- ID:
- ivo://CDS.VizieR/J/MNRAS/437/391
- Title:
- IR excess in Sun-like stars observed by WISE
- Short Name:
- J/MNRAS/437/391
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a search for infrared-excess (IR-excess) candidates in a comprehensive (29000 stars) magnitude-limited sample of dwarf stars, spanning the spectral range F2-K0, and brighter than V=15mag. We searched the sample within the WISE all sky survey data base for objects within 1 arcsec of the coordinates provided by the SIMBAD data base, and found over 9000 sources detected in all WISE bands. The sample excludes objects that are flagged as extended sources and those images that are affected by various optical artefacts. For each detected object, we compared the observed W4/W2 (22{mu}m/4.6{mu}m) flux ratio with the expected photospheric value and identified 197 excess candidates at 3{sigma}. For the vast majority of candidates, the results of this analysis represent the first reported evidence of an IR excess. Through the comparison with a simple blackbody emission model, we derive estimates of the dust temperature, as well as of the dust fractional luminosities. For more than 80 percent of the sample, this temperature is higher than 120K, suggesting the presence of warm circumstellar dust. Complementary observations at longer wavelengths (far-IR and submillimetre) are required for better characterizing and explaining the origin of this emission.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/658/1264
- Title:
- IR-excess sources in GLIMPSE and MSX
- Short Name:
- J/ApJ/658/1264
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have identified 230 Tycho-2 Spectral Catalog stars that exhibit 8um mid-IR extraphotospheric excesses in the MSX and Spitzer GLIMPSE surveys. Of these, 183 are either OB stars earlier than B8 in which the excess plausibly arises from a thermal bremsstrahlung component or evolved stars in which the excess may be explained by an atmospheric dust component. The remaining 47 stars have spectral classifications B8 or later and appear to be main-sequence or late pre-main-sequence objects harboring circumstellar disks. Six of the 47 stars exhibit multiple signatures characteristic of pre-main-sequence circumstellar disks, including emission lines, near-IR K-band excesses, and X-ray emission. Approximately one-third of the remaining 41 sources have emission lines suggesting relative youth. We modeled the excesses in 26 stars having two or more measurements in excess of the expected photospheres as single-component blackbodies.
- ID:
- ivo://CDS.VizieR/J/ApJS/225/15
- Title:
- IR excess stars from Tycho-2 and AllWISE
- Short Name:
- J/ApJS/225/15
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The conclusion of the Wide-Field Infrared Survey Explorer (WISE) mission presents an opportune time to summarize the history of using excess emission in the infrared as a tracer of circumstellar material and exploit all available data for future missions such as the James Webb Space Telescope. We have compiled a catalog of infrared excess stars from peer-reviewed articles and perform an extensive search for new infrared excess stars by cross-correlating the Tycho-2 and all-sky WISE (AllWISE) catalogs. We define a significance of excess in four spectral type divisions and select stars showing greater than either 3{sigma} or 5{sigma} significance of excess in the mid- and far-infrared. Through procedures including spectral energy distribution fitting and various image analyses, each potential excess source was rigorously vetted to eliminate false positives. The infrared excess stars from the literature and the new stars found through the Tycho-2 and AllWISE cross-correlation produced nearly 500 "Prime" infrared excess stars, of which 74 are new sources of excess, and >1200 are "Reserved" stars, of which 950 are new sources of excess. The main catalog of infrared excess stars are nearby, bright, and either demonstrate excess in more than one passband or have infrared spectroscopy confirming the infrared excess. This study identifies stars that display a spectral energy distribution suggestive of a secondary or post-protoplanetary generation of dust, and they are ideal targets for future optical and infrared imaging observations. The final catalogs of stars summarize the past work using infrared excess to detect dust disks, and with the most extensive compilation of infrared excess stars (~1750) to date, we investigate various relationships among stellar and disk parameters.
- ID:
- ivo://CDS.VizieR/J/AJ/144/11
- Title:
- IR imaging, nuclear SEDs, Spitzer spectra of 22 AGNs
- Short Name:
- J/AJ/144/11
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present high-resolution mid-infrared (MIR) imaging, nuclear spectral energy distributions (SEDs), and archival Spitzer spectra for 22 low-luminosity active galactic nuclei (LLAGNs; L_bol_<~10^42^erg/s). Infrared (IR) observations may advance our understanding of the accretion flows in LLAGNs, the fate of the obscuring torus at low accretion rates, and, perhaps, the star formation histories of these objects. However, while comprehensively studied in higher-luminosity Seyferts and quasars, the nuclear IR properties of LLAGNs have not yet been well determined. We separate the present LLAGN sample into three categories depending on their Eddington ratio and radio emission, finding different IR characteristics for each class. (1) At the low-luminosity, low-Eddington-ratio (log L_bol_/L_Edd_< -4.6) end of the sample, we identify "host-dominated" galaxies with strong polycyclic aromatic hydrocarbon bands that may indicate active (circum-)nuclear star formation. (2) Some very radio-loud objects are also present at these low Eddington ratios. The IR emission in these nuclei is dominated by synchrotron radiation, and some are likely to be unobscured type 2 AGNs that genuinely lack a broad-line region. (3) At higher Eddington ratios, strong, compact nuclear sources are visible in the MIR images. The nuclear SEDs of these galaxies are diverse; some resemble typical Seyfert nuclei, while others lack a well-defined MIR "dust bump." Strong silicate emission is present in many of these objects. We speculate that this, together with high ratios of silicate strength to hydrogen column density, could suggest optically thin dust and low dust-to-gas ratios, in accordance with model predictions that LLAGNs do not host a Seyfert-like obscuring torus. We anticipate that detailed modeling of the new data and SEDs in terms of accretion disk, jet, radiatively inefficient accretion flow, and torus components will provide further insights into the nuclear structures and processes of LLAGNs.
- ID:
- ivo://CDS.VizieR/J/ApJ/679/140
- Title:
- IR measurement of quasar obscuration
- Short Name:
- J/ApJ/679/140
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Recent work has suggested that the fraction of obscured AGNs declines with increasing luminosity, but it has been difficult to quantify this trend. Here we attempt to measure this fraction as a function of luminosity by studying the ratio of mid-infrared to intrinsic nuclear bolometric luminosity in unobscured AGNs. Because the mid-infrared is created by dust reprocessing of shorter wavelength nuclear light, this ratio is a diagnostic of f_obsc_, the fraction of solid angle around the nucleus covered by obscuring matter. In order to eliminate possible redshift dependences while also achieving a large dynamic range in luminosity, we have collected archival 24um MIPS photometry from objects with z~1 in the Sloan Digital Sky Survey DR5, the Great Observatories Origins Deep Survey, and the Cosmic Evolution Survey. To measure the bolometric luminosity for each object, we used archival optical data supplemented by GALEX data.
- ID:
- ivo://CDS.VizieR/J/ApJ/596/748
- Title:
- IR Observations in HDF-North
- Short Name:
- J/ApJ/596/748
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The original analysis of the star formation history in the NICMOS deep images of the northern Hubble Deep Field (NHDF) is extended to the entire NHDF utilizing NICMOS and WFPC2 archival data. The roughly constant star formation rate from redshifts 16 found in this study is consistent with the original results. Star formation rates from this study, Lyman break galaxies, and submillimeter observations are now in concordance. The spike of star formation at redshift 2 due to two ultraluminous IR galaxies in the small deep NICMOS field is smoothed out in the larger area results presented here. The larger source base of this study allows comparison with predictions from hierarchical galaxy formation models. In general, the observation are consistent with the predictions. The observed luminosity functions at redshifts 16 are presented for future comparisons with theoretical galaxy evolution calculations. Mid- and far-infrared properties of the sources are also calculated and compared with observations. A candidate for the VLA source VLA 3651+1221 is discussed.
- ID:
- ivo://CDS.VizieR/J/ApJ/752/127
- Title:
- IR observations of AFGL 490
- Short Name:
- J/ApJ/752/127
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Spitzer IRAC and MIPS observations of the star-forming region containing intermediate-mass young stellar object (YSO) AFGL 490. We supplement these data with near-IR Two Micron All Sky Survey photometry and with deep Simultaneous Quad Infrared Imaging Device observations off the central high-extinction region. We have more than doubled the known membership of this region to 57 Class I and 303 Class II YSOs via the combined 1-24{mu}m photometric catalog derived from these data. We construct and analyze the minimum spanning tree of their projected positions, isolating one locally overdense cluster core containing 219 YSOs (60.8% of the region's members). We find this cluster core to be larger yet less dense than similarly analyzed clusters. Although the structure of this cluster core appears irregular, we demonstrate that the parsec-scale surface densities of both YSOs and gas are correlated with a power-law slope of 2.8, as found for other similarly analyzed nearby molecular clouds. We also explore the mass segregation implications of AFGL 490's offset from the center of its core, finding that it has no apparent preferential central position relative to the low-mass members.
- ID:
- ivo://CDS.VizieR/J/A+A/375/1
- Title:
- IR observations of Chandra Deep Field + HDF-South
- Short Name:
- J/A+A/375/1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present near-IR (J and Ks) number counts and colors of galaxies detected in deep VLT-ISAAC images centered on the Chandra Deep Field (03h 32min 16s, -27{deg} 47' 25") and on the Hubble Deep Field-South. (22h 32min 55s, -60{deg} 33' 08"). The data have been obtained with the ISAAC infrared imager/spectrometer at the ESO VLT-UT1 telescope on several nights from September to December 1999 (seeing conditions around 0.7arcsec). The limiting surface brightness (1 sigma) obtained is 24.5mag/arcsec^2^ in J and 22mag/arcsec^2^ in Ks.
- ID:
- ivo://CDS.VizieR/J/AJ/142/148
- Title:
- IR observations of galaxies in the Coma cluster
- Short Name:
- J/AJ/142/148
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a thorough study of the specific star formation rates (sSFRs) for MIPS 24um selected galaxies in the Coma cluster. We build galaxy spectral energy distributions using optical (u', g', r', i', z'), near-infrared (J, H, Ks), and mid- to far-infrared (Infrared Array Camera and MIPS) photometry. New and archival spectra confirm 210 cluster members. Subsequently, the total infrared luminosity, galaxy stellar mass, and sSFR for the members are determined by measuring best-fit templates. Using an array of complementary diagnostics, we search for any contaminating active galactic nuclei, but find few. We compare obscured SFRs to unobscured rates derived from extinction-corrected H{alpha} emission line measurements. The agreement between these two values leads us to conclude that there is no evidence for an additionally obscured component. In our spectroscopic sample, complete to 80% for r'<19.5, we find that all starbursts are blue and are dwarfs, having masses <10^9^M_{sun}_. Examining the location of these starbursts within the cluster, we confirm that there is a lower fraction in the cluster core.
- ID:
- ivo://CDS.VizieR/J/MNRAS/386/313
- Title:
- IR observations of Mira variables
- Short Name:
- J/MNRAS/386/313
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Published data for large-amplitude asymptotic giant branch variables in the Large Magellanic Cloud (LMC) are re-analysed to establish the constants for an infrared (K) period-luminosity relation of the form MK={rho}[logP-2.38]+{delta}. A slope of {rho}=-3.51+/-0.20 and a zero-point of {delta}=-7.15+/-0.06 are found for oxygen-rich Miras (if a distance modulus of 18.39+/-0.05 is used for the LMC). Assuming this slope is applicable to Galactic Miras we discuss the zero-point for these stars using the revised Hipparcos parallaxes together with published very long baseline interferometry (VLBI) parallaxes for OH masers and Miras in globular clusters. These result in a mean zero-point of {delta}=-7.25+/-0.07 for O-rich Galactic Miras. The zero-point for Miras in the Galactic bulge is not significantly different from this value.
