- 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.
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Search Results
- ID:
- ivo://CDS.VizieR/VIII/11
- Title:
- Berkeley Low-Latitude H I Survey
- Short Name:
- VIII/11
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This survey consists of H I 21-cm spectra covering galactic latitudes from -10 degrees to +10 degrees and galactic longitudes from 10degrees to 250degrees. The observations were made with the Hat Creek 85-foot telescope between 1968 and 1970. The individual spectra contain 238 points per profile spaced every 5kHz and cover a velocity range of 250km/s. The velocity resolution is 2km/s (half-power of each filter) and the half-power beamwidth is 35arcmin. The spacing between points observed on the sky are 0.25degrees in galactic latitude and 0.5degrees in galactic longitude. Each spectrum or record consists of a header followed by 238 antenna temperatures. The header contains the galactic longitude, galactic latitude, and central velocity (LSR). The catalog contains a total of 38961 spectra.
- 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."
- 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.
- ID:
- ivo://CDS.VizieR/J/MNRAS/425/1789
- Title:
- Berkeley supernova Ia program. I.
- Short Name:
- J/MNRAS/425/1789
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this first paper in a series, we present 1298 low-redshift (z<~0.2) optical spectra of 582 Type Ia supernovae (SNe Ia) observed from 1989 to 2008 as part of the Berkeley Supernova Ia Program (BSNIP). 584 spectra of 199 SNe Ia have well-calibrated light curves with measured distance moduli, and many of the spectra have been corrected for host-galaxy contamination. Most of the data were obtained using the Kast double spectrograph mounted on the Shane 3m telescope at Lick Observatory and have a typical wavelength range of 3300-10400{AA}, roughly twice as wide as spectra from most previously published data sets. We present our observing and reduction procedures, and we describe the resulting SN Database, which will be an online, public, searchable data base containing all of our fully reduced spectra and companion photometry. In addition, we discuss our spectral classification scheme (using the SuperNova IDentification code, SNID; Blondin & Tonry, 2007ApJ...666.1024B), utilizing our newly constructed set of SNID spectral templates.
- ID:
- ivo://CDS.VizieR/J/MNRAS/425/1819
- Title:
- Berkeley supernova Ia program. II.
- Short Name:
- J/MNRAS/425/1819
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this second paper in a series, we present measurements of spectral features of 432 low-redshift (z<0.1) optical spectra of 261 Type Ia supernovae (SNe Ia) within 20d of maximum brightness. The data were obtained from 1989 to the end of 2008 as part of the Berkeley Supernova Ia Program (BSNIP) and are presented in BSNIP I by Silverman et al. (J/MNRAS/425/1789). We describe in detail our method of automated, robust spectral feature definition and measurement which expands upon similar previous studies. Using this procedure, we attempt to measure expansion velocities, pseudo-equivalent widths (pEWs), spectral feature depths and fluxes at the centre and endpoints of each of nine major spectral feature complexes.
- 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.
- ID:
- ivo://CDS.VizieR/J/MNRAS/474/5287
- Title:
- BeSOS Be stars stellar parameters
- Short Name:
- J/MNRAS/474/5287
- Date:
- 07 Dec 2021 13:16:10
- Publisher:
- CDS
- Description:
- The Be phenomenon is present in about 20 per cent of B-type stars. Be stars show variability on a broad range of time-scales, which in most cases is related to the presence of a circumstellar disc of variable size and structure. For this reason, a time-resolved survey is highly desirable in order to understand the mechanisms of disc formation, which are still poorly understood. In addition, a complete observational sample would improve the statistical significance of the study of stellar and disc parameters. The 'Be Stars Observation Survey' (BeSOS) is a survey containing reduced spectra obtained using the Pontifica Universidad Catolica High Echelle Resolution Optical Spectrograph (PUCHEROS) with a spectral resolution of 17000 in the range 4260-7300{AA}. BeSOS's main objective is to offer consistent spectroscopic and time-resolved data obtained with one instrument. The user can download or plot the data and obtain stellar parameters directly from the website. We also provide a star-by-star analysis based on photometric, spectroscopic and interferometric data, as well as general information about the whole BeSOS sample. Recently, BeSOS led to the discovery of a new Be star HD 42167 and facilitated study of the V/R variation of HD 35165 and HD 120324, the steady disc of HD 110335 and the Be shell status of HD 127972. Optical spectra used in this work, as well as the stellar parameters derived, are available online at http://besos.ifa.uv.cl.
- ID:
- ivo://CDS.VizieR/J/AN/331/852
- Title:
- Bessel (1825) calculation for geodesic measurements
- Short Name:
- J/AN/331/852
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This is an English translation of F.W. Bessel's paper on geodesics which appeared as "Ueber die Berechnung der geographischen Laengen und Breiten aus geodaetischen Vermessungen", Astronomische Nachrichten 4(86), 241-254 (1825), 1825AN......4..241B.
- ID:
- ivo://CDS.VizieR/J/MNRAS/469/4175
- Title:
- Be star candidates in Magellanic Clouds
- Short Name:
- J/MNRAS/469/4175
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a proper motion investigation of a sample of Be star candidates towards the Magellanic Clouds, which has resulted in the identification of separate populations, in the Galactic foreground and in the Magellanic background. Be stars are broadly speaking B-type stars that have shown emission lines in their spectra. In this work, we studied a sample of 2446 and 1019 Be star candidates towards the Large Magellanic Cloud (LMC) and Small Magellanic Cloud (SMC), respectively, taken from the literature and proposed as possible Be stars due to their variability behaviour in the OGLE-II I band. JHKs magnitudes from the InfraRed Survey Facility catalogue and proper motions from the Southern Proper Motion 4 catalogue were obtained for 1188 and 619 LMC and SMC Be stars candidates, respectively. Colour-colour and vector-point diagrams were used to identify different populations amongst the Be star candidates. In the LMC sample, two populations with distinctive infrared colours and kinematics were found, the bluer sample is consistent with being in the LMC and the redder one with belonging to the Milky Way disc. This settles the nature of the redder sample that had been described in previous publications as a possible unknown subclass of stars amongst the Be candidates in the LMC. In the SMC sample, a similar but less evident result was obtained, since this apparent unknown subclass was not seen in this galaxy. We confirm that in the selection of Be stars by their variability, although generally successful, there is a higher risk of contamination by Milky Way objects towards redder B-V and V-I colours.