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8211. WISE reduced proper motions and spectral types
ID:
ivo://CDS.VizieR/J/ApJ/787/126
Title:
WISE reduced proper motions and spectral types
Short Name:
J/ApJ/787/126
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present an analysis of high proper motion objects that we have found in a recent study and in this work with multi-epoch astrometry from the Wide-field Infrared Survey Explorer (WISE). Using photometry and proper motions from the Two Micron All-Sky Survey and WISE, we have identified the members of this sample that are likely to be late-type, nearby, or metal-poor. We have performed optical and near-infrared spectroscopy on 41 objects, from which we measure spectral types that range from M4-T2.5. This sample includes 11 blue L dwarfs and 5 subdwarfs; the latter were also classified as such in the recent study by Kirkpatrick and coworkers. Based on their spectral types and photometry, several of our spectroscopic targets may have distances of <20 pc with the closest at ~12 pc. The tangential velocities implied by the spectrophotometric distances and proper motions indicate that four of the five subdwarfs are probably members of the Galactic halo while several other objects, including the early-T dwarf WISE J210529.08-623558.7, may belong to the thick disk.
8212. WISE-selected candidate SFRs beyond the Outer Arm
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.
8213. WISE view of RV Tauri stars
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.
8214. WISE YSO candidates near {sigma} and {lambda} Ori
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.
8215. 2001-2006 WIYN binary stars speckle observations
ID:
ivo://CDS.VizieR/J/AJ/136/312
Title:
2001-2006 WIYN binary stars speckle observations
Short Name:
J/AJ/136/312
Date:
21 Oct 2021
Publisher:
CDS
Description:
A total of 1067 speckle observations of 345 binary stars are presented. Of these, 161 are double stars first resolved by Hipparcos, 17 are resolved for the first time in the observations presented here, and 21 are stars previously discovered by our program and reported in earlier papers in the series. In 947 cases, a magnitude difference is reported along with the relative astrometry.
8216. WIYN Open Cluster. LXI. NGC 6819 photometry
ID:
ivo://CDS.VizieR/J/AJ/148/51
Title:
WIYN Open Cluster. LXI. NGC 6819 photometry
Short Name:
J/AJ/148/51
Date:
21 Oct 2021
Publisher:
CDS
Description:
NGC 6819 is a richly populated, older open cluster situated within the Kepler field. A CCD survey of the cluster on the uvbyCaH{beta} system, coupled with proper-motion membership, has been used to isolate 382 highly probable, single-star unevolved main-sequence members over a 20' field centered on the cluster. From 278 F dwarfs with high precision photometry in all indices, a mean reddening of E(b-y)=0.117+/-0.005 or E(B-V)=0.160+/-0.007 is derived, where the standard errors of the mean include both internal errors and the photometric zero-point uncertainty. With the reddening fixed, the metallicity derived from the same 278 stars is [Fe/H]=-0.116+/-0.101 from m_1_ and -0.055+/-0.033 from hk, for a weighted average of [Fe/H]=-0.06+/-0.04, where the quoted standard errors of the mean include the internal errors from the photometric scatter plus the uncertainty in the photometric zero points. If metallicity is derived using individual reddening values for each star to account for potential reddening variation across the face of the cluster, the analogous result is unchanged. The cluster members at the turnoff of the color-magnitude diagram are used to test and confirm the recently discovered variation in reddening across the face of the cluster, with a probable range in the variation of {Delta}E(B-V)=0.045+/-0.015. With the slightly higher reddening and lower [Fe/H] compared to commonly adopted values, isochrone fitting leads to an age of 2.3+/-0.2Gyr for an apparent modulus of (m-M)=12.40+/-0.12.
8217. WIYN open cluster study. LV. NGC 6819
ID:
ivo://CDS.VizieR/J/AJ/146/43
Title:
WIYN open cluster study. LV. NGC 6819
Short Name:
J/AJ/146/43
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present proper motions and astrometric membership analysis for 15750 stars around the intermediate-age open cluster NGC 6819. The accuracy of relative proper motions for well-measured stars ranges from ~0.2mas/yr within 10' of the cluster center to 1.1mas/yr outside this radius. In the proper motion vector-point diagram, the separation between the cluster members and field stars is convincing down to V~18 and within 10' from the cluster center. The formal sum of membership probabilities indicates a total of ~2500 cluster members down to V~22. We confirm the cluster membership of several variable stars, including some eclipsing binaries. The estimated absolute proper motion of NGC 6819 is {mu}_x_^abs^=-2.6+/-0.5 and {mu}_y_^abs^=-4.2+/-0.5mas/yr. A cross-identification between the proper motion catalog and a list of X-ray sources in the field of NGC 6819 resulted in a number of new likely optical counterparts, including a candidate CV. For the first time we show that there is significant differential reddening toward NGC 6819.
8218. WIYN open cluster study. LXII. Photometry of M35
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.
8219. WIYN open cluster study. LXXX. Photometry of NGC 7142
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.
8220. 2007-2008 WIYN speckle observations of binaries
ID:
ivo://CDS.VizieR/J/AJ/139/205
Title:
2007-2008 WIYN speckle observations of binaries
Short Name:
J/AJ/139/205
Date:
21 Oct 2021
Publisher:
CDS
Description:
Results of 974 speckle observations of 546 binary stars are presented. Observations were obtained at the WIYN 3.5m Telescope at Kitt Peak National Observatory during the time interval from 2007 January to 2008 June. In all cases, the relative separation and position angle of the components are measured, and the magnitude difference is determined in 809 cases. The precision of the results as judged from repeat observations and objects with very well-determined orbits is similar to previous papers in this series, namely ~3mas in separation and <1{deg} in position angle in most cases. Similarly, the photometric precision remains consistent with previous WIYN speckle data, on average ~0.1mag per observation. Six systems of special interest are discussed.