- ID:
- ivo://CDS.VizieR/J/ApJ/675/1233
- Title:
- gri photometry in M37 (NGC 2099)
- Short Name:
- J/ApJ/675/1233
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have conducted a deep (15~<r~<23 ), 20 night survey for transiting planets in the intermediate-age open cluster M37 (NGC 2099) using the Megacam wide-field mosaic CCD camera on the 6.5m MMT. In this paper we describe the observations and data reduction procedures for the survey and analyze the stellar content and dynamical state of the cluster. By combining high-resolution spectroscopy with existing BVI_C_K_s and new gri color-magnitude diagrams, we determine the fundamental cluster parameters: t=485+/-28Myr, without overshooting (t=550+/-30Myr, with overshooting), E(B-V)=0.227+/-0.038, (m-M)_V_=11.57+/-0.13, and [M/H]=+0.045+/-0.044, which are in good agreement with, although more precise than, previous measurements. We determine the mass function down to 0.3M_{sun}_ and use this to estimate the total cluster mass of 3640+/-170M_{sun}_.
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- ID:
- ivo://CDS.VizieR/J/ApJ/857/132
- Title:
- gri photometry of NGC 796 cluster
- Short Name:
- J/ApJ/857/132
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- NGC 796 is a massive young cluster located 59kpc from us in the diffuse intergalactic medium of the 1/5-1/10Z_{sun}_ Magellanic Bridge, allowing us to probe variations in star formation and stellar evolution processes as a function of metallicity in a resolved fashion, and providing a link between resolved studies of nearby solar-metallicity and unresolved distant metal-poor clusters located in high-redshift galaxies. In this paper, we present adaptive optics griH{alpha} imaging of NGC 796 (at 0.5", which is ~0.14pc at the cluster distance) along with optical spectroscopy of two bright members to quantify the cluster properties. Our aim is to explore whether star formation and stellar evolution vary as a function of metallicity by comparing the properties of NGC 796 to higher-metallicity clusters. We find an age of 20_-5_^+12^Myr from isochronal fitting of the cluster main sequence in the color-magnitude diagram. Based on the cluster luminosity function, we derive a top-heavy stellar initial mass function (IMF) with a slope {alpha}=1.99+/-0.2, hinting at a metallicity and/or environmental dependence of the IMF, which may lead to a top-heavy IMF in the early universe. Study of the H{alpha} emission-line stars reveals that classical Be stars constitute a higher fraction of the total B-type stars when compared with similar clusters at greater metallicity, providing some support to the chemically homogeneous theory of stellar evolution. Overall, NGC 796 has a total estimated mass of 990+/-200M_{sun}_, and a core radius of 1.4+/-0.3pc, which classifies it as a massive young open cluster, unique in the diffuse interstellar medium of the Magellanic Bridge.
- ID:
- ivo://CDS.VizieR/J/MNRAS/465/2748
- Title:
- Haffner 9 CT1 photometry
- Short Name:
- J/MNRAS/465/2748
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We turn our attention to Haffner 9, a Milky Way open cluster whose previous fundamental parameter estimates are far from being in agreement. In order to provide with accurate estimates, we present high-quality Washington CT_1_ and Johnson BVI photometry of the cluster field. We put particular care in statistically cleaning the colour-magnitude diagrams (CMDs) from field star contamination, which was found a common source in previous works for the discordant fundamental parameter estimates. The resulting cluster CMD fiducial features were confirmed from a proper motion membership analysis. Haffner 9 is a moderately young object (age~350Myr), placed in the Perseus arm - at a heliocentric distance of ~3.2kpc - , with a lower limit for its present mass of ~160M_{sun}_ and of nearly metal solar content. The combination of the cluster structural and fundamental parameters suggest that it is in an advanced stage of internal dynamical evolution, possibly in the phase typical of those with mass segregation in their core regions. However, the cluster still keeps its mass function close to that of the Salpeter's law.
- ID:
- ivo://CDS.VizieR/J/other/RMxAA/38.141
- Title:
- Haffner 19 UBV(RI)_c_ photometry
- Short Name:
- J/other/RMxAA/38
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present broad-band UBV(RI)_c_ CCD imagery of 334 stars in the direction of the Galactic cluster Haffner 19. The sample is complete to m{lambda}=19 ({lambda} = U, B, V, R, I). We reliably establish the cluster membership for 102 stars based upon their locations in the (V, B-V), (V, V-I), (I, R-I), (U-B, B-V), and (V-R, V-I) diagrams, thus increasing three-fold the number of known cluster members. With the Q-method we determine the MK spectral types of the 33 brightest stars, confirming that 29 belong to the cluster's young population (15 B0-B1 and 14 B2- B9 main sequence stars). Complementary uvby{beta} photoelectric photometry of 6 bright stars independently confirms the distance and reddening to the cluster.
- ID:
- ivo://CDS.VizieR/J/AJ/122/248
- Title:
- h and chi Per UBVI,H{alpha} photometry
- Short Name:
- J/AJ/122/248
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- UBVI and H{alpha} photometry is presented for 17319 stars in vicinity of the young double cluster h and {chi} Persei. Our photometry extends over a 37'x1{deg} field centered on the association. We construct reddening contours within the imaged field. We find that the two clusters share a common distance modulus of 11.75+/-0.05 and ages of log[age(yr)]=7.1+/-0.1. From the V-H{alpha} color, a measure of the H{alpha} emission strength, we conduct a survey for emission line objects within the association. We detect a sample of 33 Be stars, eight of which are new detections. We present a scenario of evolutionary enhancement of the Be phenomenon to account for the peak in Be fraction toward the top of the main sequence in the population of h and {chi} Persei and similar young clusters. UBVI and H{alpha} photometry was performed on five nights between 1999 August 17 and 25 at the San Diego State University Mount Laguna Observatory with the 1m telescope and a Loral 2048x2048 CCD.
- ID:
- ivo://CDS.VizieR/J/MNRAS/408/475
- Title:
- HATNet Pleiades Rotation Period Catalogue
- Short Name:
- J/MNRAS/408/475
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using data from the Hungarian-made Automated Telescope Network (HATNet) survey for transiting exoplanets, we measure photometric rotation periods for 368 Pleiades stars with 0.4~<M~<1.3M_{sun}_. We detect periodic variability for 74 per cent of the cluster members in this mass range that are within our field-of-view, and 93 per cent of the members with 0.7~<M~<1.0M_{sun}_. This increases, by a factor of 5, the number of Pleiades members with measured periods. We compare these data to the rich sample of spectroscopically determined projected equatorial rotation velocities (vsini) available in the literature for this cluster. Included in our sample are 14 newly identified probable cluster members which have proper motions, photometry and rotation periods consistent with membership.
- ID:
- ivo://CDS.VizieR/J/A+A/371/908
- Title:
- Havlen-Moffat No. 1 UBVRI photometry
- Short Name:
- J/A+A/371/908
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A deep CCD UBVRI photometric survey combined with UBVRI polarimetric observations of 21 bright stars was carried out in the region of the open cluster Havlen-Moffat No. 1. Our data reveal that the extinction law in this cluster es variable and that six cluster stars show very high polarisation values (>4%), probably because of the presence of a nearby small dust cloud. The cluster is at a distance of d=3300pc, it is 2-4Myr old and the initial mass function of its most massive stars (M>3M_{sun}_) has a flat slope of x about of 0.7. As an additional result, it was possible to reconcile the absolute magnitudes of the two WN7-type members using the R-values valid in the regions where they are located.
- ID:
- ivo://CDS.VizieR/J/MNRAS/472/1760
- Title:
- Hierarchical formation of Westerlund 1
- Short Name:
- J/MNRAS/472/1760
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We examine the level of substructure and mass segregation in the massive, young cluster Westerlund 1. We find that it is relatively smooth, with little or no mass segregation, but with the massive stars in regions of significantly higher than average surface density. While an expanding or bouncing-back scenario for the evolution of Westerlund 1 cannot be ruled out, we argue that the most natural model to explain these observations is one in which Westerlund 1 formed with no primordial mass segregation and at a similar or larger size than we now observe.
99. IC 4665
- ID:
- ivo://CDS.VizieR/J/AJ/105/1441
- Title:
- IC 4665
- Short Name:
- J/AJ/105/1441
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The results of a combined astrometric, photometric, and spectroscopic program to identify members of the open cluster IC 4665 are presented. Numerous new proper motion/photometric candidate members and at least 23 M dwarfs with H-alpha emission have been identified. A reanalysis of IC 4665's age using different methods yields conflicting results ranging from approx. 3x10^7^ yr to the age of the Pleiades. This study provides a list of candidate cluster members in the intermediate and low-mass regime of this cluster. Future spectroscopic observations of these candidates should eventually identify true cluster members. The results of new echelle observations of some candidates and the photometric monitoring of one apparent cluster member are given in an appendix.
- ID:
- ivo://CDS.VizieR/J/AJ/116/1801
- Title:
- IC 4996 CCD photometry
- Short Name:
- J/AJ/116/1801
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The results of a UBV CCD photometric study of the cluster IC 4996 are presented. We obtain new values for the cluster parameters: E(B-V)=0.71+/-0.08, V_0_-M_V_=11.9+/-0.1, and age=(7.5+/-3)x10^6^yr. The combined evidence from the photometric diagrams suggests the presence of a number of premain-sequence (PMS) cluster members with spectral types ~A0 to F5. The interpretation of these objects as PMS candidates is further supported by independent results from CCD uvbyH{beta} observations. If confirmed, these stars would bridge the existing gap in the sample of PMS stars, between the coolest Herbig AeBe stars (HAeBe), and the hottest T Tauri stars. These PMS candidates are located some 0.5 and 1 mag above the main sequence in the V-(B-V) diagram, around the location of spectral types AF. This feature, together with their locations in the (U-B)-(B-V) diagram and the interpretation that they are PMS members, suggest an additional reddening law with a slope {alpha}=E(U-B)/E(B-V)~0.55, probably caused by circumstellar material.