- ID:
- ivo://CDS.VizieR/J/ApJ/671/323
- Title:
- Spitzer Spectra of a 10mJy galaxy sample
- Short Name:
- J/ApJ/671/323
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A complete flux-limited sample of 50 galaxies is presented having f{nu}(24um)>10mJy, chosen from a survey with MIPS on Spitzer of 8.2deg^2^ in the NOAO Deep Wide-Field Survey (NDWFS) region in Bootes. Spectra obtained with the low-resolution modules of IRS on Spitzer are described for 36 galaxies in this sample; 25 show strong PAH emission features characteristic of starbursts, and 11 show silicate absorption or emission, emission lines, or featureless spectra characteristic of AGNs. Infrared or optical spectral classifications are available for 48 of the entire sample of 50; 33 galaxies are classified as starbursts and 15 as AGNs.
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Search Results
- 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.
17683. Spitzer survey of NGC 2451
- 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/ApJ/663/1149
- Title:
- Spitzer survey of Serpens YSO population
- Short Name:
- J/ApJ/663/1149
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We discuss the combined IRAC/MIPS c2d Spitzer Legacy observations of the Serpens star-forming region. We describe criteria for isolating bona fide YSOs from the extensive background of extragalactic objects. We then discuss the properties of the resulting high-confidence set of 235 YSOs. An additional 51 lower confidence YSOs outside this area are identified from the MIPS data and 2MASS photometry. We present color-color diagrams to compare our observed source properties with those of theoretical models for star/disk/envelope systems and our own modeling of the objects that are well represented by a stellar photosphere plus circumstellar disk.
- ID:
- ivo://CDS.VizieR/J/PASP/122/1397
- Title:
- Spitzer Survey of Stellar Structure in Galaxies
- Short Name:
- J/PASP/122/1397
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Spitzer Survey of Stellar Structure in Galaxies (S^4^G) is an Exploration Science Legacy Program approved for the Spitzer post-cryogenic mission. It is a volume-, magnitude-, and size-limited (d<40Mpc, |b|>30{deg}, m_Bcorr_<15.5, and D_25_>1') survey of 2331 galaxies using the Infrared Array Camera (IRAC) at 3.6 and 4.5um. Each galaxy is observed for 240s and mapped to >=1.5D_25_. The final mosaicked images have a typical 1sigma rms noise level of 0.0072 and 0.0093MJy/sr at 3.6 and 4.5um, respectively. Our azimuthally averaged surface brightness profile typically traces isophotes at {mu}_3.6um_(AB)(1sigma)~27mag/arcsec^2^, equivalent to a stellar mass surface density of ~1M_{sun}_/pc^2^. thus provides an unprecedented data set for the study of the distribution of mass and stellar structures in the local universe. This large, unbiased, and extremely deep sample of all Hubble types from dwarfs to spirals to ellipticals will allow for detailed structural studies, not only as a function of stellar mass, but also as a function of the local environment. This article introduces the survey and describes the sample selection, the significance of the 3.6 and 4.5um bands for this study, and the data collection and survey strategies.
- ID:
- ivo://CDS.VizieR/J/ApJ/699/1610
- Title:
- Spitzer survey of submillimeter galaxies
- Short Name:
- J/ApJ/699/1610
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Spitzer-IRAC and MIPS mid-IR observations of a sample of 76 radio-detected submillimeter-selected galaxies (SMGs) with spectroscopic redshifts, the largest such sample published to date. From our data, we find that IRAC colors of SMGs are much more uniform as compared with rest-frame UV and optical colors, and z>1.5 SMGs tend to be redder in their mid-IR colors than both field galaxies and lower-z SMGs. However, the IRAC colors of the SMGs overlap those of field galaxies sufficiently that color-magnitude and color-color selection criteria suggested in the literature to identify SMG counterparts produce ambiguous counterparts within an 8" radius in 20%-35% of cases. We use a rest-frame J-H versus H-K color-color diagram and a S24/S8.0 versus S8.0/S4.5 color-color diagram to determine that 13%-19% of our sample are likely to contain active galactic nuclei which dominate their mid-IR emission.
- 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.