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Start Over Subject h alpha photometry Subject open star clusters Subject wide-band photometry Rights public
1. BV(RI)_C_H{alpha} photometry of NGC 663
ID:
ivo://CDS.VizieR/J/A+A/376/144
Title:
BV(RI)_C_H{alpha} photometry of NGC 663
Short Name:
J/A+A/376/144
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present new BV(RI)_C_H{alpha} photometry of the young open cluster NGC 663. The H{alpha} photometry is complete down to magnitude R_C_=15.4, corresponding to spectral type A5 for the cluster members. This allows detection of mild and strong H{alpha} emission in all B-type stars in the cluster. In addition to the 22 Be stars known in the observed field of NGC 663, we discovered four new faint stars of this type. We find that Be stars in NGC 663 cover the whole range of the B spectral type. They are, however, most populous among stars with spectral types falling in the range between B0 and B3, where their fraction amounts to 31+/-8%. Among B-type stars later than B3, Be stars are much less abundant: only 7 out of 101 observed stars, that is, 7+/-3%, were detected. About 70% of the observed Be stars in NGC 663 show detectable variations of light. In the time interval covered by our observations, the ranges of the largest variations reach 0.4mag in the I_C_ band. By means of the isochrone fitting, we derived the cluster distance of 2.1kpc, age of 20-25Myr, and the mean colour excess E(R-I)_C_=0.54mag, with a ~0.1mag scatter due to differential reddening.
2. BV(RI)_C_JHK H{alpha} photometry in IC 5146
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).
3. Catalogue of stellar cluster properties in M83
ID:
ivo://CDS.VizieR/J/MNRAS/417/L6
Title:
Catalogue of stellar cluster properties in M83
Short Name:
J/MNRAS/417/L6
Date:
21 Oct 2021
Publisher:
CDS
Description:
We study the stellar cluster population in two adjacent fields in the nearby, face-on spiral galaxy, M83, using multi-wavelength WFC3/HST imaging. After automatic detection procedures, the clusters are selected through visual inspection to be centrally concentrated, symmetric, and resolved on the images, which allows us to differentiate between clusters and likely unbound associations. We compare our sample with previous studies and show that the differences between the catalogues are largely due to the inclusion of large numbers of diffuse associations within previous catalogues as well as the inclusion of the central starburst region, where the completeness limit is significantly worse than in the surrounding regions. We derive the size distribution of the clusters, which is well described by a log-normal distribution with a peak at ~2.5pc, and find evidence for an expansion in the half-light radius of clusters with age. The luminosity function of the clusters is well approximated by a power-law with index, -2, over most of the observed range, however a steepening is seen at M_V=-9.3 and -8.8 in the inner and outer fields, respectively. Additionally, we show that the cluster population is inconsistent with a pure power-law mass distribution, but instead exhibits a truncation at the high mass end. If described as a Schechter function, the characteristic mass is 1.6 and 0.5x10^5^M_{sun}_, for the inner and outer fields, respectively, in agreement with previous estimates of other cluster populations in spiral galaxies. Comparing the predictions of the mass independent disruption (MID) and mass dependent disruption (MDD) scenarios with the observed distributions, we find that both models can accurately fit the data. However, for the MID case, the fraction of clusters destroyed (or mass lost) per decade in age is dependent on the environment, hence, the age/mass distributions of clusters are not universal. In the MDD case, the disruption timescale scales with galactocentric distance (being longer in the outer regions of the galaxy) in agreement with analytic and numerical predictions. Finally, we discuss the implications of our results on other extragalactic surveys, focussing on the fraction of stars that form in clusters and the need (or lack thereof) for infant mortality.
4. CCD UBVRIHa photometry in NGC 3603
ID:
ivo://CDS.VizieR/J/AJ/127/1014
Title:
CCD UBVRIHa photometry in NGC 3603
Short Name:
J/AJ/127/1014
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present UBVRI and H{alpha} photometry of the extremely compact, starburst cluster NGC 3603. Ground-based images, Hubble Space Telescope (HST) archival data, as well as Chandra X-ray data have been used for this study. We present, for the first time, optical color-magnitude diagrams (CMDs) for the stars in the cluster core down to V=22mag. A well-defined main sequence (MS) as well as low-mass pre-main-sequence (PMS) stars can clearly be seen in the CMDs. This result confirms the finding by Eisenhauer et al. (1998ApJ...498..278E) that low-mass stars are forming in the starburst cluster. We also derive an age (1+/-1Myr) and distance of the cluster (V_0_-M_V_=14.2+/-0.2mag, i.e., d=6.9+/-0.6kpc).
5. h and chi Per UBVI,H{alpha} photometry
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.
6. Lagoon Nebula M8 T tauri accretion rates
ID:
ivo://CDS.VizieR/J/MNRAS/453/1026
Title:
Lagoon Nebula M8 T tauri accretion rates
Short Name:
J/MNRAS/453/1026
Date:
03 Nov 2021
Publisher:
CDS
Description:
We estimate the accretion rates of 235 Classical T Tauri star (CTTS) candidates in the Lagoon Nebula using ugri H{alpha} photometry from the VST Photometric H{alpha} survey+. Our sample consists of stars displaying H{alpha} excess, the intensity of which is used to derive accretion rates. For a subset of 87 stars, the intensity of the u-band excess is also used to estimate accretion rates. We find the mean variation in accretion rates measured using H{alpha} and u-band intensities to be ~0.17dex, agreeing with previous estimates (0.04-0.4dex) but for a much larger sample. The spatial distribution of CTTS align with the location of protostars and molecular gas suggesting that they retain an imprint of the natal gas fragmentation process. Strong accretors are concentrated spatially, while weak accretors are more distributed. Our results do not support the sequential star-forming processes suggested in the literature.
7. Multiwavelength study of NGC 7419
ID:
ivo://CDS.VizieR/J/MNRAS/391/1279
Title:
Multiwavelength study of NGC 7419
Short Name:
J/MNRAS/391/1279
Date:
21 Oct 2021
Publisher:
CDS
Description:
Using new UBVRI H{alpha} CCD photometric observations and the archival infrared and X-ray data, we have carried out a multiwavelength study of a Perseus arm young open star cluster NGC 7419. Using XMM-Newton observations, we found several X-ray sources in the cluster region but none of the Herbig Ae/Be stars is detected in X-rays.
8. NGC 6383 T Tauri accretion rates
ID:
ivo://CDS.VizieR/J/MNRAS/484/5102
Title:
NGC 6383 T Tauri accretion rates
Short Name:
J/MNRAS/484/5102
Date:
03 Nov 2021 13:02:39
Publisher:
CDS
Description:
This paper presents optical (ugriH{alpha})-infrared (JHKs, 3.6-8.0um) photometry and Gaia astrometry of 55 Classical T-Tauri stars (CTTS) in the star-forming region Sh 2-012 and its central cluster NGC 6383. The sample was identified based on photometric H{alpha} emission linewidths, and has a median age of 2.8+/-1.6Myr, with a mass range between 0.3 and 1M_{sun}_. 94 per cent of CTTS with near-infrared cross-matches fall on the near-infrared T-Tauri locus, with all stars having mid-infrared photometry exhibiting evidence for accreting circumstellar discs. CTTS are found concentrated around the central cluster NGC 6383, and towards the bright rims located at the edges of Sh 2-012. Stars across the region have similar ages, suggestive of a single burst of star formation. Mass accretion rates dMacc/dt) estimated via H{alpha} and u-band line intensities show a scatter (0.3dex) similar to spectroscopic studies, indicating the suitability of H{alpha} photometry to estimate dMacc/dt. Examining the variation of dMacc/dt with stellar mass (M*), we find a smaller intercept in the (dMacc/dt)-M* relation than oft-quoted in the literature, providing evidence to discriminate between competing theories of protoplanetary disc evolution.
9. NGC 6231 UBVRI and H{alpha} photometry
ID:
ivo://CDS.VizieR/J/AJ/115/734
Title:
NGC 6231 UBVRI and H{alpha} photometry
Short Name:
J/AJ/115/734
Date:
21 Oct 2021
Publisher:
CDS
Description:
UBVRI and H{alpha} CCD photometry has been obtained for the young open cluster NGC 6231. From the R-H{alpha} color, a measure of the H{alpha} emission, we find 12 pre-main-sequence (PMS) members and seven possible PMS members in the cluster. Applying recent stellar evolutionary tracks and PMS evolutionary tracks, we derive the age, age spread, and initial mass function of the cluster. The initial mass function of NGC 6231 is a Gaussian with a turnover at logm~0.4 (m~2.5M_{Sun}_) and shows an abrupt decrease in the number of low-mass stars. Possible reasons for the suppression of low-mass star formation and star formation processes are discussed.
10. Optical & Spitzer photometry in IC 1805
ID:
ivo://CDS.VizieR/J/ApJS/230/3
Title:
Optical & Spitzer photometry in IC 1805
Short Name:
J/ApJS/230/3
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present deep wide-field optical CCD photometry and mid-infrared Spitzer/IRAC and MIPS 24{mu}m data for about 100000 stars in the young open cluster IC 1805. The members of IC 1805 were selected from their location in the various color-color and color-magnitude diagrams, and the presence of H{alpha} emission, mid-infrared excess emission, and X-ray emission. The reddening law toward IC 1805 is nearly normal (R_V_=3.05+/-0.06). However, the distance modulus of the cluster is estimated to be 11.9+/-0.2mag (d=2.4+/-0.2kpc) from the reddening-free color-magnitude diagrams, which is larger than the distance to the nearby massive star-forming region W3(OH) measured from the radio VLBA astrometry. We also determined the age of IC 1805 ({tau}_MSTO_=3.5Myr). In addition, we critically compared the age and mass scale from two pre-main-sequence evolution models. The initial mass function with a Salpeter-type slope of {Gamma}=-1.3+/-0.2 was obtained and the total mass of IC 1805 was estimated to be about 2700+/-200M_{sun}_. Finally, we found our distance determination to be statistically consistent with the Tycho-Gaia Astrometric Solution Data Release 1, within the errors. The proper motion of the B-type stars shows an elongated distribution along the Galactic plane, which could be explained by some of the B-type stars being formed in small clouds dispersed by previous episodes of star formation or supernova explosions.

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