- ID:
- ivo://CDS.VizieR/J/A+A/601/A56
- Title:
- NGC 6802 dwarf cluster members and non-members
- Short Name:
- J/A+A/601/A56
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Milky Way open clusters are very diverse in terms of age, chemical composition, and kinematic properties. Intermediate-age and old open clusters are less common, and it is even harder to find them inside the solar Galactocentric radius, due to the high mortality rate and strong extinction inside this region. NGC 6802 is one of the inner disk open clusters (IOCs) observed by the $Gaia$-ESO survey (GES). This cluster is an important target for calibrating the abundances derived in the survey due to the kinematic and chemical homogeneity of the cluster members in open clusters. Using the measurements from $Gaia$-ESO internal data release 4 (iDR4), we identify 95 dwarf main-sequence stars as cluster members from the GIRAFFE target list, and 8 red giants as cluster members from the UVES target list. The dwarf cluster members have a median radial velocity of 13.6+/-1.9km/s, while the giant cluster members have a median radial velocity of 12.0+/-0.9km/s and a median [Fe/H] of 0.10+/-0.02dex. The color-magnitude diagram of these cluster members suggests an age of $0.9+/-0.1Gyr, with (m-M)_0_=11.4 and E(B-V)=0.86. We perform the first chemical abundance analysis of NGC 6802, including 27 element species. To gain a more general picture about IOCs, the measurements of NGC6802 are compared with those of other IOCs previously studied by GES, i.e., NGC 4815, Trumpler 20, NGC 6705, and Berkeley 81. NGC 6802 shows similar C, N, Na, and Al abundances as other IOCs. The abundance versus cluster turn-off mass for these elements in the five GES IOCs cannot firmly exclude any one of the competing nucleosynthetic models, including: standard models; models with rotation induced mixing and/or thermohaline mixing. The five GES IOCs, particularly NGC 6802, seem to have higher s-process element abundances than that of the inner disk field stars.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/133/44
- Title:
- NGC 346 HST VI photometry
- Short Name:
- J/AJ/133/44
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In the quest to understand how star formation occurs and propagates in the low-metallicity environment of the Small Magellanic Cloud (SMC), we acquired deep F555W (~V) and F814W (~I) Hubble Space Telescope ACS images of the young and massive star-forming region NGC 346. These images and their photometric analysis provide us with a snapshot of the star formation history of the region. We find evidence for star formation extending from ~10Gyr in the past until ~150Myr in the field of the SMC. The youngest stellar population (~3+/-1Myr) is associated with the NGC 346 cluster. It includes a rich component of low-mass pre-main-sequence stars mainly concentrated in a number of subclusters spatially colocated with CO clumps previously detected by Rubio and coworkers. Within our analysis uncertainties, these subclusters appear coeval with each other.
- ID:
- ivo://CDS.VizieR/J/MNRAS/420/2884
- Title:
- NGC 1960 IRAC and MIPS photometry
- Short Name:
- J/MNRAS/420/2884
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an analysis of Spitzer IRAC (3.6-8um) and MIPS (24um) imaging of members of the 16^+10^_-5_ Myr old open cluster NGC 1960 (M36). Models of terrestrial planet formation indicate that rocky planets are likely to achieve their final masses at around 10-30Myr, and thus this cluster is at an interesting epoch for planet formation. We find 21 B-F5 type stars and 14 F6-K9 type stars which have 24um excess emission, and thus determine that >30 per cent of B-F5 type stars and >23 per cent of F6-K9 type stars in this cluster have 24um excess emission. These excess frequencies are similar to those observed in other clusters of similar age. Three early-type stars have excesses at near-infrared wavelengths. Analysis of their spectral energy distributions confirms that these are true debris discs and not remnant primordial or transitional discs. None of the 61 Sun-like stars has confirmed near-infrared excess, and we can place a limit on the frequency of 8um excess emission around Sun-like stars of <7 per cent. All of the detected excesses are consistent with emission from debris discs and are not primordial.
- ID:
- ivo://CDS.VizieR/J/A+A/641/A51
- Title:
- NGC 2516 membership list
- Short Name:
- J/A+A/641/A51
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We wish to measure the cool star rotation period distribution for the Pleiades-age rich open cluster NGC 2516 and use it to determine whether cluster-to-cluster variations exist in otherwise identical open clusters. We obtained 42d-long time-series CCD photometry of NGC 2516 in the V and Ic filters using the Yale 1m telescope at CTIO and performed a number of related analyses, including PSF-based time-series photometry. Our data are complemented with additional information from several photometric datasets, literature radial velocities, and Gaia DR2 astrometry. All available data are used to construct an integrated membership list for NGC 2516, containing 844 stars in our ~1 degree field of view. We derived 308 rotation periods for late-F to mid-M cluster members from our photometry. We identified an additional 247 periodic M dwarf stars from a prior study as cluster members, and used these to construct a 555-star rotation period distribution for NGC 2516. The colour-period diagram (in multiple colours) has almost no outliers and exhibits the anticipated triangular shape, with a diagonal slow rotator sequence that is preferentially occupied by the warmer stars along with a flat fast rotator sequence that is preferentially populated by the cooler cluster members. We also find a group of extremely slowly rotating M dwarfs (10d<P<23d), forming a branch in the colour-period diagram which we call the 'extended slow rotator sequence'. This, and other features of the rotational distribution can also be found in the Pleiades, making the colour-period diagrams of the two clusters nearly indistinguishable. A comparison with the well-studied (and similarly aged) open cluster M 35 indicates that the cluster's rotational distribution is also similarly indistinguishable from that of NGC 2516. Those for the open clusters M 50 and Blanco 1 are similar, but data issues for those clusters make the comparisons somewhat more ambiguous. Nevertheless, we demonstrate the existence of a representative zero-age main sequence (ZAMS) rotational distribution and provide a simple colour-independent way to represent it. We perform a detailed comparison of the NGC 2516 rotation period data with a number of recent rotational evolution models. Using X-ray data from the literature, we also construct the first rotation-activity diagram for solar-type stars in NGC 2516, one that we find is essentially indistinguishable from those for the Pleiades and Blanco 1. The two clusters NGC 2516 and Pleiades can be considered twins in terms of stellar rotation and related properties (and M 35, M 50, and Blanco 1 are similar), suggesting that otherwise identical open clusters also have intrinsically similar cool star rotation and activity distributions.
- ID:
- ivo://CDS.VizieR/J/A+A/337/125
- Title:
- NGC 1750 & 1758 membership probabilities
- Short Name:
- J/A+A/337/125
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Cluster-field segregation and determination of physical parameters of the open clusters NGC 1750 and NGC 1758 were performed from CCD and photographic photometric and astrometric surveys previously published by the authors. Membership probabilities were computed to a brightness limit of R=15mag through a non-standard method in a fully non-parametric approach, using proper motions, positions and photometry. This study allowed several parameters for NGC 1750 and NGC 1758 to be determined, including position, size, density profile, absorption, distance, age, luminosity function and mass. The common colour excess of both clusters is E(B-V)=0.34mag. NGC 1750 is slightly younger (log(t)=8.3), closer (V-M_v_=9.0mag) and less concentrated than NGC 1758 (log(t)=8.60 and V-M_v_=9.4mag). We also conclude that NGC 1746 is an erroneous assignation (not corresponding to any real open cluster), and that NGC 1750 and NGC 1758 are overlapping clusters, but they do not constitute a gravitationally bounded system.
- ID:
- ivo://CDS.VizieR/J/MNRAS/430/1433
- Title:
- NGC 2264 members periods with CoRoT
- Short Name:
- J/MNRAS/430/1433
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Rotation is one of the key stellar parameters which undergo substantial evolution during the stellar lifetime, in particular during the early stages. Stellar rotational periods can be determined on the basis of the periodic modulation of starlight produced by non-uniformities on the surface of the stars, due to manifestation of stellar activity. We present the results of an extensive search for rotational periods among NGC 2264 cluster members, based on photometric monitoring using the COnvection ROtation and planetary Transits (CoRoT) satellite, with particular attention to the distribution of classical and weak-line T-Tauri stars. NGC 2264 is one of the nearest and best studied star forming region in the solar neighbourhood, with an estimated age of 3Myr, and is the object of a recent simultaneous multiband campaign including a new CoRoT observation with the aim to assess the physical origin of the observed variability. We find that the rotational distributions of classical and weak-line T-Tauri stars are different, suggesting a difference in the rotational properties of accreting and non-accreting stars.
- ID:
- ivo://CDS.VizieR/J/A+AS/123/63
- Title:
- NGC 6530 multiwavelength photometry
- Short Name:
- J/A+AS/123/63
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The distance and formation history of the very young open cluster NGC 6530 were investigated by studying a total of 132 probable member stars of this open cluster. It was concluded that the distance to NGC 6530 is 1.8+/-0.2kpc, and its interstellar reddening E(B-V) is 0.30. Furthermore, we conclude that the extinction law of the intracluster material is normal (i.e. R_V=3.1), but anomalous extinction laws were found for several more embedded stars in the cluster. Of the 132 stars included in this study, 11 are suspected to be variable, five show Halpha in emission and nine show an infrared excess. Among the member stars of NGC 6530, three were found to be part of the Herbig Ae/Be stellar class, whereas two others are possible members of this stellar group as well. Also, one cluster member is probably a new massive post-AGB star, whereas the same could possibly apply to another member star. Finally, from the distribution of post- and pre-main sequence stars in the cluster's HR-diagram, it was concluded that the process of star formation in NGC 6530 must have started a few times 10^7 years ago and, for the less massive stars, is probably still going on today.
- ID:
- ivo://CDS.VizieR/J/A+A/586/A52
- Title:
- NGC 2264, NGC 2547 and NGC 2516 stellar radii
- Short Name:
- J/A+A/586/A52
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Rapidly rotating, low-mass members of eclipsing binary systems have measured radii that are significantly larger than predicted by standard evolutionary models. It has been proposed that magnetic activity is responsible for this radius inflation. By estimating the radii of low-mass stars in three young clusters (NGC 2264, NGC 2547, NGC 2516, with ages of ~5, ~35 and ~140Myr respectively), we aim to establish whether similar radius inflation is seen in single, magnetically active stars. We use radial velocities from the Gaia-ESO Survey (GES) and published photometry to establish cluster membership and then combine GES measurements of projected equatorial velocities with published rotation periods to estimate the average radii for groups of fast-rotating cluster members as a function of their luminosity and age. The average radii are compared with the predictions of both standard evolutionary models and variants that include magnetic inhibition of convection and starspots.
- ID:
- ivo://CDS.VizieR/J/A+AS/131/239
- Title:
- NGC 1750 + NGC 1758 BVR photometry
- Short Name:
- J/A+AS/131/239
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Photographic astrometric and photometric catalogue. Table 6 contains (x,y) positions, (mu_x, mu_y) relative proper motions and BVR photographic photometry. Notes give cross-identifications with other catalogues. Table 11 contains equatorial positions (alpha, delta) and absolute proper motions (mu_alpha cos delta, mu_delta) in FK5 and ICRS reference systems.
- ID:
- ivo://CDS.VizieR/J/MNRAS/465/2820
- Title:
- NGC 6951 & NGC 1512 clusters HST photometry
- Short Name:
- J/MNRAS/465/2820
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyse the cluster luminosity functions (CLFs) of the youngest star clusters in two galaxies exhibiting prominent circumnuclear starburst rings. We focus specifically on NGC 1512 and NGC 6951, for which we have access to H{alpha} data that allow us to unambiguously identify the youngest sample clusters. To place our results on a firm statistical footing, we first explore in detail a number of important technical issues affecting the process from converting the observational data into the spectral energy distributions of the objects in our final catalogues. The CLFs of the young clusters in both galaxies exhibit approximate power-law behaviour down to the 90 per cent observational completeness limits, thus showing that star cluster formation in the violent environments of starburst rings appears to proceed similarly as that elsewhere in the local Universe. We discuss this result in the context of the density of the interstellar medium in our starburst-ring galaxies.
