- ID:
- ivo://CDS.VizieR/J/AJ/160/169
- Title:
- WOCS. LXXXII. Orbital parameters & RVs in NGC 7789
- Short Name:
- J/AJ/160/169
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an extensive time-series radial-velocity (RV) survey of stars in the rich open cluster NGC7789 (1.6Gyr, [Fe/H]=+0.02). The stellar sample lies within an 18' circular radius from the cluster center (10pc in projection, or about 2core radii), and includes giants, red clump stars, blue stragglers, red stragglers, sub-subgiants, and main-sequence stars down to 1mag below the turnoff. Our survey began in 2005 and comprises more than 9000 RV measurements from the Hydra Multi-Object Spectrograph on the WIYN 3.5m telescope. We identify 624 likely cluster members and present the orbital solutions for 81 cluster binary stars with periods between 1.45 and 4200days. From the main-sequence binary solutions we fit a circularization period of 7.2_-1.1_^+0.6^days. We calculate an incompleteness-corrected main- sequence binary frequency of 31%{+/-}4% for binaries with periods less than 104days, similar to other WIYN Open Cluster Survey (WOCS) open clusters of all ages. We detect a blue straggler binary frequency of 33%{+/-}17%, consistent with the similarly aged open cluster NGC6819. We also find one secure, rapidly rotating sub-subgiant and one red straggler candidate in our sample.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+AS/124/205
- Title:
- W3 star-forming region 345 GHz survey
- Short Name:
- J/A+AS/124/205
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Results are presented of the 345 GHz spectral survey toward three sources in the W 3 Giant Molecular Cloud: W 3 IRS4, W 3 IRS5 and W 3(H_2_O). Nearly 90% of the atmospheric window between 334 and 365GHz has been scanned using the James Clerk Maxwell Telescope (JCMT) down to a noise level of ~80mK per resolution element. These observations are complemented by a large amount of data in the 230GHz atmospheric window. From this data set physical conditions and beam-averaged column densities are derived for more than 14 chemically different species (over 24 different isotopes). The physical parameters derived in Paper I (Helmich et al., 1994A&A...283..626H) are confirmed by the analysis of the excitation of other species, although there is evidence that the silicon- and sulfur-bearing molecules exist in a somewhat denser and warmer environment. The densities are high, >=10^6^cm^-3^, in the three sources and the kinetic temperatures for the bulk of the gas range from 55K for IRS4 to 220K for W 3(H_2_O). The chemical differences between the three sources are very striking: silicon- and sulfur-bearing molecules such as SiO and SO_2_ are prominent toward IRS5, whereas organic molecules like CH_3_OH, CH_3_OCH_3_ and CH_3_OCHO are at least an order of magnitude more abundant toward W 3(H_2_O). Vibrationally excited molecules are also detected toward this source. Only simple molecules are found toward IRS4. The data provide constraints on the amount of deuterium fractionation and the ionization fraction in the observed regions as well. These chemical characteristics are discussed in the context of an evolutionary sequence, in which IRS5 is the youngest, W 3(H_2_O) somewhat older and IRS4, although still enigmatic, the oldest.
- ID:
- ivo://CDS.VizieR/J/ApJS/184/138
- Title:
- XID II: RASS/BSC-2MASS/PSC cross-association
- Short Name:
- J/ApJS/184/138
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The 18806 ROSAT All Sky Survey Bright Source Catalog (RASS/BSC) X-ray sources are quantitatively cross-associated with near-infrared (NIR) sources from the Two Micron All Sky Survey Point Source Catalog (2MASS/PSC). An association catalog is presented, listing the most likely counterpart for each RASS/BSC source, the probability Pid that the NIR source and X-ray source are uniquely associated, and the probability Pno-id that none of the 2MASS/PSC sources are associated with the X-ray source. The catalog includes 3853 high quality (Pid>0.98) X-ray-NIR matches, 2280 medium quality (0.98>=Pid>0.9) matches, and 4153 low quality (0.9>=Pid>0.5) matches. Of the high quality matches, 1418 are associations that are not listed in the SIMBAD database, and for which no high quality match with a USNO-A2 optical source was presented for the RASS/BSC source in previous work. The present work offers a significant number of new associations with RASS/BSC objects that will require optical/NIR spectroscopy for classification. For example, of the 6133 Pid>0.9 2MASS/PSC counterparts presented in the association catalog, 2411 have no classification listed in the SIMBAD database. These 2MASS/PSC sources will likely include scientifically useful examples of known source classes of X-ray emitters (white dwarfs, coronally active stars, active galactic nuclei), but may also contain previously unknown source classes. It is determined that all coronally active stars in the RASS/BSC should have a counterpart in the 2MASS/PSC, and that the unique association of these RASS/BSC sources with their NIR counterparts thus is confusion limited.
- ID:
- ivo://CDS.VizieR/J/MNRAS/449/1422
- Title:
- 2XMM AGN X-ray and mid-IR luminosities
- Short Name:
- J/MNRAS/449/1422
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have determined the relation between the AGN luminosities at rest-frame 6{mu}m associated with the dusty torus emission and at 2-10keV energies using a complete, X-ray-flux-limited sample of 232 AGN drawn from the Bright Ultra-hard XMM-Newton Survey. The objects have intrinsic X-ray luminosities between 10^42^ and 10^46^erg/s and redshifts from 0.05 to 2.8. The rest-frame 6{mu}m luminosities were computed using data from the Wide-field Infrared Survey Explorer and are based on a spectral energy distribution decomposition into AGN and galaxy emission. The best-fitting relationship for the full sample is consistent with being linear, L_6{mu}m_{prop.to}L_2-10keV_^0.99+/-0.03^, with intrinsic scatter, {Delta}logL_6{mu}m_~0.35dex. The L_6{mu}m_/L_2-10keV_ luminosity ratio is largely independent of the line-of-sight X-ray absorption. Assuming a constant X-ray bolometric correction, the fraction of AGN bolometric luminosity reprocessed in the mid-IR decreases weakly, if at all, with the AGN luminosity, a finding at odds with simple receding torus models. Type 2 AGN have redder mid-IR continua at rest-frame wavelengths <12{mu}m and are overall ~1.3-2 times fainter at 6{mu}m than type 1 AGN at a given X-ray luminosity. Regardless of whether type 1 and type 2 AGN have the same or different nuclear dusty toroidal structures, our results imply that the AGN emission at rest-frame 6{mu}m is not isotropic due to self-absorption in the dusty torus, as predicted by AGN torus models. Thus, AGN surveys at rest-frame ~6{mu}m are subject to modest dust obscuration biases.
- ID:
- ivo://CDS.VizieR/J/MNRAS/362/1065
- Title:
- XMM/Chandra study of IC 10
- Short Name:
- J/MNRAS/362/1065
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an X-ray study of our nearest starburst galaxy IC 10, based on XMM-Newton and Chandra observations. A list of 73 XMM-Newton and 28 Chandra detections of point-like X-ray sources in the field is provided; a substantial fraction of them are likely stellar objects in the Milky Way due to the low Galactic latitude location of IC 10.
- ID:
- ivo://CDS.VizieR/J/ApJ/815/129
- Title:
- X-ray AGNs with Subaru/FMOS NIR observations
- Short Name:
- J/ApJ/815/129
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the Eddington ratio distribution of X-ray-selected broad-line active galactic nuclei (AGNs) in the redshift range 1.0<z<2.2, where the number density of AGNs peaks. Combining the optical and Subaru/Fiber Multi Object Spectrograph near-infrared spectroscopy, we estimate black hole masses for broad-line AGNs in the Chandra Deep Field South (CDF-S), Extended Chandra Deep Field South (E-CDF-S), and the XMM-Newton Lockman Hole (XMM-LH) surveys. AGNs with similar black hole masses show a broad range of AGN bolometric luminosities, which are calculated from X-ray luminosities, indicating that the accretion rate of black holes is widely distributed. We find a substantial fraction of massive black holes accreting significantly below the Eddington limit at z<~2, in contrast to what is generally found for luminous AGNs at high redshift. Our analysis of observational selection biases indicates that the "AGN cosmic downsizing" phenomenon can be simply explained by the strong evolution of the comoving number density at the bright end of the AGN luminosity function, together with the corresponding selection effects. However, one might need to consider a correlation between the AGN luminosity and the accretion rate of black holes, in which luminous AGNs have higher Eddington ratios than low-luminosity AGNs, in order to understand the relatively small fraction of low-luminosity AGNs with high accretion rates in this epoch. Therefore, the observed downsizing trend could be interpreted as massive black holes with low accretion rates, which are relatively fainter than less-massive black holes with efficient accretion.
- ID:
- ivo://CDS.VizieR/J/AJ/132/1100
- Title:
- X-ray and IR sources in RCW 38
- Short Name:
- J/AJ/132/1100
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on results of a 96.7ks Chandra observation of one of the youngest, most embedded, and most massive young stellar clusters studied in X-rays: RCW 38. We detect 460 sources in the field, of which 360 are confirmed to be associated with the RCW 38 cluster. The cluster members range in luminosity from 10^30^ to 10^33.5^ergs/s. Over 10% of the cluster members with over 100 counts exhibit flares, while about 15% of the cluster members with over 30 counts are variable. Of the sources identified as cluster members, 160 have near-infrared (NIR) counterparts either in the Two Micron All Sky Survey database or detected via Very Large Telescope observations. Of these, about 20% appear to have optically thick disks. An additional 353 members are identified through NIR observations, of which at least 50% possess optically thick disks. We fit over 100 X-ray sources as absorbed Raymond-Smith-type plasmas and find that the column to the cluster members varies from 10^21.5^ to 10^23^cm^-2^. We compare the gas to dust absorption signatures in these stars and find NH=A_V_(2x10^21^)cm^-2^. We find that the cluster contains 31 candidate OB stars and is centered about 10" (0.1pc) west of the primary source of the ionization, the O5 star IRS 2. The cluster has a peak central density of about 400 X-ray sources/pc^2^. We estimate that the total cluster membership exceeds 2000 stars.
- ID:
- ivo://CDS.VizieR/J/A+A/359/113
- Title:
- X-ray and IR study of Rho Oph dark cloud
- Short Name:
- J/A+A/359/113
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have obtained two deep exposures of the {rho} Oph cloud core region with the ROSAT High Resolution Imager. The improved position accuracy (1"-6") with respect to previous recent X-ray observations (ROSAT PSPC, and ASCA) allows us to remove positional ambiguities for the detected sources. We also cross-correlate the X-ray positions with IR sources found in the ISOCAM survey of the same region at 6.7 and 14.3{mu}m, in addition to sources (optical and IR) known from ground-based observations, which are young stars (T Tauri stars, with and without circumstellar disks, and protostars). We thus obtain the best-studied sample of X-ray emitting stars in a star-forming region (63 X-ray sources detected, and 55 identified).
- ID:
- ivo://CDS.VizieR/J/AJ/130/2212
- Title:
- X-ray and NIR studies of L1448
- Short Name:
- J/AJ/130/2212
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of X-ray and near-infrared (NIR) observations of L1448, a star-forming region in the Perseus cloud complex using the Chandra X-Ray Observatory and the 4m telescope at the Kitt Peak National Observatory. We detect 72 X-ray sources in a ~17'x17' region with a 68 ks ACIS exposure down to the X-ray flux limit of ~10^-15^ergs/s/cm2 (0.5-8keV), for which we conduct follow-up NIR imaging observations in a concentric ~11'x11' region with FLAMINGOS down to mi_Ks_~17mag. Twelve X-ray sources have NIR or optical counterparts.
- ID:
- ivo://CDS.VizieR/J/ApJ/613/393
- Title:
- X-ray and radio sources in {rho} Oph Core A
- Short Name:
- J/ApJ/613/393
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A 96ks Chandra X-ray observation of {rho} Ophiuchus cloud core A detected 87 sources, of which 60 were identified with counterparts at other wavelengths. Simultaneous multifrequency Very Large Array (VLA) observations detected 31 radio sources at 6cm, of which 10 were also detected by Chandra. We report new radio detections of the optically invisible IR source WLY 2-11 and the faint H{alpha} emission line star Elias 24 (class II).
