- ID:
- ivo://CDS.VizieR/J/MNRAS/415/1202
- Title:
- BVI photometry in W5E HII region
- Short Name:
- J/MNRAS/415/1202
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The aim of this paper is to present the results of photometric investigations of the central cluster of the W5 E HII region as well as a follow-up study of the triggered star formation in and around bright-rimmed clouds (BRCs). We have carried out wide-field UBVIc and deep VIc photometry of the W5 E HII region. A distance of ~2.1kpc and a mean age of ~1.3Myr have been obtained for the central cluster. The young stellar objects (YSOs) associated with the region are identified on the basis of near-infrared and mid-infrared observations.
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- ID:
- ivo://CDS.VizieR/J/MNRAS/375/1220
- Title:
- BVI photometry of young stars in 10 clusters
- Short Name:
- J/MNRAS/375/1220
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have selected pre-main-sequence (PMS) stars in 12 groups of notional ages ranging from 1 to 35Myr, using heterogeneous membership criteria. Using these members we have constructed empirical isochrones in V, V-I colour-magnitude diagrams. This allows us to identify clearly the gap between the radiative main sequence and the convective PMS (the RC gap). We follow the evolution of this gap with age and show that it can be a useful age indicator for groups less than =15 Myr old. We also observe a reduction in absolute spreads about the sequences with age. Finally, the empirical isochrones allow us to place the groups in order of age, independently of theory. The youngest groups can be collated into three sets of similar ages. The youngest set is the ONC, NGC 6530 and IC 5146 (nominally 1Myr); next Cep OB3b, NGC 2362, Ori and NGC 2264 (nominally 3Myr); and finally Ori and IC 348 (nominally 45Myr). This suggests Cep OB3b is younger than previously thought, and IC 348 older. For IC 348 the stellar rotation rate distribution and fraction of stars with discs imply a younger age than we derive. We suggest this is because of the absence of O-stars in this cluster, whose winds and/or ionizing radiation may be an important factor in the removal of discs in other clusters.
- ID:
- ivo://CDS.VizieR/J/ApJ/549/578
- Title:
- BV photometry of Trumpler 14 and 16
- Short Name:
- J/ApJ/549/578
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- H-R diagrams are presented for the very young galactic clusters Trumpler 14 and Trumpler 16, which are the two most populous clusters in the region of vigorous star formation surrounding {eta} Carinae. Point spread function photometry of UBV CCD images is presented down to V~19 for over 560 stars in Tr 16 and 290 stars in Tr 14. We have also obtained similar data for a local background field. After determining cluster membership through proper motions from a previous work, we find that the reddening of cluster members is significantly lower than that of the local background stars. Thus, we are able to use individual reddenings to identify likely members at far deeper levels than possible with proper motions. This work has revealed a significant population of pre-main-sequence (PMS) stars in both clusters. The location of the PMS stars in the H-R diagram indicates that the theoretical "stellar birthline" of Palla & Stahler (1990ApJ...360L..47P, follows the locus of stars far better than that of Beech & Mitalas (1994ApJS...95..517B). Comparison with both pre- and post-main-sequence isochrones also reveals that although intermediate-mass stars have been forming continuously over the last 10Myr, the high-mass stars formed within the last 3Myr. There is no evidence that the formation of the intermediate-mass stars was truncated by the formation of the high-mass stars.
- ID:
- ivo://CDS.VizieR/J/AJ/123/304
- Title:
- BV(RI)_C_JHK H{alpha} photometry in IC 5146
- Short Name:
- J/AJ/123/304
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The B0V star BD+46 3474 lies near the front surface of a dense molecular cloud and illuminates the emission/reflection nebula IC 5146. The HAeBe variable BD +46 3471 is embedded in the same cloud, about 10' (3.5pc) away. CCD photometry in BV(RI)_C_ (to V=22) and in JHK (to about K=16.5) has been obtained for the young clusters surrounding each of these two bright stars. Some 100 emission-H{alpha} stars brighter than R=20.5 have been found in the area, most of them in IC 5146. (Among these are two that have spectra resembling a high-excitation Herbig-Haro [HH] object plus a stellar continuum).
- ID:
- ivo://CDS.VizieR/J/AJ/128/2316
- Title:
- BVRIJHKs photometry in sigma Ori cluster
- Short Name:
- J/AJ/128/2316
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report an optical photometric survey of 0.89deg^2^ of the Orion OB1b association centered on sigma Ori. This region includes most of the sigma Ori cluster, the highest-density region within Orion OB1b. We have developed a statistical procedure to identify the young, low-mass, pre-main-sequence population of the association. We estimate that the cluster has 160 members in the mass range (0.2M_{sun}_<=M<=1.0M_{sun}_). The cluster has a radius of 35pc and an estimated age of 2.5+/-0.3Myr. We estimate that the total mass of the cluster is 225+/-30M_{sun}_. This mass is similar to the estimated mass of the ~5x10^5^yr old cluster NGC 2024. NGC 2024 and sigma Ori appear to be a well-matched pair of clusters, except for the ~2Myr difference in their ages.
- ID:
- ivo://CDS.VizieR/J/A+A/556/A60
- Title:
- BVRI observations of the FUor star V582 Aur
- Short Name:
- J/A+A/556/A60
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from optical photometric and spectroscopic observations of the eruptive pre-main sequence star V582 Aur. Variability of the star was reported a few years ago when it was suspected as a possible FU Orionis object. Due to the small number of currently known FUors, a new object of this type is ideal target for follow-up photometric and spectroscopic observations. We carried out BVRI CCD photometric observations in the field of V582 Aur from 2009 August to 2013 April. We acquired high-, medium-, and low-resolution spectroscopy of V582 Aur during this period. To study the pre-outburst variability of the target and construct its historical light curve, we searched for archival observations in photographic plate collections. The pre-outburst photographic observations of V582 Aur show low-amplitude light variations typical of T Tauri stars. Archival photographic observations indicate that the increase in brightness began in late 1984 or early 1985 and the star reached the maximum level of brightness at 1986 January. Our BVRI photometric observations show large amplitude variations ({Delta}V~2.8mag.) during the 3.5 year period of observations. Most of the time, however, the star remains in a state close to the maximum brightness. The deepest drop in brightness was observed in the spring of 2012, when the brightness of the star fell to a level close to the pre-outburst. The multicolor photometric data show a color reversal during the minimum in brightness, which is typical of UX Ori variables.
- ID:
- ivo://CDS.VizieR/J/A+A/345/521
- Title:
- BVRI photometry of NGC 2264
- Short Name:
- J/A+A/345/521
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The pre-main-sequence (PMS) population in the mass range between =~0.2 and =~3M_{sun}_ in southern part of the star-forming region NGC 2264 has been studied, determining both the Initial Mass Function in the region as well as the star-formation rates for different mass ranges. The sample is a composite one, derived through the union of samples obtained through different techniques and each suffering from different biases: previously known PMS stars in the region from the literature, photometrically-selected T Tauri candidates (from our own photometric data, discussed in detail in the present paper) and X-ray selected PMS candidates (discussed in detail in a companion paper) have been joined to form a sample which we show to be statistically complete (i.e. free from the biases which affect each of the parent samples) down to =~0.6M_{sun}_ (while being incomplete at lower masses). Individual masses and ages have been derived by placing the individual stars on evolutionary tracks, allowing us to derive both the IMF and the star formation rate. The Initial Mass Function thus derived for NGC 2264 shows evidence for a bimodal distribution of masses, with a break in the IMF at around 1M_{sun}_.
- ID:
- ivo://CDS.VizieR/J/other/BAJ/24.62
- Title:
- BVRI Photometry of 14 PMS stars
- Short Name:
- J/other/BAJ/24.6
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- New photometric data from CCD multicolour BVRI observations of 14 pre-main sequence stars during the period from 2013 April to 2015 September are presented. The studied objects are located in the field of 'Gulf of Mexico' in the NGC 7000/IC 5070 star-forming complex. The stars from our study exhibit different types of photometric variability in all optical passbands. Using our long-term observations and data published by other authors, we tried to define the reasons for the observed brightness variations. On the basis of our new data previously unknown periodicity in the light curve of the star LkHa 189 (2.45-days) was registered.
- ID:
- ivo://CDS.VizieR/J/other/BAJ/22.3
- Title:
- BVRI photometry of 5 PMS stars
- Short Name:
- J/other/BAJ/22.3
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new data from BVRI photometric observations of five PMS stars during the period from April 2013 to July 2014. The stars are located in the field of NGC 7000/IC 5070 ("Gulf of Mexico") - a region with active star formation. The presented paper is a continuation of our long-term photometric investigations of the young stellar objects in this region. The long-term multicolor photometric observations of PMS stars are very important for their exact classification. Our results show that the studied stars exhibit different types of photometric variability in all bands. We tried to classify them using our data from the long-term photometry and data published by other authors.
- ID:
- ivo://CDS.VizieR/J/AJ/131/2959
- Title:
- Candidate low-mass PMS in 25 Orionis group
- Short Name:
- J/AJ/131/2959
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The stellar group surrounding the Be (B1Vpe) star 25 Ori was discovered to be a pre-main-sequence (PMS) population by the CIDA Variability Survey of Orion (Cat. J/AJ/129/907) and subsequent spectroscopy. We analyze Sloan Digital Sky Survey multiepoch photometry to map the southern extent of the 25 Ori group and characterize its PMS population. We compare this group to the neighboring Orion OB1a and OB1b subassociations and to active star formation sites (NGC 2068/NGC 2071) within the LDN 1630 dark cloud. We find that the 25 Ori group has a radius of 1.4{deg}, corresponding to 8-11pc at the distances of Orion OB1a and OB1b.