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- ID:
- ivo://CDS.VizieR/J/A+A/423/849
- Title:
- Spiral galaxies observed in the K band
- Short Name:
- J/A+A/423/849
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A sample of 54 nearby spiral galaxies was observed in the K' band with 3.5m NTT telescope, La Silla, ESO, to study the morphology and other properties of spiral perturbations in their disks. A subsample of the galaxies classified as ordinary, non-barred spirals was used to estimate frequency of weak bars detectable in the K' band. The tables provide general structural properties of the galaxies including estimated of the bulge/disk decomposition and spiral perturbations in the disks.
- ID:
- ivo://CDS.VizieR/J/MNRAS/456/3335
- Title:
- SPIRE observations of Herschel-BAT sample
- Short Name:
- J/MNRAS/456/3335
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present far-infrared (FIR) and submillimetre photometry from the Herschel Space Observatory's Spectral and Photometric Imaging Receiver (SPIRE) for 313 nearby (z<0.05) active galactic nuclei (AGN). We selected AGN from the 58 month Swift Burst Alert Telescope (BAT) catalogue, the result of an all-sky survey in the 14-195keV energy band, allowing for a reduction in AGN selection effects due to obscuration and host galaxy contamination. We find 46 per cent (143/313) of our sample is detected at all three wavebands and combined with our Photoconductor Array Camera and Spectrometer (PACS) observations represents the most complete FIR spectral energy distributions of local, moderate-luminosity AGN. We find no correlation among the 250, 350, and 500{mu}m luminosities with 14-195keV luminosity, indicating the bulk of the FIR emission is not related to the AGN. However, Seyfert 1s do show a very weak correlation with X-ray luminosity compared to Seyfert 2s and we discuss possible explanations. We compare the SPIRE colours (F_250_/F_350_ and F_350_/F_500_) to a sample of normal star-forming galaxies, finding the two samples are statistically similar, especially after matching in stellar mass. But a colour-colour plot reveals a fraction of the Herschel-BAT AGN are displaced from the normal star-forming galaxies due to excess 500{mu}m emission (E_500_). Our analysis shows E_500_ is strongly correlated with the 14-195keV luminosity and 3.4/4.6{mu}m flux ratio, evidence the excess is related to the AGN. We speculate these sources are experiencing millimetre excess emission originating in the corona of the accretion disc.
- ID:
- ivo://CDS.VizieR/J/ApJ/685/958
- Title:
- Spitzer and Chandra sources in galactic center
- Short Name:
- J/ApJ/685/958
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have studied the correlation between 2357 Chandra X-ray point sources in a 40x40pc field and ~20000 infrared sources we observed in the corresponding subset of our 2x1.4{deg} Spitzer/IRAC Galactic Center Survey at 3.6-8.0um, using various spatial and X-ray hardness thresholds. The correlation was determined for source separations of less than 0.5", 1", or 2". Only the soft X-ray sources show any correlation with infrared point sources on these scales, and that correlation is very weak. The upper limit on hard X-ray sources that have infrared counterparts is <1.7% (3{sigma}). However, because of the confusion limit of the IR catalog, we only detect IR sources with absolute magnitudes <~1. As a result, a stronger correlation with fainter sources cannot be ruled out. Only one compact IR source, IRS 13, coincides with any of the dozen prominent X-ray emission features in the 3x3pc region centered on Sgr A*, and the diffuse X-ray and IR emission around Sgr A* seems to be anticorrelated on a few-arcsecond scale. We compare our results with previous identifications of near-infrared companions to Chandra X-ray sources.
- ID:
- ivo://CDS.VizieR/J/ApJ/768/25
- Title:
- Spitzer and Herschel observations of debris disks
- Short Name:
- J/ApJ/768/25
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We explore the collisional decay of disk mass and infrared emission in debris disks. With models, we show that the rate of the decay varies throughout the evolution of the disks, increasing its rate up to a certain point, which is followed by a leveling off to a slower value. The total disk mass falls off {prop.to}t^-0.35^ at its fastest point (where t is time) for our reference model, while the dust mass and its proxy -the infrared excess emission- fades significantly faster ({prop.to}t^-0.8^). These later level off to a decay rate of M_tot_(t){prop.to}t^-0.08^ and M_dust_(t) or L_ir_(t){prop.to}t^-0.6^. This is slower than the {prop.to}t.^-1^ decay given for all three system parameters by traditional analytic models. We also compile an extensive catalog of Spitzer and Herschel 24, 70, and 100{mu}m observations. Assuming a log-normal distribution of initial disk masses, we generate model population decay curves for the fraction of stars harboring debris disks detected at 24{mu}m. We also model the distribution of measured excesses at the far-IR wavelengths (70-100{mu}m) at certain age regimes. We show general agreement at 24{mu}m between the decay of our numerical collisional population synthesis model and observations up to a Gyr. We associate offsets above a Gyr to stochastic events in a few select systems. We cannot fit the decay in the far-infrared convincingly with grain strength properties appropriate for silicates, but those of water ice give fits more consistent with the observations (other relatively weak grain materials would presumably also be successful). The oldest disks have a higher incidence of large excesses than predicted by the model; again, a plausible explanation is very late phases of high dynamical activity around a small number of stars. Finally, we constrain the variables of our numerical model by comparing the evolutionary trends generated from the exploration of the full parameter space to observations. Amongst other results, we show that erosive collisions are dominant in setting the timescale of the evolution and that planetesimals on the order of 100 km in diameter are necessary in the cascades for our population synthesis models to reproduce the observations.
- ID:
- ivo://CDS.VizieR/J/ApJ/685/1005
- Title:
- Spitzer and high-mass star forming regions
- Short Name:
- J/ApJ/685/1005
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Spitzer Space Telescope IRAC and MIPS observations toward a sample of nine high-mass star forming regions at a distance of around 2kpc. Based on IRAC and MIPS 24um photometric results and 2MASS JHKs data, we carry out a census of young stellar objects (YSOs) in a 5'x5' field toward each region. Toward seven out of the nine regions, we detect parsec-sized clusters with around 20 YSOs surrounded by a more extended and sparse distribution of young stars and protostars. For the other two regions, IRAS 20126+4104 and IRAS 22172+5549, the former has the lowest number of YSOs in the sample and shows no obvious cluster, and the latter appears to be part of a larger, potentially more evolved cluster.
- ID:
- ivo://CDS.VizieR/J/ApJ/778/96
- Title:
- Spitzer and NEWFIRM observations of NGC 6334
- Short Name:
- J/ApJ/778/96
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper presents a study of the rate and efficiency of star formation in the NGC 6334 star-forming region. We obtained observations at J, H, and K_s_ taken with the NOAO Extremely Wide-Field Infrared Imager and combined them with observations taken with the Infrared Array Camera (IRAC) on the Spitzer Space Telescope at wavelengths = 3.6, 4.5, 5.8, and 8.0{mu}m. We also analyzed previous observations taken at 24{mu}m using the Spitzer MIPS camera as part of the MIPSGAL survey. We have produced a point source catalog with >700000 entries. We have identified 2283 young stellar object (YSO) candidates, 375 Class I YSOs, and 1908 Class II YSOs using a combination of existing IRAC-based color classification schemes that we have extended and validated to the near-IR for use with warm Spitzer data. We have identified multiple new sites of ongoing star formation activity along filamentary structures extending tens of parsecs beyond the central molecular ridge of NGC 6334. By mapping the extinction, we derived an estimate for the gas mass, 2.2x10^5^M_{sun}_. The heavy concentration of protostars along the dense filamentary structures indicates that NGC 6334 may be undergoing a "mini-starburst" event with {Sigma}_SFR_>8.2M_{sun}_M/yr/pc2 and SFE>0.10. We have used these estimates to place NGC 6334 in the Kennicutt-Schmidt diagram to help bridge the gap between observations of local low-mass star-forming regions and star formation in other galaxies.
- ID:
- ivo://CDS.VizieR/J/ApJ/805/77
- Title:
- Spitzer 3.6 and 4.5um monitoring of 5 stars
- Short Name:
- J/ApJ/805/77
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Luminous debris disks of warm dust in the terrestrial planet zones around solar-like stars were recently found to vary, which is indicative of ongoing large-scale collisions of rocky objects. We use Spitzer 3.6 and 4.5um time-series observations in 2012 and 2013 (extended to 2014 in one case) to monitor five more debris disks with unusually high fractional luminosities ("extreme debris disk"), including P1121 in the open cluster M47 (80 Myr), HD15407A in the AB Dor moving group (80Myr), HD 23514 in the Pleiades (120Myr), HD145263 in the Upper Sco Association (10Myr), and the field star BD+20 307 (>~1Gyr). Together with the published results for ID8 in NGC2547 (35Myr), this makes the first systematic time-domain investigation of planetary impacts outside the solar system. Significant variations with timescales shorter than a year are detected in five out of the six extreme debris disks we monitored. However, different systems show diverse sets of characteristics in the time domain, including long-term decay or growth, disk temperature variations, and possible periodicity.
- ID:
- ivo://CDS.VizieR/J/AJ/131/250
- Title:
- Spitzer 70 and 160um observations in xFLS
- Short Name:
- J/AJ/131/250
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present 70 and 160{mu}m observations from the Spitzer extragalactic First Look Survey (xFLS). The data reduction techniques and the methods for producing co-added mosaics and source catalogs are discussed. Currently, 26% of the 70{mu}m sample and 49% of the 160{mu}m-selected sources have redshifts. The majority of sources with redshifts are star-forming galaxies at z<0.5, while about 5% have infrared colors consistent with active galactic nuclei. The observed infrared colors agree with the spectral energy distributions (SEDs) of local galaxies previously determined from IRAS and Infrared Space Observatory data.
- ID:
- ivo://CDS.VizieR/J/AJ/151/90
- Title:
- Spitzer and VRIJHK photometry of V582 Mon
- Short Name:
- J/AJ/151/90
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We examine the light and color evolution of the T Tauri binary KH 15D through photometry obtained at wavelengths between 0.55 and 8.0{mu}m. The data were collected with A Novel Dual Imaging CAMera (ANDICAM) on the 1.3m SMARTS telescope at Cerro-Tololo Inter-American Observatory and with InfraRed Array Camera on the Spitzer Space Telescope. We show that the system's circumbinary ring, which acts as a screen that covers and uncovers different portions of the binary orbit as the ring precesses, has reached an orientation where the brighter component (star B) fully or nearly fully emerges during each orbital cycle. The fainter component (star A) remains fully occulted by the screen at all phases. The leading and trailing edges of the screen move across the sky at the same rate of ~15m/s, consistent with expectation for a ring with a radius and width of ~4 au and a precession period of ~6500 years. Light and color variations continue to indicate that the screen is sharp edged and opaque at VRIJH wavelengths. However, we find an increasing transparency of the ring edge at 2.2, 3.6, and 4.5{mu}m. Reddening seen at the beginning of the eclipse that occurred during the CSI 2264 campaign particularly suggests selective extinction by a population of large dust grains. Meanwhile, the gradual bluing observed while star B is setting is indicative of forward scattering effects at the edge of the ring. The spectral energy distribution of the system at its bright phase shows no evidence of infrared excess emission that can be attributed to radiation from the ring or other dust component out to 8{mu}m.
