- ID:
- ivo://CDS.VizieR/J/ApJ/838/107
- Title:
- Distances to RRab stars from WISE and Gaia
- Short Name:
- J/ApJ/838/107
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Pulsating stars, such as Cepheids, Miras, and RR Lyrae stars, are important distance indicators and calibrators of the "cosmic distance ladder," and yet their period-luminosity-metallicity (PLZ) relations are still constrained using simple statistical methods that cannot take full advantage of available data. To enable optimal usage of data provided by the Gaia mission, we present a probabilistic approach that simultaneously constrains parameters of PLZ relations and uncertainties in Gaia parallax measurements. We demonstrate this approach by constraining PLZ relations of type ab RR Lyrae stars in near-infrared W1 and W2 bands, using Tycho-Gaia Astrometric Solution (TGAS) parallax measurements for a sample of ~100 type ab RR Lyrae stars located within 2.5kpc of the Sun. The fitted PLZ relations are consistent with previous studies, and in combination with other data, deliver distances precise to 6% (once various sources of uncertainty are taken into account). To a precision of 0.05mas (1{sigma}), we do not find a statistically significant offset in TGAS parallaxes for this sample of distant RR Lyrae stars (median parallax of 0.8mas and distance of 1.4kpc). With only minor modifications, our probabilistic approach can be used to constrain PLZ relations of other pulsating stars, and we intend to apply it to Cepheid and Mira stars in the near future.
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- ID:
- ivo://CDS.VizieR/J/A+A/486/191
- Title:
- Distances towards 6.7GHz methanol masers
- Short Name:
- J/A+A/486/191
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Distances to most star forming regions are determined using kinematics, through the assumption that the observed radial velocity arises from the motion of the source with respect to the Sun resulting from the differential rotation of Galaxy. The primary challenge associated with the application of this technique in the inner Galaxy is the kinematic distance ambiguity. In this work, we aim to resolve the kinematic distance ambiguity towards a sample of 6.7GHz methanol masers, which are signposts of the early stages of massive star formation. We measured 21cm HI absorption spectra using the Very Large Array in C and CnB configurations. A comparison of the maximum velocity of HI absorption with the source velocity and tangent point velocity was used to resolve the kinematic distance ambiguity.
- ID:
- ivo://CDS.VizieR/J/ApJ/747/50
- Title:
- Distance to Cepheids using the Wesenheit function
- Short Name:
- J/ApJ/747/50
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper, we explore the possibility of using the Wesenheit function to derive individual distances to Galactic Cepheids, as the dispersion of the reddening-free Wesenheit function is smaller than the optical period-luminosity (P-L) relation. When compared to the distances from various methods, the averaged differences between our results and published distances range from -0.061 to 0.009, suggesting that the Wesenheit function can be used to derive individual Cepheid distances. We have also constructed Galactic P-L relations and selected Wesenheit functions based on the derived distances. A by-product from this work is the derivation of Large Magellanic Cloud distance modulus when calibrating the Wesenheit function. It is found to be 18.531+/-0.043 mag.
- ID:
- ivo://CDS.VizieR/J/ApJ/794/107
- Title:
- Distance to NGC6822 with Spitzer/FourStar Photometry
- Short Name:
- J/ApJ/794/107
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a revised distance to the nearby galaxy NGC 6822 using a new multi-band fit to both previously published and new optical, near-, and mid-infrared data for Cepheid variables. The new data presented in this study include multi-epoch observations obtained in 3.6 {mu}m and 4.5 {mu}m with the Spitzer Space Telescope taken for the Carnegie Hubble Program. We also present new observations in J, H, and K_s_ with FourStar on the Magellan Baade Telescope at Las Campanas Observatory. We determine mean magnitudes and present new period-luminosity relations in V, I, J, H, K_s_, Infrared Array Camera 3.6 {mu}m, and 4.5 {mu}m. In addition to using the multi-band distance moduli to calculate extinction and a true distance, we present a new method for determining an extinction-corrected distance modulus from multi-band data with varying sample sizes. We combine the distance moduli and extinction for individual stars to determine E(B-V)=0.35+/-0.04 and a true distance modulus {mu}_o_=23.38+/-0.02_stat_+/-0.04_sys_.
- ID:
- ivo://CDS.VizieR/J/A+A/610/A64
- Title:
- Distance to the clouds in Chamaeleon complex
- Short Name:
- J/A+A/610/A64
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The determination of the distance to dark star-forming clouds is a key parameter to derive the properties of the cloud itself, and of its stellar content. This parameter is still loosely constrained even in nearby star- forming regions. We want to determine the distances to the clouds in the Chamaeleon-Musca complex and to explore the connection between these clouds and the large scale cloud structures in the galaxy. We use the newly estimated distances obtained from the parallaxes measured by the Gaia satellite and included in the Tycho-Gaia Astrometric Solution catalog. When known members of a region are included in this catalog we use their parallaxes to infer the distance to the cloud. Otherwise, we analyze the dependence of the color excess on the distance of the stars and look for a turn-on of this excess, which is a proxy of the position of the front-edge of the star-forming cloud. We are able to measure the distance to the three Chamaeleon clouds. The distance to Chamaeleon I is 179^+11+11^_-10-10_pc, where the quoted uncertainties are statistical and systematic uncertainties, respectively, 20 pc further away than previously assumed. The Chamaeleon II cloud is located at the distance of 181^+6+11^_-5-10_pc, which agrees with previous estimates. We are able to measure for the first time a distance to the Chamaeleon III cloud of 199^+8+12^_-7-11_pc. Finally, the distance of the Musca cloud is smaller than 603^+91+133^_-70-92_pc. These estimates do not allow us to distinguish between the possibility that the Chamaeleon clouds are part of a sheet of clouds parallel to the galactic plane, or perpendicular to it. We have measured a larger distance to the Chamaeleon I cloud than assumed in the past, confirmed the distance to the Chamaeleon II region, and measured for the first time the distance to the Chamaleon III cloud. These values are consistent with the scenario where the three clouds are part of a single large scale structure. Gaia Data Release 2 will allow us to put more stringent constraints on the distances to these clouds by giving us access to parallax measurements for a larger number of members of these regions.
- ID:
- ivo://CDS.VizieR/J/MNRAS/361/109
- Title:
- Distant cluster galaxies Tully-Fisher relation
- Short Name:
- J/MNRAS/361/109
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have measured maximum rotation velocities (Vrot) for a sample of 111 emission-line galaxies with 0.1~<z~<1, observed in the fields of six clusters. From these data we construct 'matched' samples of 58 field and 22 cluster galaxies, covering similar ranges in redshift (0.25<=z<=1.0) and luminosity (M_B_<=-19.5mag), and selected in a homogeneous manner.
- ID:
- ivo://CDS.VizieR/J/ApJ/569/689
- Title:
- Distant cluster hunting. II.
- Short Name:
- J/ApJ/569/689
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present and analyze the optical and X-ray catalogs of moderate-redshift cluster candidates from the ROSAT Optical X-Ray Survey, or ROXS. The survey covers the sky area contained in the fields of view of 23 deep archival ROSAT PSPC pointings, 4.8 square degrees. The cross-correlated cluster catalogs were constructed by comparing two independent catalogs extracted from the optical and X-ray bandpasses, using a matched-filter technique for the optical data and a wavelet technique for the X-ray data. We cross-identified cluster candidates in each catalog.
- ID:
- ivo://CDS.VizieR/J/A+A/607/A56
- Title:
- Distant clusters of galaxies in the 2XMM/SDSS
- Short Name:
- J/A+A/607/A56
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Galaxy clusters at high redshift are important to test cosmological models and models for the growth of structure. They are difficult to find in wide-angle optical surveys, however, leaving dedicated follow-up of X-ray selected candidates as one promising identification route. We aim to increase the number of galaxy clusters beyond the SDSS-limit, z~0.75. We compiled a list of extended X-ray sources from the 2XMMp catalogue within the footprint of the Sloan Digital Sky Survey. Fields without optical counterpart were selected for further investigation. Deep optical imaging and follow-up spectroscopy were obtained with the Large Binocular Telescope, Arizona (LBT), of those candidates not known to the literature. From initially 19 candidates, selected by visually screening X-ray images of 478 XMM-Newton observations and the corresponding SDSS images, 6 clusters were found in the literature. Imaging data through r,z filters were obtained for the remaining candidates, and 7 were chosen for multi-object (MOS) spectroscopy. Spectroscopic redshifts, optical magnitudes, and X-ray parameters (flux, temperature, and luminosity) are presented for the clusters with spectroscopic redshifts. The distant clusters studied here constitute one additional redshift bin for studies of the L-T relation, which does not seem to evolve from high to low redshifts. The selection method of distant galaxy clusters presented here was highly successful. It is based solely on archival optical (SDSS) and X-ray (XMM-Newton) data. Out of 19 selected candidates, 6 of the 7 candidates selected for spectroscopic follow-up were verified as distant clusters, a further candidate is most likely a group of galaxies at z~1.21. Out of the remaining 12 candidates, 6 were known previously as galaxy clusters, one object is a likely X-ray emission from an AGN radio jet, and for 5 we see no clear evidence for them to be high-redshift galaxy clusters.
- ID:
- ivo://CDS.VizieR/J/ApJ/672/930
- Title:
- Distant CO clouds in third galactic quadrant
- Short Name:
- J/ApJ/672/930
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We combine optical and radio observations to trace the spiral structure in the third quadrant of the Milky Way. The optical observations consist of a large sample of young open clusters and associations, whereas the radio observations consist of a survey of nearby and distant clouds observed in CO. Both the optical and radio samples are the largest ones thus far presented in the literature. We use this unique material to analyze the behavior of interstellar extinction and to trace the detailed structure of the third Galactic quadrant (TGQ).
- ID:
- ivo://CDS.VizieR/J/AJ/125/1660
- Title:
- Distant compact groups from DPOSS
- Short Name:
- J/AJ/125/1660
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have identified 84 small, high-density groups of galaxies out to z~0.2 in a region of 2000deg^2^ around the north Galactic pole using the digitized Second Palomar Observatory Sky Survey. The groups have at least four galaxies satisfying more stringent criteria than those used by Hickson in his pioneering work in 1982: the adopted limiting surface brightness for each group is brighter (24mag/arcsec^2^ instead of 26mag/arcsec^2^), and the spread in magnitude among the member galaxies is narrower (2mag instead of 3). We also adopt a slightly modified version of the isolation criterion used by Hickson, in order to avoid rejecting groups with projected nearby faint background galaxies. A 10% contamination rate due to projection effects is expected for this sample based on extensive simulations.