- ID:
- ivo://CDS.VizieR/J/ApJ/867/12
- Title:
- Mass-richness relations for X-ray and SZE clusters
- Short Name:
- J/ApJ/867/12
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the mass-richness relation of 116 spectroscopically confirmed massive clusters at 0.4<z<2 by mining the Spitzer archive. We homogeneously measure the richness at 4.5um for our cluster sample within a fixed aperture of 2' radius and above a fixed brightness threshold, making appropriate corrections for both background galaxies and foreground stars. We have two subsamples, those which have (a) literature X-ray luminosities and (b) literature Sunyaev-Zel'dovich effect masses. For the X-ray subsample we re-derive masses adopting the most recent calibrations. We then calibrate an empirical mass-richness relation for the combined sample spanning more than one decade in cluster mass and find the associated uncertainties in mass at fixed richness to be +/-0.25dex. We study the dependence of the scatter of this relation with galaxy concentration, defined as the ratio between richness measured within an aperture radius of 1' and 2'. We find that at fixed aperture radius the scatter increases for clusters with higher concentrations. We study the dependence of our richness estimates with depth of the 4.5um imaging data and find that reaching a depth of at least [4.5]=21(AB)mag is sufficient to derive reasonable mass estimates. We discuss the possible extension of our method to the mid-infrared WISE All Sky Survey data and the application of our results to the Euclid mission. This technique makes richness-based cluster mass estimates available for large samples of clusters at very low observational cost.
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Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/126/2421
- Title:
- 2MASS-Selected sample of ultracool dwarfs
- Short Name:
- J/AJ/126/2421
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the initial results of our effort to create a statistically robust, volume-limited sample of ultracool dwarfs from the Two Micron All Sky Survey Second Incremental Data Release (<II/241>). We are engaged in a multifaceted search for nearby late-type objects, and this is the first installment of our search using purely photometric selection. The goal of this work is a determination of the low-mass star and brown dwarf luminosity function in the infrared. Here we outline the construction of the sample, dubbed 2MU2, and present our first results, including the discovery of 186 M7-L6 dwarfs, 47 of which are likely to be within 20pc of the Sun. These results represent 66% of the ultracool candidates in our sample yet constitute a 127% increase in the number of ultracool dwarfs known within the volume searched (covering 40% of the sky out to 20pc). In addition, we have identified 10 M4-M6.5 objects that are likely to be within 20pc (or within 1{sigma}). Finally, based on these initial data, we present a preliminary luminosity function and discuss several interesting features of the partial sample presented here. Once our sample is complete, we will use our measured luminosity function to constrain the mass function of low-mass stars and brown dwarfs.
- ID:
- ivo://CDS.VizieR/J/MNRAS/475/343
- Title:
- 2MASS, WISE, and SuperCOSMOS clusters of galaxies
- Short Name:
- J/MNRAS/475/343
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We identify 47600 clusters of galaxies from photometric data of Two Micron All Sky Survey (2MASS), Wide-field Infrared Survey Explorer (WISE), and SuperCOSMOS, among which 26125 clusters are recognized for the first time and mostly in the sky outside the Sloan Digital Sky Survey (SDSS) area. About 90 per cent of massive clusters of M_500_>3x10^14^M_{sun}_ in the redshift range of 0.025<z<0.3 have been detected from such survey data, and the detection rate drops down to 50 per cent for clusters with a mass of M_500_~1x10^14^M_{sun}_. Monte Carlo simulations show that the false detection rate for the whole cluster sample is less than 5 per cent. By cross-matching with ROSAT and XMM-Newton sources, we get 779 new X-ray cluster candidates which have X-ray counterparts within a projected offset of 0.2Mpc.
- ID:
- ivo://CDS.VizieR/II/281
- Title:
- 2MASS 6X Point Source Working Database / Catalog
- Short Name:
- II/281
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A special set of observations that utilized exposure times six times longer than the main 2MASS survey measurements were conducted in the final year of 2MASS observatory operations. The 2MASS "6x" observations achieved sensitivities ~1 mag deeper than the main 2MASS survey, and covered approximately 590 deg2 of sky in 30 discrete regions. The 2MASS 6x Point Source Working Databases (6x-PSWDB and 6x-XSWDB) contain all detections extracted from the raw 6x imaging data during pipeline data reduction. The 6x WDB entries include reliable detections of astrophysical sources, as well as spurious detections of noise excursions, image artifacts and transient events such as meteor trails, cosmic rays and hot pixels. In addition, the WDBs may contain multiple, independent detections of objects scanned more than once during the 6x observations. The 2MASS 6x Point Source Catalogs (6x-PSC and 6x-XSC) is a subset of extractions in the 6x-PSWDB that have been identified to be high reliability source detections, with only one measurement of sources detected multiple times for uniformity.
- ID:
- ivo://CDS.VizieR/J/A+A/618/A137
- Title:
- MC cool supergiants spectra
- Short Name:
- J/A+A/618/A137
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This atlas composed by more than 1500 spectra of late-type stars (spectral types from G to M) observed simultaneously in the optical and Calcium Triplet spectral ranges. These spectra were obtained as part of a survey to search for cool supergiants in the Magellanic Clouds and taken over four epochs. We provide the spectral and luminosity classification for each spectrum (71% are supergiants, 13% are giants or luminous giants, 4% are Carbon or S~Stars and the remaining 12% are foreground stars of lesser luminosities).
- ID:
- ivo://CDS.VizieR/J/ApJ/745/156
- Title:
- M31 Cepheids with HST/WFC3
- Short Name:
- J/ApJ/745/156
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present measurements of 68 classical Cepheids, most detected from the Canada-France-Hawaii Telescope POMME Survey, with periods from 10 to 78 days observed in the near-infrared by the Panchromatic Hubble Andromeda Treasury Program using the Wide Field Camera 3 (WFC3) on the Hubble Space Telescope (HST). The combination of HST's resolution and the use of near-infrared measurements provide a dramatic reduction in the dispersion of the period-luminosity relation over the present optical, ground-based data. Even using random phase magnitudes we measure a dispersion of just 0.17mag, implying a dispersion of just 0.12mag for mean magnitudes. The error in the mean for this relation is 1% in distance. Combined with similar observations of Cepheids in other hosts and independent distance determinations, we measure a distance to M31 of {mu}_0_=24.38+/-0.06(statistical)+/-0.03(systematic), 752+/-27kpc, in good agreement with past measurements though with a better, 3% precision here. The result is also in good agreement with independent distance determinations from two detached eclipsing binaries allowing for an independent calibration of the Cepheid luminosities and a determination of the Hubble constant.
- ID:
- ivo://CDS.VizieR/J/AJ/159/52
- Title:
- M dwarfs at high spectral-resolution in Y band
- Short Name:
- J/AJ/159/52
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In young Sun-like stars and field M-dwarf stars, chromospheric and coronal magnetic activity indicators such as H{alpha}, X-ray, and radio emission are known to saturate with low Rossby number (Ro<~0.1), defined as the ratio of rotation period to convective turnover time. The mechanism for the saturation is unclear. In this paper, we use photospheric TiI and CaI absorption lines in the Y band to investigate magnetic field strength in M dwarfs for Rossby numbers between 0.01 and 1.0. The equivalent widths of the lines are magnetically enhanced by photospheric spots, a global field, or a combination of the two. The equivalent widths behave qualitatively similar to the chromospheric and coronal indicators: we see increasing equivalent widths (increasing absorption) with decreasing Ro and saturation of the equivalent widths for Ro<~0.1. The majority of M dwarfs in this study are fully convective. The results add to mounting evidence that the magnetic saturation mechanism occurs at or beneath the stellar photosphere.
- ID:
- ivo://CDS.VizieR/J/A+A/640/A52
- Title:
- M dwarfs HeI infrared triplet variability
- Short Name:
- J/A+A/640/A52
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The HeI infrared (IR) triplet at 10830{AA} is an important activity indicator for the Sun and in solar-type stars, however, it has rarely been studied in relation to M dwarfs to date. In this study, we use the time-averaged spectra of 319 single stars with spectral types ranging from M0.0 V to M9.0V obtained with the CARMENES high resolution optical and near-infrared spectrograph at Calar Alto to study the properties of the HeI IR triplet lines. In quiescence, we find the triplet in absorption with a decrease of the measured pseudo equivalent width (pEW) towards later sub-types. For stars later than M5.0 V, the HeI triplet becomes undetectable in our study. This dependence on effective temperature may be related to a change in chromospheric conditions along the Mdwarf sequence. When an emission in the triplet is observed, we attribute it to flaring. The absence of emission during quiescence is consistent with line formation by photo-ionisation and recombination, while flare emission may be caused by collisions within dense material. The HeI triplet tends to increase in depth according to increasing activity levels, ultimately becoming filled in; however, we do not find a correlation between the pEW(He IR) and X-ray properties. This behaviour may be attributed to the absence of very inactive stars (LX/Lbol<-5.5) in our sample or to the complex behaviour with regard to increasing depth and filling in.
- ID:
- ivo://CDS.VizieR/J/A+A/542/A33
- Title:
- 3 M dwarfs near-infrared spectra
- Short Name:
- J/A+A/542/A33
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The relatively large spread in the derived metallicities ([Fe/H]) of M dwarfs shows that various approaches have not yet converged to consistency. The presence of strong molecular features, and incomplete line lists for the corresponding molecules have made metallicity determinations of M dwarfs difficult. Furthermore, the faint M dwarfs require long exposure times for a signal-to-noise ratio sufficient for a detailed spectroscopic abundance analysis. We present a high-resolution (R~50000) spectroscopic study of a sample of eight single M dwarfs and three wide-binary systems observed in the infrared J-band.
- ID:
- ivo://CDS.VizieR/J/ApJ/802/L10
- Title:
- M dwarf SpeX NIR spectroscopy
- Short Name:
- J/ApJ/802/L10
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Despite the ubiquity of M dwarfs and their growing importance to studies of exoplanets, Galactic evolution, and stellar structure, methods for precisely measuring their fundamental stellar properties remain elusive. Existing techniques for measuring M dwarf luminosity, mass, radius, or composition are calibrated over a limited range of stellar parameters or require expensive observations. We find a strong correlation between the K_S_-band luminosity (M_K_), the observed strength of the I-band sodium doublet absorption feature, and [Fe/H] in M dwarfs without strong H{alpha} emission. We show that the strength of this feature, coupled with [Fe/H] and spectral type, can be used to derive M dwarf M_K_ and radius without requiring parallax. Additionally, we find promising evidence that the strengths of the I-band sodium doublet and the nearby I-band calcium triplet may jointly indicate {alpha}-element enrichment. The use of these I-band features requires only moderate-resolution near-infrared spectroscopy to provide valuable information about the potential habitability of exoplanets around M dwarfs, and surface gravity and distance for M dwarfs throughout the Galaxy. This technique has immediate applicability for both target selection and candidate planet-host system characterization for exoplanet missions such as TESS and K2.
