- ID:
- ivo://CDS.VizieR/J/ApJ/697/1993
- Title:
- Spitzer study of AGB stars. III.
- Short Name:
- J/ApJ/697/1993
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the third and final part of a census of asymptotic giant branch (AGB) stars in Local Group dwarf irregular (dIrr) galaxies. Papers I (Jackson et al. 2007ApJ...656..818J) and II (Jackson et al. 2007ApJ...667..891J) presented the results for WLM and IC 1613. Included here are Phoenix, LGS 3, DDO 210, Leo A, Pegasus dIrr, and Sextans A. Spitzer photometry at 3.6, 4.5, 5.8, and 8um are presented, along with a more thorough treatment of background galaxy contamination than was presented in Papers I and II. We find that at least a small population of completely optically obscured AGB stars exists in each galaxy, regardless of the galaxy's metallicity, but that higher metallicity galaxies tend to harbor more stars with slight infrared excesses.
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- ID:
- ivo://CDS.VizieR/J/ApJ/698/1989
- Title:
- Spitzer survey of NGC 2451
- Short Name:
- J/ApJ/698/1989
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a Spitzer IRAC and MIPS survey of NGC 2451A and B, two open clusters in the 50-80Myr age range. We complement these data with extensive ground-based photometry and spectroscopy to identify the cluster members in the Spitzer survey field. We find only two members with 8um excesses. The incidence of excesses at 24um is much higher, i.e., 11 of 31 solar-like stars and 1 of 7 early-type (A) stars. This work nearly completes the debris disk surveys with Spitzer of clusters in the 30-130Myr range. This range is of interest because it is when large planetesimal collisions may have still been relatively common (as indicated by the one that led to the formation of the Moon during this period of the evolution of the solar system). We review the full set of surveys and find that there are only three possible cases out of about 250 roughly solar-mass stars where very large excesses suggest that such collisions have occurred recently.
- ID:
- ivo://CDS.VizieR/J/AJ/144/192
- Title:
- Spitzer survey of Orion A and B. I. YSO catalog
- Short Name:
- J/AJ/144/192
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a survey of the Orion A and B molecular clouds undertaken with the IRAC and MIPS instruments on board Spitzer. In total, five distinct fields were mapped, covering 9deg^2^ in five mid-IR bands spanning 3-24{mu}m. The survey includes the Orion Nebula Cluster, the Lynds 1641, 1630, and 1622 dark clouds, and the NGC 2023, 2024, 2068, and 2071 nebulae. These data are merged with the Two Micron All Sky Survey point source catalog to generate a catalog of eight-band photometry. We identify 3479 dusty young stellar objects (YSOs) in the Orion molecular clouds by searching for point sources with mid-IR colors indicative of reprocessed light from dusty disks or infalling envelopes. The YSOs are subsequently classified on the basis of their mid-IR colors and their spatial distributions are presented. We classify 2991 of the YSOs as pre-main-sequence stars with disks and 488 as likely protostars. Most of the sources were observed with IRAC in two to three epochs over six months; we search for variability between the epochs by looking for correlated variability in the 3.6 and 4.5{mu}m bands. We find that 50% of the dusty YSOs show variability. The variations are typically small (~0.2mag) with the protostars showing a higher incidence of variability and larger variations. The observed correlations between the 3.6, 4.5, 5.8, and 8{mu}m variability suggests that we are observing variations in the heating of the inner disk due to changes in the accretion luminosity or rotating accretion hot spots.
- ID:
- ivo://CDS.VizieR/J/ApJS/237/39
- Title:
- Spitzer survey of UltraVISTA deep Stripes (SMUVS)
- Short Name:
- J/ApJS/237/39
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper describes new deep 3.6 and 4.5{mu}m imaging of three UltraVISTA near-infrared survey stripes within the COSMOS field. The observations were carried out with Spitzer's Infrared Array Camera (IRAC) for the Spitzer Matching Survey of the UltraVISTA Deep Stripes (SMUVS). In this work we present our data reduction techniques, and document the resulting mosaics, coverage maps, and catalogs in both IRAC passbands for the three easternmost UltraVISTA survey stripes, covering a combined area of about 0.66deg^2^, of which 0.45deg^2^ have at least 20hr of integration time. SMUVS reaches point-source sensitivities of about 25.0 AB mag (0.13{mu}Jy) at both 3.6 and 4.5{mu}m, with a significance of 4{sigma}, accounting for both survey sensitivity and source confusion. To this limit the SMUVS catalogs contain a total of ~350,000 sources, each of which is detected significantly in at least one IRAC band. Because of its uniform and high sensitivity, relatively large area coverage, and the wide array of ancillary data available in COSMOS, the SMUVS survey will be useful for a large number of cosmological investigations.
- ID:
- ivo://CDS.VizieR/J/ApJS/184/18
- Title:
- Spitzer survey of young stellar clusters
- Short Name:
- J/ApJS/184/18
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a uniform mid-infrared imaging and photometric survey of 36 young, nearby, star-forming clusters and groups using Spitzer IRAC and MIPS. We have confidently identified and classified 2548 young stellar objects (YSOs) using recently established mid-infrared color-based methods. We have devised and applied a new algorithm for the isolation of local surface density enhancements from point source distributions, enabling us to extract the overdense cores of the observed star-forming regions for further analysis. We have compiled several basic structural measurements of these cluster cores from the data, such as mean surface densities of sources, cluster core radii, and aspect ratios, in order to characterize the ranges for these quantities. We find that a typical cluster core is 0.39pc in radius, has 26 members with infrared excess in a ratio of Class II to Class I sources of 3.7, is embedded in a A_Ks_=0.8mag cloud clump, and has a surface density of 60pc^-2^. We examine the nearest neighbor distances among the YSOs in several ways, demonstrating similarity in the spacings between Class II and Class I sources but large member clusters appear more dense than smaller clusters. We demonstrate that near-uniform source spacings in cluster cores are common, suggesting that simple Jeans fragmentation of parsec-scale cloud clumps may be the dominant process governing star formation in nearby clusters and groups. Finally, we compare our results to other similar surveys in the literature and discuss potential biases in the data to guide further interpretation.
- ID:
- ivo://CDS.VizieR/J/AJ/160/38
- Title:
- Spitzer variability detections of 79 brown dwarfs
- Short Name:
- J/AJ/160/38
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Spitzer Space Telescope variability monitoring observations of three low-gravity L dwarfs with previous detections of variability in the near-IR: 2MASSJ0045+16, 2MASSJ0501-00, and 2MASSJ1425-36. We detect significant periodic variability in two of our targets, 2MASS J0045+16 and 2MASS J0501-00. We do not detect variability in 2MASS J1425-36. Combining our new rotation periods with rotational velocities, we calculate inclination angles of 22{deg}{+/-}1{deg}, 60_-8_^+13^{deg}, and 52_-13_^+19^{deg} for 2MASSJ0045+16, 2MASSJ0501-00, and 2MASSJ1425-36, respectively. Our three new objects are consistent with the tentative relations between inclination, amplitude, and color anomaly previously reported. Objects with the highest variability amplitudes are inclined equator on, while the maximum observed amplitude decreases as the inclination angle decreases. We also find a correlation between the inclination angle and (J-K)_2MASS_ color anomaly for the sample of objects with measured inclinations. Compiling the entire sample of brown dwarfs with Spitzer variability detections, we find no enhancement in amplitude for young, early-L dwarfs compared to the field dwarf population. We find a possible enhancement in amplitude of low-gravity late-L dwarfs at 4.5{mu}m. We do not find a correlation between amplitude ratio and spectral type for field dwarfs or for the young population. Finally, we compile the rotation periods of a large sample of brown dwarfs with ages 1Myr-1Gyr and compare the rotation rates predicted by evolutionary models assuming angular momentum conservation. We find that the rotation rates of the current sample of brown dwarfs fall within the expected range set by evolutionary models and breakup limits.
- ID:
- ivo://CDS.VizieR/J/ApJ/863/15
- Title:
- Spitzer, VLT and Keck NIR light curves of SgrA*
- Short Name:
- J/ApJ/863/15
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Sagittarius A* (Sgr A*) is the variable radio, near-infrared (NIR), and X-ray source associated with accretion onto the Galactic center black hole. We present an analysis of the most comprehensive NIR variability data set of Sgr A* to date: eight 24 hr epochs of continuous monitoring of Sgr A* at 4.5{mu}m with the IRAC instrument on the Spitzer Space Telescope, 93 epochs of 2.18{mu}m data from Naos Conica at the Very Large Telescope, and 30 epochs of 2.12{mu}m data from the NIRC2 camera at the Keck Observatory, in total 94929 measurements. A new approximate Bayesian computation method for fitting the first-order structure function extracts information beyond current fast Fourier transformation (FFT) methods of power spectral density (PSD) estimation. With a combined fit of the data of all three observatories, the characteristic coherence timescale of Sgr A* is {tau}_b_=243_-57_^+82^min (90% credible interval). The PSD has no detectable features on timescales down to 8.5min (95% credible level), which is the ISCO orbital frequency for a dimensionless spin parameter a=0.92. One light curve measured simultaneously at 2.12 and 4.5{mu}m during a low flux-density phase gave a spectral index {alpha}_s_=1.6+/-0.1 (F_{nu}_{propto}{nu}^-{alpha}_s_^). This value implies that the Sgr A* NIR color becomes bluer during higher flux-density phases. The probability densities of flux densities of the combined data sets are best fit by log-normal distributions. Based on these distributions, the Sgr A* spectral energy distribution is consistent with synchrotron radiation from a non-thermal electron population from below 20GHz through the NIR.
- ID:
- ivo://CDS.VizieR/J/ApJ/752/45
- Title:
- SPLASH: Stellar spectroscopy of M31 satellites
- Short Name:
- J/ApJ/752/45
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a resolved star spectroscopic survey of 15 dwarf spheroidal (dSph) satellites of the Andromeda galaxy (M31). We filter foreground contamination from Milky Way (MW) stars, noting that MW substructure is evident in this contaminant sample. We also filter M31 halo field giant stars and identify the remainder as probable dSph members. We then use these members to determine the kinematical properties of the dSphs. For the first time, we confirm that And XVIII, XXI, and XXII show kinematics consistent with bound, dark-matter-dominated galaxies. From the velocity dispersions for the full sample of dSphs we determine masses, which we combine with the size and luminosity of the galaxies to produce mass-size-luminosity scaling relations. With these scalings we determine that the M31 dSphs are fully consistent with the MW dSphs, suggesting that the well-studied MW satellite population provides a fair sample for broader conclusions. We also estimate dark matter halo masses of the satellites and find that there is no sign that the luminosity of these galaxies depends on their dark halo mass, a result consistent with what is seen for MW dwarfs. Two of the M31 dSphs (And XV, XVI) have estimated maximum circular velocities smaller than 12 km/s (to 1{sigma}), which likely places them within the lowest-mass dark matter halos known to host stars (along with Bootes I of the MW). Finally, we use the systemic velocities of the M31 satellites to estimate the mass of the M31 halo, obtaining a virial mass consistent with previous results.
- ID:
- ivo://CDS.VizieR/J/ApJS/235/36
- Title:
- SPLASH-SXDF multi-wavelength photometric catalog
- Short Name:
- J/ApJS/235/36
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a multi-wavelength catalog in the Subaru/XMM-Newton Deep Field (SXDF) as part of the Spitzer Large Area Survey with Hyper-Suprime-Cam (SPLASH). We include the newly acquired optical data from the Hyper-Suprime-Cam Subaru Strategic Program, accompanied by IRAC coverage from the SPLASH survey. All available optical and near-infrared data is homogenized and resampled on a common astrometric reference frame. Source detection is done using a multi-wavelength detection image including the u-band to recover the bluest objects. We measure multi-wavelength photometry and compute photometric redshifts as well as physical properties for ~1.17 million objects over ~4.2deg^2^, with ~800000 objects in the 2.4deg^2^ HSC-Ultra-Deep coverage. Using the available spectroscopic redshifts from various surveys over the range of 0<z<6, we verify the performance of the photometric redshifts and we find a normalized median absolute deviation of 0.023 and outlier fraction of 3.2%. The SPLASH-SXDF catalog is a valuable, publicly available resource, perfectly suited for studying galaxies in the early universe and tracing their evolution through cosmic time.
6290. SPM 4.0 Catalog
- ID:
- ivo://CDS.VizieR/I/320
- Title:
- SPM 4.0 Catalog
- Short Name:
- I/320
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The SPM4 Catalog contains absolute proper motions, celestial coordinates, and B,V photometry for 103,319,647 stars and galaxies between the south celestial pole and -20 degrees declination. The catalog is roughly complete to V=17.5. It is based on photographic and CCD observations taken with the Yale Southern Observatory's double-astrograph at Cesco Observatory in El Leoncito, Argentina. The first-epoch survey, taken from 1965 to 1979, was entirely photographic. The second-epoch survey is approximately 1/3 photographic (taken from 1988 to 1998) and 2/3 CCD-based (taken from 2004 through 2008). Full details about the creation of the SPM4.0 catalog can be found in the paper, and also in the document "spm4_doc.txt" file which describes the original files, accessible from http://www.astro.yale.edu/astrom/spm4cat/