- ID:
- ivo://CDS.VizieR/J/A+AS/139/393
- Title:
- Young Massive Star Clusters. II.
- Short Name:
- J/A+AS/139/393
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Table 4 lists photometric data for Young Massive Star Clusters identified in a sample of 21 nearby galaxies. The photometric data have been corrected for Galactic foreground extinction. Each cluster is identified by the abbreviated NGC number of its host galaxy and an object number: nxxx-yyy is object number yyy in the galaxy NGC xxx. Effective cluster radii have been obtained by modeling the cluster images as MOFFAT15 functions convolved with the point-spread function measured on the CCD images.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/695/511
- Title:
- Young massive stars in LHA 120-N 44
- Short Name:
- J/ApJ/695/511
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The HII complex N44 in the Large Magellanic Cloud (LMC) provides an excellent site to perform a detailed study of star formation in a mild starburst, as it hosts three regions of star formation at different evolutionary stages, and it is not as complicated and confusing as the 30 Doradus giant HII region. We have obtained Spitzer Space Telescope observations and complementary ground-based 4m uBVIJK observations of N44 to identify candidate massive young stellar objects (YSOs). We further classify the YSOs into Types I, II, and III, according to their spectral energy distributions (SEDs). In our sample of 60 YSO candidates, ~65% of them are resolved into multiple components or extended sources in high-resolution ground-based images.
- ID:
- ivo://CDS.VizieR/J/MNRAS/454/593
- Title:
- Young moving groups in solar neighbourhood
- Short Name:
- J/MNRAS/454/593
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a self-consistent, absolute isochronal age scale for young (<~200Myr), nearby (<~100pc) moving groups in the solar neighbourhood based on homogeneous fitting of semi-empirical pre-main-sequence model isochrones using the {tau}^2^ maximum-likelihood fitting statistic of Naylor & Jeffries (2006MNRAS.373.1251N) in the M_V_, V-J colour-magnitude diagram. The final adopted ages for the groups are as follows: 149^+51^_-19_Myr for the AB Dor moving group, 24+/-3Myr for the {beta} Pic moving group (BPMG), 45^+11^_-7_Myr for the Carina association, 42^+6^_-4_Myr for the Columba association, 11+/-3Myr for the {eta} Cha cluster, 45+/-4Myr for the Tucana-Horologium moving group (Tuc-Hor), 10+/-3Myr for the TW Hya association and 22^+4^_-3_Myr for the 32 Ori group. At this stage we are uncomfortable assigning a final, unambiguous age to the Argus association as our membership list for the association appears to suffer from a high level of contamination, and therefore it remains unclear whether these stars represent a single population of coeval stars. Our isochronal ages for both the BPMG and Tuc-Hor are consistent with recent lithium depletion boundary (LDB) ages, which unlike isochronal ages, are relatively insensitive to the choice of low-mass evolutionary models. This consistency between the isochronal and LDB ages instils confidence that our self-consistent, absolute age scale for young, nearby moving groups is robust, and hence we suggest that these ages be adopted for future studies of these groups. Software implementing the methods described in this study is available from http://www.astro.ex.ac.uk/people/timn/tau-squared/.
- ID:
- ivo://CDS.VizieR/J/A+A/507/1485
- Title:
- Young (proto)stellar population in L1630
- Short Name:
- J/A+A/507/1485
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the young (proto)stellar population in NGC 2023 and the L 1630 molecular cloud bordering the H II region IC 434, using Spitzer IRAC and MIPS archive data, JCMT SCUBA imaging and spectroscopy as well as targeted BIMA observations of one of the Class 0 protostars, NGC 2023 MM 1. We study the distribution of gas, dust and young stars in this region to see where stars are forming, whether the expansion of the H II region has triggered star formation, and whether dense cold cores have already formed stars. We have performed photometry of all IRAC and MIPS images, and used color-color diagrams to identify and classify all young stars seen within a 22'x26' field along the boundary between IC 434 and L 1630.
- ID:
- ivo://CDS.VizieR/J/AJ/109/960
- Title:
- Young star clusters in The Antennae
- Short Name:
- J/AJ/109/960
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- New high-resolution images of the disks of NGC 4038/4039 obtained with the Wide Field Camera of the Hubble Space Telescope (HST) are presented. NGC 4038/4039, nicknamed "The Antennae," is a prototypical example of a pair of colliding galaxies believed to be at an early stage of a merger. Down to the limiting magnitude of V~23mag, the HST images reveal a population of over 700 blue pointlike objects within the disks. The mean absolute magnitude of these objects is M_V_=-11mag, with the brightest objects reaching M_V_~-15. Their mean apparent color indices are U-V=-0.7mag and V-I=0.8mag on the Johnson UVI passband system, while their mean indices corrected for internal reddening are (U-V)_0_=-1.0mag and (V-I)_0_=0.5. Their mean effective radius, determined from slightly resolved images, is 18pc (for H0=50km/s/Mpc). Based on their luminosities and resolution, most of these objects cannot be individual stars, but are likely young compact star clusters. The brighter ones are similar to the objects found in NGC 1275 and NGC 7252, which appear to be young globular clusters formed during recent galaxy mergers. Based on their U-V and V-I colors, the brightest, bluest clusters of NGC 4038/4039 appear to be less than 10Myr old. Most of these bright clusters are relatively tightly clustered themselves, with typically a dozen individual clusters belonging to a complex identified as a giant H II region from ground-based observations. The cluster luminosity function (LF) is approximately a power law, {Phi}(L)dL is proportional to L^(-1.78+/-0.05)^dL, with no hint of a turnover at fainter magnitudes. This power-law shape agrees with the LF of Magellanic Cloud clusters and Galactic open clusters, but differs from the LF of old globular cluster systems that is typically Gaussian with a FWHM of ~3mag. Possible explanations for this apparent difference include: (1) We have not observed faint enough to see the turnover, (2) the initial LF of star clusters is a power law but the fainter objects dissolve with time, (3) conditions at the present epoch favor the formation of a wide range of cluster masses while conditions at earlier epochs favored the formation of massive clusters, and (4) the NGC 4038/4039 clusters may not evolve into normal globular clusters. Besides the blue clusters, we also find about a dozen extremely red objects with V-I>3.0. The highest number density of these red objects is found in the SE quadrant, where star formation appears to be most recent. We propose that these objects may be very young star clusters still embedded in their placental dust cocoons.
- ID:
- ivo://CDS.VizieR/J/ApJ/794/124
- Title:
- Young star forming region NGC 2264 Spitzer sources
- Short Name:
- J/ApJ/794/124
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Spitzer 3.6, 4.5, 5.8, 8.0, and 24 {mu}m images of the Mon OB1 East giant molecular cloud, which contains the young star forming region NGC 2264, as well as more extended star formation. With Spitzer data and Two Micron All Sky Survey photometry, we identify and classify young stellar objects (YSOs) with dusty circumstellar disks and/or envelopes in Mon OB1 East by their infrared-excess emission and study their distribution with respect to cloud material. We find a correlation between the local surface density of YSOs and column density of molecular gas as traced by dust extinction that is roughly described as a power law in these quantities. NGC 2264 follows a power-law index of ~2.7, exhibiting a large YSO surface density for a given gas column density. Outside of NGC 2264 where the surface density of YSOs is lower, the power law is shallower and the region exhibits a larger gas column density for a YSO surface density, suggesting the star formation is more recent. In order to measure the fraction of cloud members with circumstellar disks/envelopes, we estimate the number of diskless pre-main-sequence stars by statistical removal of background star detections. We find that the disk fraction of the NGC 2264 region is 45%, while the surrounding, more distributed regions show a disk fraction of 19%. This may be explained by the presence of an older, more dispersed population of stars. In total, the Spitzer observations provide evidence for heterogenous, non-coeval star formation throughout the Mon OB1 cloud.
- ID:
- ivo://CDS.VizieR/J/A+A/485/931
- Title:
- Young stars and brown dwarfs in Ori OB1b
- Short Name:
- J/A+A/485/931
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present here exhaustive lists of known young stars and new candidate members around Alnilam and Mintaka in the Ori OB1b association as well as of fore- and background sources. A total of 133 stars display features of extreme youth, including early spectral types, lithium in absorption, or mid-infrared flux excess. Other two young brown dwarf and 289 star candidates have been identified from an optical/near-infrared colour-magnitude diagram. We list additional 74 known objects that might belong to the association. This compilation of tables can serve as an input for characterisation of the stellar and high-mass substellar populations in the Orion Belt.
- ID:
- ivo://CDS.VizieR/J/MNRAS/403/545
- Title:
- Young stars in Cepheus OB3b
- Short Name:
- J/MNRAS/403/545
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a photometric study of I-band variability in the young association Cepheus OB3b. The study is sensitive to periodic variability on time-scales of less than a day, to more than 20d. After rejection of contaminating objects using V, I, R and narrow-band H{alpha} photometry, we find 475 objects with measured rotation periods, which are very likely pre-main-sequence members of the Cep OB3b star-forming region.
- ID:
- ivo://CDS.VizieR/J/AJ/130/188
- Title:
- Young stars in Trumpler 37 and NGC 7160
- Short Name:
- J/AJ/130/188
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of MMT observations of young stars for our study of protoplanetary disks at ages 1-10Myr in two young clusters located in the Cepheus OB2 region: Trumpler 37 (embedded in the HII region IC 1396) and NGC 7160. Using low-resolution optical spectra from the Hectospec multifiber spectrograph, we have tripled the number of known low-mass cluster members, identifying 130 new members in Tr 37 and 30 in NGC 7160. We use indicators of youth (Li absorption at 6707{AA}) and accretion/chromospheric activity (H{alpha} emission) to identify and classify the low-mass cluster members. We derive spectral types for all the low-mass candidates and calculate the individual extinctions and the average over the clusters.
- ID:
- ivo://CDS.VizieR/J/A+A/557/A29
- Title:
- Young stellar clusters in the Rosette
- Short Name:
- J/A+A/557/A29
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Rosette complex is a well studied region of the galactic plane which presents the apparent characteristics of a triggered star forming region. This is however still debated as no strong evidence corroborates this statement. We focused on characterizing the young stellar population in the Rosette to improve our understanding of the processes that regulate the star formation in this region. We propose an original method relying on the joint analysis of the star color and density in the near-infrared. It yielded the identification of 13 clusters, 2 of them being new discoveries. Based on their spectral index from UKIDSS K-band to WISE W3-band, we identified 535 YSO candidates within these cluster boundaries.
