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3971. Mid-IR photometry of cold brown dwarfs
ID:
ivo://CDS.VizieR/J/ApJ/710/1627
Title:
Mid-IR photometry of cold brown dwarfs
Short Name:
J/ApJ/710/1627
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present new Spitzer Infrared Array Camera (IRAC) photometry of 12 very late-type T dwarfs: nine have [3.6], [4.5], [5.8], and [8.0] photometry and three have [3.6] and [4.5] photometry only. Combining this with previously published photometry, we investigate trends with type and color that are useful for both the planning and interpretation of infrared surveys designed to discover the coldest T or Y dwarfs. The online appendix provides a collation of MKO-system YJHKL'M' and IRAC photometry for a sample of M, L, and T dwarfs. There are 12 dwarfs currently known with H-[4.5]>3.0, and 500K<~T_eff_<~800K, which we examine in detail. The ages of the dwarfs in the sample range from very young (0.1-1.0Gyr) to relatively old (3-12Gyr). The mass range is possibly as low as 5 Jupiter masses to up to 70 Jupiter masses, i.e., near the hydrogen burning limit. The metallicities also span a large range, from [m/H]=-0.3 to [m/H]=+0.3.
3972. Mid-IR properties of OH maser galaxies
ID:
ivo://CDS.VizieR/J/A+A/570/A110
Title:
Mid-IR properties of OH maser galaxies
Short Name:
J/A+A/570/A110
Date:
21 Oct 2021
Publisher:
CDS
Description:
We compiled all 119 OH maser galaxies (110 out of them are megamasers, i.e., L_OH_>10L_{sun}_) published so far and cross-identified these OH masers with the Wide-Field Infrared Survey Explorer (WISE) catalog, to investigate the middle infrared (MIR) properties of OH maser galaxies. The WISE magnitude data at the 3.4, 4.6, 12 and 22{mu}m (W1 to W4) are collected for the OH maser sample and one control sample, which are non-detection sources. The color-color diagrams show that both OH megamaser (OHM) and non-OHM (ultra)luminous infrared galaxies ((U)LIRGs) are far away from the single blackbody model line and many of them can follow the path described by the power-law model. The active galaxy nuclei (AGN) fraction is about ~40% for both OHM and non-OHM (U)LIRGs, according to the AGN criteria W1-W2>=0.8. Among the Arecibo survey sample, OHM sources tend to have a lower luminosity at short MIR wavelengths (e.g., 3.4{mu}m and 4.6{mu}m) than that of non-OHM sources, which should come from the low OHM fraction among the survey sample with large 3.4{mu}m and 4.6{mu}m luminosity. The OHM fraction tends to increase with cooler MIR colors (larger F_22{mu}m_/F_3.4{mu}m_). These may be good for sample selection when searching OH megamasers, such as excluding extreme luminous sources at short MIR wavelengths, choosing sources with cooler MIR colors. In the case of the power-law model, we derived the spectral indices for our samples. For the Arecibo survey sample, OHM (U)LIRGs tend to have larger spectral index {alpha}_22-12_ than non-OHM sources, which agrees with previous results. One significant correlation exists between the WISE infrared luminosity at 22{mu}m and the color [W1]-[W4] for the Arecibo OHM hosts. These clues should provide suitable constraints on the sample selection for OH megamaser surveys by future advanced telescopes (e.g., FAST). In addition, the correlation of maser luminosity and the MIR luminosity of maser hosts tends to be non-significant, which may indirectly support the pumping of OHM emission that is dominated by the far infrared radiation, instead of the MIR radiation.
3973. Mid-IR sources in EGS
ID:
ivo://CDS.VizieR/J/ApJS/177/431
Title:
Mid-IR sources in EGS
Short Name:
J/ApJS/177/431
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Extended Groth Strip (EGS) is one of the premier fields for extragalactic deep surveys. Deep observations of the EGS with the Infrared Array Camera (IRAC) on the Spitzer Space Telescope cover an area of 0.38deg^2^ to a 50% completeness limit of 1.5uJy at 3.6um. The catalog comprises 57434 objects detected at 3.6um, with 84%, 28%, and 24% also detected at 4.5, 5.8, and 8.0um, respectively. Number counts are consistent with results from other Spitzer surveys. Color distributions show that the EGS IRAC sources comprise a mixture of populations: low-redshift star-forming galaxies, quiescent galaxies dominated by stellar emission at a range of redshifts, and high-redshift galaxies and AGNs.
3974. Mid-IR Tully-Fisher relation with WISE & 2MTF
ID:
ivo://CDS.VizieR/J/ApJ/771/88
Title:
Mid-IR Tully-Fisher relation with WISE & 2MTF
Short Name:
J/ApJ/771/88
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a mid-infrared Tully-Fisher (TF) relation using photometry from the 3.4{mu}m W1 band of the Wide-field Infrared Survey Explorer (WISE) satellite. The WISE TF relation is formed from 568 galaxies taken from the all-sky 2MASS Tully-Fisher (2MTF) galaxy catalog, spanning a range of environments including field, group, and cluster galaxies. This constitutes the largest mid-infrared TF relation constructed to date. After applying a number of corrections to galaxy magnitudes and line widths, we measure a master TF relation given by M_corr_=-22.24-10.05[log(W_corr_)-2.5], with an average dispersion of {sigma}_WISE_=0.686mag. There is some tension between WISE TF and a preliminary 3.6{mu}m relation, which has a shallower slope and almost no intrinsic dispersion. However, our results agree well with a more recent relation constructed from a large sample of cluster galaxies. We additionally compare WISE TF to the near-infrared 2MTF template relations, finding a good agreement between the TF parameters and total dispersions of WISE TF and the 2MTF K-band template. This fact, coupled with typical galaxy colors of (K-W1)~0, suggests that these two bands are tracing similar stellar populations, including the older, centrally-located stars in the galactic bulge which can (for galaxies with a prominent bulge) dominate the light profile.
3975. Mid-IR variability from the SDWFS
ID:
ivo://CDS.VizieR/J/ApJ/716/530
Title:
Mid-IR variability from the SDWFS
Short Name:
J/ApJ/716/530
Date:
21 Oct 2021
Publisher:
CDS
Description:
We use the multi-epoch, mid-infrared Spitzer Deep Wide-Field Survey (SDWFS; Ashby et al. 2009, Cat. J/ApJ/701/428) to investigate the variability of objects in 8.1deg^2^ of the NOAO Deep Wide Field Survey Bootes field (NDWFS; Jannuzi & Dey 1999ASPC..191..111J). We perform a Difference Image Analysis of the four available epochs between 2004 and 2008, focusing on the deeper 3.6 and 4.5um bands. Out of 474, 179 analyzed sources, 1.1% meet our standard variability selection criteria that the two light curves are strongly correlated (r>0.8) and that their joint variance ({sigma}_12_) exceeds that for all sources with the same magnitude by 2{sigma}. We then examine the mid-IR colors of the variable sources and match them with X-ray sources from the XBootes survey (Murray et al. 2005ApJS..161....1M), radio catalogs (FIRST (Becker et al., Cat. VIII/71) and WSRT (de Vries et al. 2002, Cat. J/AJ/123/1784)), 24um selected active galactic nucleus (AGN) candidates (see Houck et al. 2005ApJ...622L.105H), and spectroscopically identified AGNs from the AGN and Galaxy Evolution Survey (AGES; C. S. Kochanek et al. 2010, in prep). Based on their mid-IR colors, most of the variable sources are AGNs (76%), with smaller contributions from stars (11%), galaxies (6%), and unclassified objects, although most of the stellar, galaxy, and unclassified sources are false positives. For our standard selection criteria, 11%-12% of the mid-IR counterparts to X-ray sources, 24um AGN candidates, and spectroscopically identified AGNs show variability.
3976. MIKE obs. of 2 metal-poor stars in Sylgr stream
ID:
ivo://CDS.VizieR/J/ApJ/883/84
Title:
MIKE obs. of 2 metal-poor stars in Sylgr stream
Short Name:
J/ApJ/883/84
Date:
21 Oct 2021
Publisher:
CDS
Description:
We observe two metal-poor main-sequence stars that are members of the recently discovered Sylgr stellar stream. We present radial velocities, stellar parameters, and abundances for 13 elements derived from high-resolution optical spectra collected using the Magellan Inamori Kyocera Echelle spectrograph. The two stars have identical compositions (within 0.13 dex or 1.2{sigma}) among all elements detected. Both stars are very metal-poor ([Fe/H]=-2.92+/-0.06). Neither star is highly enhanced in C ([C/Fe]<+1.0). Both stars are enhanced in the {alpha} elements Mg, Si, and Ca ([{alpha}/Fe]=+0.32+/-0.06), and the ratios among Na, Al, and all Fe-group elements are typical for other stars in the halo and ultra-faint and dwarf spheroidal galaxies at this metallicity. Sr is mildly enhanced ([Sr/Fe]=+0.22+/-0.11), but Ba is not enhanced ([Ba/Fe]{<}-0.4), indicating that these stars do not contain high levels of neutron-capture elements. The Li abundances match those found in metal-poor unevolved field stars and globular clusters (GCs) (log{epsilon}(Li)=2.05+/-0.07), which implies that environment is not a dominant factor in determining the Li content of metal-poor stars. The chemical compositions of these two stars cannot distinguish whether the progenitor of the Sylgr stream was a dwarf galaxy or a GC. If the progenitor was a dwarf galaxy, the stream may originate from a dense region such as a nuclear star cluster. If the progenitor was a GC, it would be the most metal-poor GC known.
3977. Milky way and stellar distributions
ID:
ivo://CDS.VizieR/J/AJ/118/895
Title:
Milky way and stellar distributions
Short Name:
J/AJ/118/895
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results of a photometric and spectroscopic study of stars in four fields toward the inner disk and Galactic bulge. The fields are located symmetrically about the minor axis of the Milky Way at (l, b)=(-24.8{deg}, -6.0{deg}), (-8.7{deg}, -6.0{deg}), (+8.4{deg}, -6.0{deg}), and (+24.4{deg}, -6.1{deg}). We measured radial velocities and strengths of selected absorption-line indexes and derived the average reddening to each field, individual metallicities and photometric parallaxes for each star, and mean azimuthal rotation velocities and velocity dispersions for each field.
3978. Milky Way classical Cepheids sample
ID:
ivo://CDS.VizieR/J/other/Sci/365.478
Title:
Milky Way classical Cepheids sample
Short Name:
J/other/Sci/365.
Date:
02 Nov 2021 11:28:21
Publisher:
CDS
Description:
The Milky Way is a barred spiral galaxy, with physical properties inferred from various tracers informed by the extrapolation of structures seen in other galaxies. However, the distances of these tracers are measured indirectly and are model-dependent. We constructed a map of the Milky Way in three dimensions, based on the positions and distances of thousands of classical Cepheid variable stars. This map shows the structure of our Galaxy's young stellar population and allows us to constrain the warped shape of the Milky Way's disk. A simple model of star formation in the spiral arms reproduces the observed distribution of Cepheids.
3979. Milky Way global survey of star clusters. V.
ID:
ivo://CDS.VizieR/J/A+A/585/A101
Title:
Milky Way global survey of star clusters. V.
Short Name:
J/A+A/585/A101
Date:
21 Oct 2021
Publisher:
CDS
Description:
We determined the integrated magnitudes of 3208 star clusters in the 2MASS near-infrared (JHKs) passbands.
3980. Milky Way halo velocity dispersion profile
ID:
ivo://CDS.VizieR/J/AJ/139/59
Title:
Milky Way halo velocity dispersion profile
Short Name:
J/AJ/139/59
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a spectroscopic sample of 910 distant halo stars from the Hypervelocity Star survey from which we derive the velocity dispersion profile of the Milky Way halo. The sample is a mix of 74% evolved horizontal branch stars and 26% blue stragglers. We estimate distances to the stars using observed colors, metallicities, and stellar evolution tracks. Our sample contains twice as many objects with R>50kpc as previous surveys. We compute the velocity dispersion profile in two ways: with a parametric method based on a Milky Way potential model and with a non-parametric method based on the caustic technique originally developed to measure galaxy cluster mass profiles. The resulting velocity dispersion profiles are remarkably consistent with those found by two independent surveys based on other stellar populations: the Milky Way halo exhibits a mean decline in radial velocity dispersion of -0.38+/-0.12km/s/kpc over 15<R<75kpc. This measurement is a useful basis for calculating the total mass and mass distribution of the Milky Way halo.