- ID:
- ivo://CDS.VizieR/J/A+A/325/167
- Title:
- Geneva photometry in NGC 6231
- Short Name:
- J/A+A/325/167
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present photoelectric (127 stars) and CCD (168 stars) Geneva photometry for the very young open cluster NGC 6231. We have searched for new cluster members out to a distance of ~13arcmin, extending the Seggewiss area (~8arcmin), and we found at least 64 new probable members in this extended field. Differential reddening is clearly measured across the cluster area. We determine the cluster distance (1800pc) and age (3.8+/-0.6x10^6^yr). The probable presence of pre-main sequence stars and the consequence of this population on the cluster formation history is analysed. We also found that the O8.5III star S161 is a long term variable and we present its light curve extending over more than 20 years. Finally we discuss the existence of Ap stars in the cluster. For a description of the Geneva photometric system, see e.g. <GCPD/13>
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Search Results
- ID:
- ivo://CDS.VizieR/J/AZh/88/954
- Title:
- Geometry of radio pulsar magnetospheres
- Short Name:
- J/AZh/88/954
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Data on the profiles and polarization of the 10- and 20-cm emission of radio pulsars are used to calculate the angle {beta} between the rotational axis of the neutron star and its magnetic moment. It is shown that, for these calculations, it is sufficient to use catalog values of the pulse width at the 10% level W10, since the broadening of the observed pulses due to the transition to the full width W0 and narrowing of the pulses associated with the emission of radiation along tangents to the field lines approximately cancel each other out. The angles {beta}1 are calculated for 283 pulsars at 20cm and 132 pulsars at 10cm, assuming that the line of sight passes through the center of the emission cone.
5403. GEOS RR Lyr survey
- ID:
- ivo://CDS.VizieR/J/other/IBVS/5767
- Title:
- GEOS RR Lyr survey
- Short Name:
- J/other/IBVS/576
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present here the sixth list of light maxima of RR Lyrae stars from the GEOS RR Lyr Survey, a GEOS program (http://www.upv.es/geos/) (Boninsegna et al., 2002ASPC..259..166B) of automated observations of RR Lyr stars started in January 2004.
- ID:
- ivo://CDS.VizieR/II/55
- Title:
- Gershberg Flare Star Catalogue
- Short Name:
- II/55
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This catalog groups the flare stars as presented in the IAU Colloquium 15 (combined Colloquium of Commisions 27 and 42) held at Bamberg 31-Aug to 03-Sep 1971 entitled "New Directions and New Frontiers in Variable Star Research" The following definition of the UV Cet-type variables was given in Kukarkin's General Catalogue of Variable Stars (1969): "dMe stars, sometimes subject to flares with the amplitude from 1 to 6mag. Maximum brightness is attained in seconds or dozens of seconds after the commencement of the flare; the star returns to its normal brightness after several minutes, or dozens of minutes. A typical representative is UV Ceti." Now it is impossible to consider this definition as a quite right because: 1) There are a number of M-dwarf stars affected by the flares similar to the UV Ceti flares, but in their quiet state spectra, no emission lines are observed. For example, BD+43 44A, BD+43 44 B, and SZ UMa, the flare activity of these stars were detected in Crimea; and probably BD-04 4048B is suspected as a flare star by HERBIG. 2) The lower limit of flare amplitude cited in Kukarkin's corresponds to visual observations, but the modern photoelectric observations register flares with amplitudes to 0.02-0.05mag. Therefore we suppose, that UV Cet-type variables are K-M dwarfs, which show quick flares with amplitudes exceeding the observational errors, and duration of the flares are from a few seconds up to a few hundred minutes. The "catalog" file includes only such variable K-M dwarf stars, for which existing observations allow to construct flare light curves. All stars in "catalog", except V371 Ori, have photoelectric flare light curves. The strong flare of V371 Ori was observed in radio region, but simultaneous optical observations were carried out photographically and visually only.
- ID:
- ivo://CDS.VizieR/J/A+A/601/A112
- Title:
- GES iDR4 Mg-Al anticorrelation in GCs
- Short Name:
- J/A+A/601/A112
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use Gaia-ESO Survey iDR4 data to explore the Mg-Al anti-correlation in globular clusters, that were observed as calibrators, as a demonstration of the quality of Gaia-ESO Survey data and analysis. The results compare well with the available literature, within 0.1~[-] or less, after a small (compared to the Minternal spreads) offset between the UVES and the GIRAFFE data of 0.10-0.15dex was taken into account. In particular, we present for the first time data for NGC 5927, one of the most metal-rich globular clusters studied in the literature so far with [Fe/H]=-0.49dex, that was included to connect with the open cluster regime in the Gaia-ESO Survey internal calibration. The extent and shape of the Mg-Al anti-correlation provide strong constraints on the multiple population phenomenon in globular clusters. In particular, we studied the dependency of the Mg-Al anti-correlation extension with metallicity, present-day mass, and age of the clusters, using GES data in combination with a large set of homogenized literature measurements. We find a dependency with both metallicity and mass, that is evident when fitting for the two parameters simultaneously, but no significant dependency with age. We confirm that the Mg-Al anti-correlation is not seen in all clusters, but disappears for the less massive or most metal-rich ones. We also use our dataset to see whether a normal anti-correlation would explain the low [Mg/{alpha}] observed in some extragalactic globular clusters, but find that none of the clusters in our sample can reproduce it, and more extreme chemical compositions (like the one of NGC 2419) would be required. We conclude that GES iDR4 data already meet the requirements set by the main survey goals, and can be used to study in detail globular clusters even if the analysis procedures were not specifically designed for them.
- ID:
- ivo://CDS.VizieR/J/A+A/608/A95
- Title:
- GES: multi-line spectroscopic binary candidates
- Short Name:
- J/A+A/608/A95
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Gaia-ESO Survey (GES) is a large spectroscopic survey that provides a unique opportunity to study the distribution of spectroscopic multiple systems among different populations of the Galaxy. Aims. Our aim is to detect binarity/multiplicity for stars targeted by the GES from the analysis of the cross-correlation functions (CCFs) of the GES spectra with spectral templates. We developed a method based on the computation of the CCF successive derivatives to detect multiple peaks and determine their radial velocities, even when the peaks are strongly blended. The parameters of the detection of extrema (DOE) code have been optimized for each GES GIRAFFE and UVES setup to maximize detection. The DOE code therefore allows to automatically detect multiple line spectroscopic binaries (SBn, n>=2). We apply this method on the fourth GES internal data release and detect 354 SBn candidates (342 SB2, 11 SB3, and even one SB4), including only nine SBs known in the literature. This implies that about 98% of these SBn candidates are new because of their faint visual magnitude that can reach V=19. Visual inspection of the SBn candidate spectra reveals that the most probable candidates have indeed a composite spectrum. Among the SB2 candidates, an orbital solution could be computed for two previously unknown binaries: CNAME 06404608+0949173 (known as V642 Mon) in NGC 2264 and CNAME 19013257-0027338 in Berkeley 81 (Be 81). A detailed analysis of the unique SB4 (four peaks in the CCF) reveals that CNAME 08414659-5303449 (HD 74438) in the open cluster IC 2391 is a physically bound stellar quadruple system. The SB candidates belonging to stellar clusters are reviewed in detail to discard false detections. We suggest that atmospheric parameters should not be used for these system components; SB-specific pipelines should be used instead. Our implementation of an automatic detection of spectroscopic binaries within the GES has allowed the efficient discovery of many new multiple systems. With the detection of the SB1 candidates that will be the subject of a forthcoming paper, the study of the statistical and physical properties of the spectroscopic multiple systems will soon be possible for the entire GES sample.
- ID:
- ivo://CDS.VizieR/J/A+A/618/A102
- Title:
- GES N/O abundance ratio in the Milky Way
- Short Name:
- J/A+A/618/A102
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The abundance ratio N/O is a useful tool to study the interplay of galactic processes, for example star formation efficiency, timescale of infall, and outflow loading factor. We aim to trace log(N/O) versus [Fe/H] in the Milky Way and to compare this ratio with a set of chemical evolution models to understand the role of infall, outflow, and star formation efficiency in the building up of the Galactic disc. We used the abundances from idr2-3, idr4, idr5 data releases of the Gaia-ESO Survey both for Galactic field and open cluster stars. We determined membership and average composition of open clusters and we separated thin and thick disc field stars. We considered the effect of mixing in the abundance of N in giant stars. We computed a grid of chemical evolution models, suited to reproduce the main features of our Galaxy, exploring the effects of the star formation efficiency, infall timescale, and differential outflow. With our samples, we map the metallicity range -0.6<=[Fe/H]<=0.3 with a corresponding -1.2<=log(N/O)<=-0.2, where the secondary production of N dominates. Thanks to the wide range of Galactocentric distances covered by our samples, we can distinguish the behaviour of log(N/O) in different parts of the Galaxy. Our spatially resolved results allow us to distinguish differences in the evolution of N/O with Galactocentric radius. Comparing the data with our models, we can characterise the radial regions of our Galaxy. A shorter infall timescale is needed in the inner regions, while the outer regions need a longer infall timescale, coupled with a higher star formation efficiency. We compare our results with nebular abundances obtained in MaNGA galaxies, finding in our Galaxy a much wider range of log(N/O) than in integrated observations of external galaxies of similar stellar mass, but similar to the ranges found in studies of individual HII regions.
- ID:
- ivo://CDS.VizieR/J/A+A/601/A70
- Title:
- GES: pre-main-sequence clusters [Fe/H]
- Short Name:
- J/A+A/601/A70
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The radial metallicity distribution in the Galactic thin disc represents a crucial constraint for modelling disc formation and evolution. Open clusters allow us to derive both the radial metallicity distribution and its evolution over time. In this paper we perform the first investigation of the present-day radial metallicity distribution based on [Fe/H] determinations in late type members of pre-main-sequence clusters. Because of their youth, these clusters are therefore essential for tracing the current inter-stellar medium metallicity. We used the products of the Gaia-ESO Survey analysis of 12 young regions (age<100Myr), covering Galactocentric distances from 6.67 to 8.70kpc. For the first time, we derived the metal content of star forming regions farther than 500pc from the Sun. Median metallicities were determined through samples of reliable cluster members. For ten clusters the membership analysis is discussed in the present paper, while for other two clusters (Chamaeleon I and Gamma Velorum) we adopted the members identified in our previous works. All the pre-main-sequence clusters considered in this paper have close-to-solar or slightly sub-solar metallicities. The radial metallicity distribution traced by these clusters is almost flat, with the innermost star forming regions having [Fe/H] values that are 0.10-0.15dex lower than the majority of the older clusters located at similar Galactocentric radii. This homogeneous study of the present-day radial metallicity distribution in the Galactic thin disc favours models that predict a flattening of the radial gradient over time. On the other hand, the decrease of the average [Fe/H] at young ages is not easily explained by the models. Our results reveal a complex interplay of several processes (e.g. star formation activity, initial mass function, supernova yields, gas flows) that controlled the recent evolution of the Milky Way.
- ID:
- ivo://CDS.VizieR/J/ApJ/794/82
- Title:
- GeV gamma-ray bursts with the ARGO-YBJ detector
- Short Name:
- J/ApJ/794/82
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The search for gamma-ray burst (GRB) emission in the energy range of 1-100 GeV in coincidence with the satellite detection has been carried out using the Astrophysical Radiation with Ground-based Observatory at YangBaJing (ARGO-YBJ) experiment. The high-altitude location (4300 m a.s.l.), the large active surface (~6700 m^2^ of Resistive Plate Chambers), the wide field of view (~2 sr, limited only by the atmospheric absorption), and the high duty cycle (>86%) make the ARGO-YBJ experiment particularly suitable to detect short and unexpected events like GRBs. With the scaler mode technique, i.e., counting all the particles hitting the detector with no measurement of the primary energy and arrival direction, the minimum threshold of ~1 GeV can be reached, overlapping the direct measurements carried out by satellites. During the experiment lifetime from 2004 December 17 to 2013 February 7, a total of 206 GRBs occurring within the ARGO-YBJ field of view (zenith angle {theta}<=45{deg}) have been analyzed. This is the largest sample of GRBs investigated with a ground-based detector. Two light curve models have been assumed and since in both cases no significant excess has been found, the corresponding fluence upper limits in the 1-100 GeV energy region have been derived, with values as low as 10^-5^ erg/cm2. The analysis of a subset of 24 GRBs with known redshift has been used to constrain the fluence extrapolation to the GeV region together with possible cutoffs under different assumptions on the spectrum.
- ID:
- ivo://CDS.VizieR/J/A+A/656/A101
- Title:
- G305 Giant Molecular Cloud II. Clump properties
- Short Name:
- J/A+A/656/A101
- Date:
- 21 Mar 2022 07:03:46
- Publisher:
- CDS
- Description:
- G305 star-forming complex was observed in the 3-2 lines of 12 & 13CO to investigate the effect of feedback from the central OB stars on the complex. The region was decomposed into clumps using dendrogram analysis. A catalog of clump properties was created. The surface mass densities of the clumps were plotted as a function of the incident 8um flux. A mask of the region with 8um flux >100MJy/sr was created and clumps were categorized based on the extent of overlap with the mask into "mostly inside", "partly inside" & "outside". The surface mass density distribution of each of these populations were plotted. This was followed by comparing G305 clumps with the Galactic average taken from the ATLASGAL and CHIMPS clumps. Finally, the cumulative distribution functions (CDF) of the clump masses in G305 & their L/M ratios were compared to that of the Galactic sample. The surface mass densities of clumps showed a positive correlation with incident 8um flux. The data did not have sufficient velocity resolution to discern the effects of feedback on the linewidths of the clumps. The sub-sample of clumps named "mostly inside" had the highest surface mass densities followed by "partly -inside" and "outside" sub-samples. These differences between the three sub-samples were shown to be statistically significant using the KS test. The "mostly inside" sample also showed the highest level of fragmentation compared to the other two. These prove that clumps inside the G305 region are triggered. The G305 clump population is also statistically different from the Galactic average population rejecting redistribution as a likely consequence of feedback. The CDFs of clump masses and their L/M ratios are both flatter than the Galactic average, indicating that feedback in G305 has triggered star formation. The collect & collapse method is the dominant mechanism at play in G305.