 835 Be stars we obtained the J, H, K magnitudes of 389 stars from the IRSF MCPS catalog. Among these, 247 stars (36.4%) are found in 9 clusters in the Large Magellanic Cloud and 142 stars (55.5%) in 10 clusters in the Small Magellanic Cloud. After correcting for reddening, we studied their NIR properties in the (H-K)_0_ vs (J-H)_0_ diagram. We identified 14 stars with abnormally large near IR excesses, which were removed from the analysis, there by restricting our study to 355 classical Be stars. We propose an extended area in the near-IR (H-K)_0_ vs (J-H)_0_ diagram as the diagnostic location of Classical Be stars in the Magellanic Clouds. We identified 14 stars to have near-IR excess, higher than those seen in classical Be stars. From the analysis based on spectral energy distribution and luminosity estimate, we found that 8 candidate Be stars may be Herbig Ae/Be stars. We identified a new sample of 6 sgB[e] stars, which when added to the sparse existing sample of 15 sgB[e] stars in the Magellanic Clouds can provide insight to understand the evolutionary link between sgB[e] stars and Luminous Blue variables.
337. Be stars in MC young clusters
ID:
ivo://CDS.VizieR/J/A+AS/134/489
Title:
Be stars in MC young clusters
Short Name:
J/A+AS/134/489
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results of a search for Be stars in six fields centered on the young clusters NGC 330 and NGC 346 in the SMC, and NGC 1818, NGC 1948, NGC 2004 and NGC 2100 in the LMC. Be stars were identified by differencing R band and narrow-band H{alpha} CCD images. Our comparatively large images provide substantial Be star populations both within the clusters and in their surrounding fields. Magnitudes, positions and finding charts are given for the 224 Be stars found. The fraction of Be stars to normal B stars within each cluster is found to vary significantly although the average ratio is similar to the average Be to B star ratio found in the Galaxy. In some clusters, the Be star population is weighted to magnitudes near the main sequence turn-off. The Be stars are redder in V-I than normal main-sequence stars of similar magnitude and the redness increases with increasing H{alpha} emission strength.
338. Be stars in open clusters with PTF/iPTF. I.
ID:
ivo://CDS.VizieR/J/AJ/155/91
Title:
Be stars in open clusters with PTF/iPTF. I.
Short Name:
J/AJ/155/91
Date:
21 Oct 2021
Publisher:
CDS
Description:
We conducted a search for Be star candidates in open clusters using H{alpha} imaging photometry of the Palomar Transient Factory Survey to investigate some connections among Be star phenomena, cluster environments, and ages. Stellar members of clusters were identified by spatial distributions, near-infrared magnitudes and colors, and by proper motions. Among 104 open clusters, we identified 96 Be star candidates in 32 clusters; 11 of our candidates have been reported in previous studies. We found that the clusters with age 7.5<log(t(year))=<8.5 tend to have more Be star candidates; there is about a 40% occurrence rate within this age bin. The clusters in this age bin also tend to have a higher Be fraction N(Be)/N(Be+B-type). These results suggest that the environments of young and intermediate clusters are favorable to the formation of Be phenomena. Spatial distribution of Be star candidates with different ages implies that they do not form preferentially in the central regions. Furthermore, we showed that the mid-infrared (MIR) colors of the Be star candidates are similar to known Be stars, which could be caused by free-free emission or bound-free emission. Some Be star candidates might have no circumstellar dust according to their MIR colors. Finally, among 96 Be candidates, we discovered that one Be star candidate FSR 0904-1 exhibits long-term variability on the timescale of ~2000 days with an amplitude of 0.2-0.3 mag, indicating a long timescale of disk evolution.
339. BEST-II catalog of variables: CoRoT SRc02 field
ID:
ivo://CDS.VizieR/J/AJ/151/110
Title:
BEST-II catalog of variables: CoRoT SRc02 field
Short Name:
J/AJ/151/110
Date:
21 Oct 2021
Publisher:
CDS
Description:
Time-series photometry of the CoRoT field SRc02 was obtained by the Berlin Exoplanet Search Telescope II (BEST II) in 2009. The main aim was to conduct a ground-based follow-up of the CoRoT field in order to detect variable stars with better spatial resolution than what can be achieved with the CoRoT Space Telescope. A total of 1846 variable stars were detected, of which only 30 have been previously known. For nine eclipsing binaries the stellar parameters were determined by modeling their light curves.
340. BEST-II catalog of variables. III. Puppis field
ID:
ivo://CDS.VizieR/J/AJ/156/204
Title:
BEST-II catalog of variables. III. Puppis field
Short Name:
J/AJ/156/204
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Berlin Exoplanet Search Telescope II (BEST II) is a ground-based, small aperture, wide-angle telescope used to search for stellar light variations in the southern hemisphere. We report the results of a monitoring campaign observing a field in the Puppis constellation in late 2011/early 2012. Light curves were obtained for 130472 stars, out of which we identify 2169 variables, including 1829 newly discovered, 26 previously known, and 314 suspected variable stars. We determine periods and variability class for two previously known, but only suspected to be, variable stars. For eight individual eclipsing binary stars, including the two previously known but unclassified binaries, the system parameters were derived at the epoch of the observation by modeling the light curves. Eventually, in a catalog for all variable stars, we present coordinates, magnitude, and elements of light variations, e.g., epoch, period, amplitude, type, and light curves. This catalog concludes the BEST/BEST II project.