- ID:
- ivo://CDS.VizieR/J/ApJ/713/330
- Title:
- Spitzer observations of major-merger galaxies
- Short Name:
- J/ApJ/713/330
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Spitzer observations for a sample of close major-merger galaxy pairs (KPAIR sample) selected from cross-matches between the 2MASS Extended Source Catalog and Sloan Digital Sky Survey Data Release 3. The goals are to study the star formation activity in these galaxies and to set a local bench mark for the cosmic evolution of close major mergers. The Spitzer KPAIR sample (27 pairs, 54 galaxies) includes all spectroscopically confirmed spiral-spiral (S+S) and spiral-elliptical (S+E) pairs in a parent sample that is complete for primaries brighter than K=12.5 mag, projected separations of 5h^-1^kpc<=s<=20h^-1^kpc, and mass ratios <=2.5. The Spitzer data, consisting of images in seven bands (3.6, 4.5, 5.8, 8, 24, 70, 160um), show very diversified IR emission properties.
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Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/133/2072
- Title:
- Spitzer observations of NGC 2362
- Short Name:
- J/AJ/133/2072
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from a mid-infrared imaging survey of the ~5Myr old cluster NGC 2362 carried out with the Infrared Array Camera (IRAC) on board the Spitzer Space Telescope. The archival mid-infrared data were merged with extant Halpha emission data, optical and near-infrared photometry, and moderate-resolution optical spectroscopy to identify the remnant disk-bearing population of the cluster and to estimate the fraction of stars that still retain primordial circumstellar disks. The principal sample of 232 suspected cluster members with masses ranging from ~10 to 0.3M_{sun}_ (B2-M5 spectral types) was drawn from known Halpha emission stars, X-ray-detected stars from a single 100ks archival Chandra observation, and established lithium-rich stars. A second sample of 153 stars over a similar mass range whose membership status was based on optical photometry alone was also examined.
- ID:
- ivo://CDS.VizieR/J/ApJ/674/336
- Title:
- Spitzer observations of NGC 1333
- Short Name:
- J/ApJ/674/336
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a comprehensive analysis of structure in the young, embedded cluster, NGC 1333 using members identified with Spitzer and 2MASS photometry based on their IR-excess emission. A total of 137 members are identified in this way, composed of 39 protostars and 98 more evolved pre-main-sequence stars with disks. Of the latter class, four are transition/debris disk candidates.
- ID:
- ivo://CDS.VizieR/J/ApJ/698/1
- Title:
- Spitzer observations of NGC 2362
- Short Name:
- J/ApJ/698/1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Expanding upon the Infrared Array Camera (IRAC) survey from Dahm & Hillenbrand (2007, Cat. J/AJ/133/2072), we describe Spitzer IRAC and Multiband Imaging Photometer for Spitzer observations of the populous, 5Myr old open cluster NGC 2362. We analyze the mid-IR colors of cluster members and compared their spectral energy distributions (SEDs) to star+circumstellar disk models to constrain the disk morphologies and evolutionary states. Combining our data with other Spitzer surveys, we investigate the evolution of debris disks around high/intermediate-mass stars and investigate timescales for giant planet formation.
- ID:
- ivo://CDS.VizieR/J/AJ/141/11
- Title:
- Spitzer observations of planet-host stars
- Short Name:
- J/AJ/141/11
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Since giant planets scatter planetesimals within a few tidal radii of their orbits, the locations of existing planetesimal belts indicate regions where giant planet formation failed in bygone protostellar disks. Infrared observations of circumstellar dust produced by colliding planetesimals are therefore powerful probes of the formation histories of known planets. Here we present new Spitzer infrared spectrograph (IRS) spectrophotometry of 111 solar-type stars, including 105 planet hosts. Our observations reveal 11 debris disks, including two previously undetected debris disks orbiting HD 108874 and HD 130322. Combining the 32um spectrophotometry with previously published MIPS photometry, we find that the majority of debris disks around solar-type stars have temperatures in the range 60<~T_dust_<~100K. Assuming a dust temperature T_dust_=70K, which is representative of the nine debris disks detected by both IRS and MIPS, debris rings surrounding Sun-like stars orbit between 15 and 240AU depending on the mean particle size. Our observations imply that the planets detected by radial-velocity searches formed within 240AU of their parent stars. If any of the debris disks studied here have mostly large, blackbody emitting grains, their companion giant planets must have formed in a narrow region between the ice line and 15AU.
- ID:
- ivo://CDS.VizieR/J/ApJ/662/1067
- Title:
- Spitzer observations of sigma Orionis
- Short Name:
- J/ApJ/662/1067
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report new Spitzer Space Telescope observations, using the IRAC and MIPS instruments, of the young (~3Myr) sigma Orionis cluster. We identify 336 stars as members of the cluster, using optical and near-infrared color-magnitude diagrams. Using the spectral energy distribution slopes in the IRAC spectral range, we place objects into several classes: non-excess stars, stars with optically thick disks (such as classical T Tauri stars), class I (protostellar) candidates, and stars with "evolved disks"; the last exhibit smaller IRAC excesses than optically thick disk systems. In general, this classification agrees with the location expected in IRAC-MIPS color-color diagrams for these objects.
- ID:
- ivo://CDS.VizieR/J/ApJ/682/445
- Title:
- Spitzer observations of S254-S258
- Short Name:
- J/ApJ/682/445
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Spitzer IRAC, NOAO 2.1m Flamingos, Keck NIRC, and FCRAO SEQUOIA observations of the massive star-forming complex S254-S258, covering an area of 25'x20'. Using a combination of the IRAC and NIR data, we identify and classify the young stellar objects (YSOs) in the complex. We detect 510 sources with near- or mid-IR excess, and we classify 87 Class I and 165 Class II sources. The YSOs are found in clusters surrounded by isolated YSOs in a low-density distributed population. The ratio of clustered to total YSOs is 0.8. We identify six new clusters in the complex. One of them, G192.63-00, is located around the ionizing star of the HII region S255. We hypothesize that the ionizing star of S255 was formed in this cluster. We also detect a southern component of the cluster in HII region S256. The cluster G192.54-0.15, located inside HII region S254 has a V_LSR_ of 17km/s with respect to the main cloud, and we conclude that it is located in the background of the complex. The structure of the molecular cloud is examined using ^12^CO, and ^13^CO, as well as a near-IR extinction map. The main body of the molecular cloud has V_LSR_ between 5 and 9km/s. The arc-shaped structure of the molecular cloud following the border of the HII regions and the high column density in the border of the HII regions support the idea that the material has been swept up by the expansion of the HII regions.
- ID:
- ivo://CDS.VizieR/J/ApJ/664/850
- Title:
- Spitzer observations of stars in M33
- Short Name:
- J/ApJ/664/850
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyze five epochs of Spitzer Space Telescope Infrared Array Camera (IRAC) observations of the nearby spiral galaxy M33. Each epoch covered nearly a square degree at 3.6, 4.5, and 8.0um. The point-source catalog from the full data set contains 37650 stars. The stars have luminosities characteristic of the asymptotic giant branch and can be separated into oxygen-rich and carbon-rich populations by their [3.6]-[4.5] colors. The [3.6]-[8.0] colors indicate that over 80% of the stars detected at 8.0um have dust shells. Photometric comparison of epochs using conservative criteria yields a catalog of 2923 variable stars. These variables are most likely long-period variables amid an evolved stellar population. At least one-third of the identified carbon stars are variable.
- ID:
- ivo://CDS.VizieR/J/ApJS/186/111
- Title:
- Spitzer observations of Taurus members
- Short Name:
- J/ApJS/186/111
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have analyzed nearly all images of the Taurus star-forming region at 3.6, 4.5, 5.8, 8.0, and 24{mu}m that were obtained during the cryogenic mission of the Spitzer Space Telescope (46deg^2^) and have measured photometry for all known members of the region that are within these data, corresponding to 348 sources, or 99% of the known stellar population. By combining these measurements with previous observations with the Spitzer Infrared Spectrograph and other facilities, we have classified the members of Taurus according to whether they show evidence of circumstellar disks and envelopes (classes I, II, and III). Through these classifications, we find that the disk fraction in Taurus, N(II)/N(II+III), is ~75% for solar-mass stars and declines to ~45% for low-mass stars and brown dwarfs (0.01-0.3M_{sun}_). Through an analysis of multiple epochs of Spitzer photometry that are available for ~200 Taurus members, we find that stars with disks exhibit significantly greater mid-infrared (mid-IR) variability than diskless stars, which agrees with the results of similar variability measurements for a smaller sample of stars in Chamaeleon I. The variability fraction for stars with disks is higher in Taurus than in Chamaeleon I, indicating that the IR variability of disks decreases with age. Finally, we have used our data in Taurus to refine the observational criteria for primordial, evolved, and transitional disks. The ratio of the number of evolved and transitional disks to the number of primordial disks in Taurus is 15/98 for spectral types of K5-M5, indicating a timescale of 0.15x{tau}_primordial_~0.45Myr for the clearing of the inner regions of optically thick disks.
- ID:
- ivo://CDS.VizieR/J/A+A/471/L51
- Title:
- Spitzer observations of the hot Neptune GJ 436b
- Short Name:
- J/A+A/471/L51
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Spitzer Space Telescope infrared photometry of a primary transit of the hot Neptune GJ 436b. The observations were obtained using the 8{mu}m band of the InfraRed Array Camera (IRAC).