- ID:
- ivo://CDS.VizieR/J/AJ/154/163
- Title:
- WISE-selected candidate SFRs beyond the Outer Arm
- Short Name:
- J/AJ/154/163
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The outer Galaxy beyond the Outer Arm provides a good opportunity to study star formation in an environment significantly different from that in the solar neighborhood. However, star-forming regions in the outer Galaxy have never been comprehensively studied or cataloged because of the difficulties in detecting them at such large distances. We studied 33 known young star-forming regions associated with 13 molecular clouds at R_G_>=13.5 kpc in the outer Galaxy with data from the Wide-field Infrared Survey Explorer (WISE) mid-infrared all-sky survey (Wright et al. 2010AJ....140.1868W; Jarrett et al. 2011ApJ...735..112J). From their color distribution, we developed a simple identification criterion of star-forming regions in the outer Galaxy with the WISE color. We applied the criterion to all the WISE sources in the molecular clouds in the outer Galaxy at R_G_>=13.5 kpc detected with the Five College Radio Astronomy Observatory (FCRAO) ^12^CO survey of the outer Galaxy (Heyer et al. 1998ApJS..115..241H), of which the survey region is 102.49{deg}=<l=<141.54{deg}, -3.03{deg}=<b=<5.41{deg}, and successfully identified 711 new candidate star-forming regions in 240 molecular clouds. The large number of samples enables us to perform the statistical study of star formation properties in the outer Galaxy for the first time. This study is crucial to investigate the fundamental star formation properties, including star formation rate, star formation efficiency, and initial mass function, in a primordial environment such as the early phase of the Galaxy formation.
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/453/133
- Title:
- WISE view of RV Tauri stars
- Short Name:
- J/MNRAS/453/133
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a detailed study based on infrared (IR) photometry of all Galactic RV Tauri stars from the General Catalogue of Variable Stars (GCVS). RV Tauri stars are the brightest among the Population II Cepheids. They are thought to evolve away from the asymptotic giant branch (AGB) towards the white dwarf domain. IRAS detected several RV Tauri stars because of their large IR excesses and it was found that they occupy a specific region in the [12]-[25], [25]-[60] IRAS two-colour diagram. We used the all sky survey of Wide-field Infrared Survey Explorer to extend these studies and compare the IR properties of all RV Tauri stars in the GCVS with a selected sample of post-AGB objects with the goal to place the RV Tauri pulsators in the context of post-AGB evolution. Moreover, we correlated the IR properties of both the RV Tauri stars and the comparison sample with other observables like binarity and the presence of a photospheric chemical anomaly called depletion. We find that Galactic RV Tauri stars display a range of IR properties and we differentiate between disc sources, objects with no IR excess and objects for which the spectral energy distribution (SED) is uncertain. We obtain a clear correlation between disc sources and binarity. RV Tauri stars with a variable mean magnitude are exclusively found among the disc sources. We also find evidence for disc evolution among the binaries. Furthermore our studies show that the presence of a disc seems to be a necessary but not sufficient condition for the depletion process to become efficient.
- ID:
- ivo://CDS.VizieR/J/AJ/150/100
- Title:
- WISE YSO candidates near {sigma} and {lambda} Ori
- Short Name:
- J/AJ/150/100
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have conducted a sensitive search down to the hydrogen burning limit for unextincted stars over ~200 square degrees around Lambda Orionis and 20 square degrees around Sigma Orionis using the methodology of Koenig & Leisawitz (2014ApJ...791..131K; K14). From WISE and 2MASS data we identify 544 and 418 candidate young stellar objects (YSOs) in the vicinity of {lambda} and {sigma} respectively. Based on our followup spectroscopy for some candidates and the existing literature for others, we found that ~80% of the K14-selected candidates are probable or likely members of the Orion star-forming region. The yield from the photometric selection criteria shows that WISE sources with K_S_-w3>1.5mag and K_S_ between 10 and 12mag are most likely to show spectroscopic signs of youth, while WISE sources with K_S_-w3>4mag and K_s_>12 were often active galactic nuclei when followed up spectroscopically. The population of candidate YSOs traces known areas of active star formation, with a few new "hot spots" of activity near Lynds 1588 and 1589 and a more dispersed population of YSOs in the northern half of the HII region bubble around {sigma} and {epsilon} Ori. A minimal spanning tree analysis of the two regions to identify stellar groupings finds that roughly two-thirds of the YSO candidates in each region belong to groups of 5 or more members. The population of stars selected by WISE outside the MST groupings also contains spectroscopically verified YSOs, with a local stellar density as low as 0.5 stars per square degree.
- ID:
- ivo://CDS.VizieR/J/AJ/148/85
- Title:
- WIYN open cluster study. LXII. Photometry of M35
- Short Name:
- J/AJ/148/85
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The current generation of stellar isochrone models exhibits non-negligible discrepancies due to variations in the input physics. The success of each model is determined by how well it fits the observations, and this paper aims to disentangle contributions from the various physical inputs. New deep, wide-field optical and near-infrared photometry (UBVRIJHK_S_) of the cluster M35 is presented, against which several isochrone systems are compared: Padova, PARSEC, Dartmouth, and Y^2^. Two different atmosphere models are applied to each isochrone: ATLAS9 and BT-Settl. For any isochrone set and atmosphere model, observed data are accurately reproduced for all stars more massive than 0.7M_{sun}_. For stars less massive than 0.7M_{sun}_, Padova and PARSEC isochrones consistently produce higher temperatures than observed. Dartmouth and Y^2^ isochrones with BT-Settl atmospheres reproduce optical data accurately; however, they appear too blue in IR colors. It is speculated that molecular contributions to stellar spectra in the near-infrared may not be fully explored, and that future study may reconcile these differences.
- ID:
- ivo://CDS.VizieR/J/AJ/159/246
- Title:
- WIYN open cluster study. LXXX. Photometry of NGC 7142
- Short Name:
- J/AJ/159/246
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present UBVRI photometry of 8702 stars in a 0.5x0.5{deg} field in the direction of NGC7142, taken with the Half Degree Imager at the WIYN 0.9m telescope, to improve knowledge of this cluster's basic parameters. Our photometry spans the ranges 10.6-20.4mag in U, 10.6-22.0mag in B, 10.0-21.8mag in V, 9.2-20.7mag in R, and 8.5-19.9mag in I. Using color-color diagrams that employ all four color combinations that include U, versus B-V, we derive a reddening-metallicity relation for the cluster, with preferred values E(B-V)=0.338{+/-}0.031mag for the left-edge fiducial of the main sequence and [Fe/H]=0.0{+/-}0.1dex, where the Hyades cluster has been used as an unreddened reference cluster, the extinction relations of Cardelli have been employed, and the metallicity dependence of the Yonsei-Yale (Y^2^) isochrones has been assumed. Comparison of our data to the Y^2^ isochrones in multiple color-magnitude diagrams (CMDs) yields distance-metallicity and age-metallicity relations, with preferred values of m-M=12.65{+/-}0.23 mag and age=4.0_+1.3_^-0.7^Gyr. Re-evaluation of the parameters of M67 using Stetson's UBVI photometry yields [Fe/H]=-0.02{+/-}0.05dex, E(B-V)=0.04{+/-}0.01mag, m-M=9.75{+/-}0.03mag, and age=3.85{+/-}0.17Gyr; we thus find the metallicity and age of the two clusters to be indistinguishable. A semi-independent analysis adopting the parameters of M67 and shifting the fiducials of the two clusters in six CMDs until they match strongly corroborates the values listed above. The differences between our inferred parallaxes and the Gaia DR2 values are 87{+/-}60{mu}as for NGC7142 and 48{+/-}15{mu}as for M67, consistent with previous studies.
3596. W3 Main JHKs photometry
- ID:
- ivo://CDS.VizieR/J/A+A/561/A12
- Title:
- W3 Main JHKs photometry
- Short Name:
- J/A+A/561/A12
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Embedded clusters like W3 Main are complex and dynamically evolving systems that represent an important phase in the star formation process. We aim to characterize of the entire stellar content of W3 Main in a statistical sense, which will then identify possible differences in evolutionary phase of the stellar populations and find clues about the formation mechanism of this massive embedded cluster. Deep JHKs imaging is used to derive the disk fraction, Ks-band luminosity functions, and mass functions for several subregions in W3 Main. A two-dimensional completeness analysis using artificial star experiments is applied as a crucial ingredient for assessing realistic completeness limits for our photometry. We find an overall disk fraction of 7.7+/-2.3%, radially varying from 9.4+/-3.0 in the central 1pc to 5.6+/-2.2% in the outer parts of W3 Main. The mass functions derived for three subregions are consistent with a Kroupa and Chabrier mass function. The mass function of IRSN3 is complete down to 0.14M_{sun}_ and shows a break at M~0.5M_{sun}_. We interpret the higher disk fraction in the center as evidence that the cluster center is younger. We find that the evolutionary sequence observed in the low-mass stellar population is consistent with the observed age spread among the massive stars. An analysis of the mass function variations does not show evidence of mass segregation. W3 Main is currently still actively forming stars, showing that the ionizing feedback of OB stars is confined to small areas (~0.5pc). The FUV feedback might be influencing large regions of the cluster as suggested by the low overall disk fraction.
- ID:
- ivo://CDS.VizieR/J/A+A/624/A63
- Title:
- W51 OB stars NIR spectroscopy
- Short Name:
- J/A+A/624/A63
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The interplay between the formation of stars, stellar feedback and cloud properties strongly influences the star formation history of giant molecular clouds. The formation of massive stars leads to a variety of stellar clusters, ranging from low stellar density OB associations to dense, gravitationally bound starburst clusters. We aimed at identifying the massive stellar content and reconstructing the star formation history of the W51 giant molecular cloud. We performed near-infrared imaging and K-band spectroscopy of the massive stars in W51. We analysed the stellar populations using colour-magnitude and colour-colour diagrams and compared the properties of the spectroscopically identified stars with stellar evolution models. We derive the ages of the different sub-clusters in W51 and, based on our spectroscopy derive an age for W51 of 3Myrs or less. The age of the P Cygni star LS1 and the presence of two still forming proto- clusters suggests that the star formation history of W51 is more complex than a single burst. We did not find evidence for triggered star formation and we concluded that the star formation in W51 is multi seeded. We finally concluded that W51 is a OB association where different sub-clusters form over a time span of at least 3-5Myrs.
- ID:
- ivo://CDS.VizieR/J/other/BASI/39.259
- Title:
- WX Pyx J-band light curve
- Short Name:
- J/other/BASI/39.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present near-infrared J-band photometric observations of the intermediate polar WX Pyx. The frequency analysis indicates the presence of a period at 1559.2+/-0.2s which is attributed to the spin period of the white dwarf. The spin period inferred from the infrared data closely matches that determined from X-ray and optical observations. WX Pyx is a system whose orbital period has not been measured directly and which is not too well constrained. From the IR observations, a likely peak at 5.30+/-0.02h is seen in the power spectrum of the object. It is suggested that this corresponds to the orbital period of the system. In case this is indeed the true orbital period, some of the system physical parameters may be estimated. Our analysis indicates that the secondary star is of M2 spectral type and the distance to the object is 1.53kpc. An upper limit of 30 for the angle of inclination of the system is suggested. The mass transfer rate and the magnetic moment of the white dwarf are estimated to be (0.95-1.6)x10^-9^M_{sun}/yr and (1.9-2.4)x10^33^G*cm^3^ respectively.
3599. WZ Cyg BVRI light curves
- ID:
- ivo://CDS.VizieR/J/AJ/142/12
- Title:
- WZ Cyg BVRI light curves
- Short Name:
- J/AJ/142/12
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new multiband CCD photometry for WZ Cyg made on 22 nights in two observing seasons of 2007 and 2008. Our light-curve synthesis indicates that the system is in poor thermal contact with a fill-out factor of 4.8% and a temperature difference of 1447K. Including our 40 timing measurements, a total of 371 times of minimum light spanning more than 112yr were used for a period study. Detailed analysis of the O-C diagram showed that the orbital period has varied by a combination of an upward parabola and a sinusoid.
- ID:
- ivo://CDS.VizieR/J/A+A/568/A5
- Title:
- XDCP J0044.0-2033 J and Ks images
- Short Name:
- J/A+A/568/A5
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Recent observational progress has enabled the detection of galaxy clusters and groups out to very high redshifts and for the first time allows detailed studies of galaxy population properties in these densest environments in what was formerly known as the "redshift desert" at z>1.5. We aim to investigate various galaxy population properties of the massive X-ray luminous galaxy cluster XDCP J0044.0-2033 at z=1.58, which constitutes the most extreme currently known matter-density peak at this redshift. We analyzed deep VLT/HAWK-I near-infrared data with an image quality of 0.5" and limiting Vega magnitudes (50% completeness) of 24.2 in J- and 22.8 in the Ks band, complemented by similarly deep Subaru imaging in i and V, Spitzer observations at 4.5um, and new spectroscopic observations with VLT/FORS 2.
