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14391. Spitzer-FLS catalog of clusters of galaxies
ID:
ivo://CDS.VizieR/J/ApJ/686/966
Title:
Spitzer-FLS catalog of clusters of galaxies
Short Name:
J/ApJ/686/966
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a catalog of 99 candidate clusters and groups of galaxies in the redshift range 0.1<z_phot_<1.3 discovered in the Spitzer First-Look Survey (FLS). The clusters are selected by their Rc-3.6um galaxy color-magnitude relation using the cluster red-sequence algorithm. Using this cluster sample, we compute the 3.6, 4.5, 5.8, and 8.0um, cluster luminosity functions (LFs).
14392. Spitzer follow up of 95 brown dwarfs
ID:
ivo://CDS.VizieR/J/ApJ/899/123
Title:
Spitzer follow up of 95 brown dwarfs
Short Name:
J/ApJ/899/123
Date:
14 Mar 2022 07:05:10
Publisher:
CDS
Description:
We present Spitzer follow-up imaging of 95 candidate extremely cold brown dwarfs discovered by the Backyard Worlds: Planet 9 citizen science project, which uses visually perceived motion in multiepoch Wide-field Infrared Survey Explorer (WISE) images to identify previously unrecognized substellar neighbors to the Sun. We measure Spitzer [3.6]-[4.5] color to phototype our brown dwarf candidates, with an emphasis on pinpointing the coldest and closest Y dwarfs within our sample. The combination of WISE and Spitzer astrometry provides quantitative confirmation of the transverse motion of 75 of our discoveries. Nine of our motion-confirmed objects have best-fit linear motions larger than 1"/yr; our fastest-moving discovery is WISEAJ155349.96+693355.2 ({mu}~2.15/yr), a possible T-type subdwarf. We also report a newly discovered wide-separation (~400au) T8 comoving companion to the white dwarf LSPMJ0055+5948 (the fourth such system to be found), plus a candidate late T companion to the white dwarf LSRJ0002+6357 at 5.5 projected separation (~8700au if associated). Among our motion-confirmed targets, five have Spitzer colors most consistent with spectral type Y. Four of these five have exceptionally red Spitzer colors suggesting types of Y1 or later, adding considerably to the small sample of known objects in this especially valuable low-temperature regime. Our Y dwarf candidates begin bridging the gap between the bulk of the Y dwarf population and the coldest known brown dwarf.
14393. Spitzer h and {chi} Persei candidate members
ID:
ivo://CDS.VizieR/J/ApJ/796/127
Title:
Spitzer h and {chi} Persei candidate members
Short Name:
J/ApJ/796/127
Date:
21 Oct 2021
Publisher:
CDS
Description:
We analyze very deep Infrared Array Camera and Multiband Imaging Photometer for Spitzer (MIPS) photometry of ~12500 members of the 14 Myr old Double Cluster, h and {chi} Persei, building upon our earlier, shallower Spitzer Cycle 1 studies. Numerous likely members show infrared (IR) excesses at 8 {mu}m and 24 {mu}m, indicative of circumstellar dust. The frequency of stars with 8 {mu}m excess is at least 2% for our entire sample, slightly lower (higher) for B/A stars (later type, lower mass stars). Optical spectroscopy also identifies gas in about 2% of systems, but with no clear trend between the presence of dust and gas. Spectral energy distribution modeling of 18 sources with detections at optical wavelengths through MIPS 24 {mu}m reveals a diverse set of disk evolutionary states, including a high fraction of transitional disks, though similar data for all disk-bearing members would provide constraints. Using Monte Carlo simulations, we combine our results with those for other young clusters to study the global evolution of dust/gas disks. For nominal cluster ages, the e-folding times ({tau}_0_) for the frequency of warm dust and gas are 2.75 Myr and 1.75 Myr, respectively. Assuming a revised set of ages for some clusters, these timescales increase to 5.75 and 3.75 Myr, respectively, implying a significantly longer typical protoplanetary disk lifetime than previously thought. In both cases, the transitional disk duration, averaged over multiple evolutionary pathways, is ~1 Myr. Finally, 24 {mu}m excess frequencies for 4-6 M_{sun}_ stars appear lower than for 1-2.5 M_{sun}_ stars in other 10-30 Myr old clusters.
14394. Spitzer high-resolution MIR spectral atlas
ID:
ivo://CDS.VizieR/J/ApJS/184/230
Title:
Spitzer high-resolution MIR spectral atlas
Short Name:
J/ApJS/184/230
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present an atlas of Spitzer/IRS high-resolution (R~600) 10-37um spectra for 24 well known starburst galaxies. The spectra are dominated by fine-structure lines, molecular hydrogen lines, and emission bands of polycyclic aromatic hydrocarbons (PAHs). Six out of the eight objects with a known active galactic nucleus (AGN) component show emission of the high excitation [NeV] line. This line is also seen in one other object (NGC 4194) with, a priori, no known AGN component. In addition to strong PAH emission features in this wavelength range (11.3, 12.7, 16.4um), the spectra reveal other weak hydrocarbon features at 10.6, 13.5, 14.2um, and a previously unreported emission feature at 10.75um. An unidentified absorption feature at 13.7um is detected in many of the starbursts. We use the fine-structure lines to derive the abundance of neon and sulfur for 14 objects where the HI 7-6 line is detected. We further use the molecular hydrogen lines to sample the properties of the warm molecular gas. Several basic diagrams characterizing the properties of the sample are also shown. We have combined the spectra of all the pure starburst objects to create a high signal-to-noise ratio template, which is available to the community.
14395. Spitzer imaging of Cepheus OB3b cluster
ID:
ivo://CDS.VizieR/J/ApJ/750/125
Title:
Spitzer imaging of Cepheus OB3b cluster
Short Name:
J/ApJ/750/125
Date:
21 Oct 2021
Publisher:
CDS
Description:
We map the full extent of a rich massive young cluster in the Cep OB3b association with the Infrared Array Camera and Multi-band Imaging Photometer System instruments aboard the Spitzer Space Telescope and the ACIS instrument aboard the Chandra X-Ray Observatory. At 700 pc, it is revealed to be the second nearest large (>1000 member), young (<5 Myr) cluster known. In contrast to the nearest large cluster, the Orion Nebula Cluster, Cep OB3b is only lightly obscured and is mostly located in a large cavity carved out of the surrounding molecular cloud. Our infrared and X-ray data sets, as well as visible photometry from the literature, are used to take a census of the young stars in Cep OB3b. We find that the young stars within the cluster are concentrated in two sub-clusters; an eastern sub-cluster, near the Cep B molecular clump, and a western sub-cluster, near the Cep F molecular clump. Using our census of young stars, we examine the fraction of young stars with infrared excesses indicative of circumstellar disks. We create a map of the disk fraction throughout the cluster and find that it is spatially variable. Due to these spatial variations, the two sub-clusters exhibit substantially different average disk fractions from each other: 32%+/-4% and 50%+/-6%. We discuss whether the discrepant disk fractions are due to the photodestruction of disks by the high mass members of the cluster or whether they result from differences in the ages of the sub-clusters. We conclude that the discrepant disk fractions are most likely due to differences in the ages.
14396. Spitzer interstellar bubbles
ID:
ivo://CDS.VizieR/J/MNRAS/438/426
Title:
Spitzer interstellar bubbles
Short Name:
J/MNRAS/438/426
Date:
21 Oct 2021
Publisher:
CDS
Description:
The expansion of interstellar bubbles is suggested to be an important mechanism of triggering material accumulation and star formation. In this work, we investigate the gaseous environment of a large sample of interstellar bubbles identified by the Spitzer space telescope, aiming to explore the possible evidence of triggered gas accumulation and star formation in a statistical sense. By cross-matching 6124 Spitzer interstellar bubbles from the Milky Way Project (MWP) and more than 2500 Galactic HII regions collected by us, we obtain the velocity information for 818 MWP bubbles. To study the gaseous environment of the interstellar bubbles and get rid of the projection effect as much as possible, we constrain the velocity difference between the bubbles and the ^13^CO(1-0) emission extracted from the Galactic Ring Survey (GRS). Three methods: the mean azimuthally averaged radial profile of ^13^CO emission, the surface number density of molecular clumps and the angular cross-correlation function of MWP bubbles and the GRS molecular clumps are adopted. Significant over density of molecular gas is found to be close to the bubble rims. 60 percent of the studied bubbles were found to have associated molecular clumps. By comparing the clump-associated and the clump-unassociated MWP interstellar bubbles, we reveal that the bubbles in associations tend to be larger and thicker in physical sizes. From the different properties shown by the bubble-associated and bubble-unassociated clumps, we speculate that some of the bubble-associated clumps result from the expansion of bubbles. The fraction of the molecular clumps associated with the MWP bubbles is estimated to be about 20 percent after considering the projection effect. For the bubble-clump complexes, we found that the bubbles in the complexes with associated massive young stellar object(s) (MYSO(s)) have larger physical sizes, hence the complexes tend to be older. We propose that an evolutionary sequence might exist between the relatively younger MYSO-unassociated bubble-clump complexes and the MYSO-associated complexes.
14397. Spitzer IRAC events observed in crowded fields
ID:
ivo://CDS.VizieR/J/ApJ/814/92
Title:
Spitzer IRAC events observed in crowded fields
Short Name:
J/ApJ/814/92
Date:
21 Oct 2021
Publisher:
CDS
Description:
We develop a new photometry algorithm that is optimized for the Infrared Array Camera (IRAC) Spitzer time series in crowded fields and that is particularly adapted to faint or heavily blended targets. We apply this to the 170 targets from the 2015 Spitzer microlensing campaign and present the results of three variants of this algorithm in an online catalog. We present detailed accounts of the application of this algorithm to two difficult cases, one very faint and the other very crowded. Several of Spitzer's instrumental characteristics that drive the specific features of this algorithm are shared by Kepler and WFIRST, implying that these features may prove to be a useful starting point for algorithms designed for microlensing campaigns by these other missions.
14398. Spitzer/IRAC-MIPS survey of NGC 2244
ID:
ivo://CDS.VizieR/J/ApJ/660/1532
Title:
Spitzer/IRAC-MIPS survey of NGC 2244
Short Name:
J/ApJ/660/1532
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results from a survey of NGC 2244 from 3.6 to 24um with the Spitzer Space Telescope. The 24um-8um-3.6um color composite image of the region shows that the central cavity surrounding the multiple O and B stars of NGC 2244 contains a large amount of cool dust visible only at 24um. Our survey gives a detailed look at disk survivability within the hot-star-dominated environment in this cavity. Using mid-infrared two-color diagrams ([3.6]-[4.5] vs. [5.8]-[8.0]), we identified 337 class II and 25 class I objects out of 1084 objects detected in all four of these bands with photometric uncertainty better than 10%. Including the 24um data, we found 213 class II and 20 class I sources out of 279 stars also detected at this latter band. The center of the class II density contours is in very good agreement with the center of the cluster detected in the 2MASS images. We studied the distribution of the class II sources relative to the O stars and found that the effect of high-mass stars on the circumstellar disks is significant only in their immediate vicinity.
14399. Spitzer/IRAC observations of five deep fields
ID:
ivo://CDS.VizieR/J/ApJ/769/80
Title:
Spitzer/IRAC observations of five deep fields
Short Name:
J/ApJ/769/80
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Spitzer Extended Deep Survey (SEDS) is a very deep infrared survey within five well-known extragalactic science fields: the UKIDSS Ultra-Deep Survey, the Extended Chandra Deep Field South, COSMOS, the Hubble Deep Field North, and the Extended Groth Strip. SEDS covers a total area of 1.46deg^2^ to a depth of 26 AB mag (3{sigma}) in both of the warm Infrared Array Camera (IRAC) bands at 3.6 and 4.5{mu}m. Because of its uniform depth of coverage in so many widely-separated fields, SEDS is subject to roughly 25% smaller errors due to cosmic variance than a single-field survey of the same size. SEDS was designed to detect and characterize galaxies from intermediate to high redshifts (z=2-7) with a built-in means of assessing the impact of cosmic variance on the individual fields. Because the full SEDS depth was accumulated in at least three separate visits to each field, typically with six-month intervals between visits, SEDS also furnishes an opportunity to assess the infrared variability of faint objects. This paper describes the SEDS survey design, processing, and publicly-available data products. Deep IRAC counts for the more than 300000 galaxies detected by SEDS are consistent with models based on known galaxy populations. Discrete IRAC sources contribute 5.6+/-1.0 and 4.4+/-0.8nW/m2/sr at 3.6 and 4.5{mu}m to the diffuse cosmic infrared background (CIB). IRAC sources cannot contribute more than half of the total CIB flux estimated from DIRBE data. Barring an unexpected error in the DIRBE flux estimates, half the CIB flux must therefore come from a diffuse component.
14400. Spitzer/IRAC observations of SMC Cepheids
ID:
ivo://CDS.VizieR/J/ApJ/816/49
Title:
Spitzer/IRAC observations of SMC Cepheids
Short Name:
J/ApJ/816/49
Date:
21 Oct 2021
Publisher:
CDS
Description:
Using Spitzer observations of classical Cepheids we have measured the true average distance modulus of the Small Magellanic Cloud (SMC) to be 18.96+/-0.01_stat_+/-0.03_sys_mag (corresponding to 62+/-0.3kpc), which is 0.48+/-0.01mag more distant than the LMC. This is in agreement with previous results from Cepheid observations, as well as with measurements from other indicators such as RR Lyrae stars and the tip of the red giant branch. Utilizing the properties of the mid-infrared Leavitt Law we measured precise distances to individual Cepheids in the SMC, and have confirmed that the galaxy is tilted and elongated such that its eastern side is up to 20kpc closer than its western side. This is in agreement with the results from red clump stars and dynamical simulations of the Magellanic Clouds and Stream.

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