- ID:
- ivo://CDS.VizieR/J/A+A/617/A83
- Title:
- MIDI atlas of low- and intermediate-mass YSOs
- Short Name:
- J/A+A/617/A83
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Protoplanetary disks show large diversity regarding their morphology and dust composition. With mid-infrared interferometry the thermal emission of disks can be spatially resolved, and the distribution and properties of the dust within can be studied. Our aim is to perform a statistical analysis on a large sample of 82 disks around low- and intermediate-mass young stars, based on mid-infrared interferometric observations. We intend to study the distribution of disk sizes, variability, and the silicate dust mineralogy. Archival mid-infrared interferometric data from the MIDI instrument on the Very Large Telescope Interferometer are homogeneously reduced and calibrated. Geometric disk models are used to fit the observations to get spatial information about the disks. An automatic spectral decomposition pipeline is applied to analyze the shape of the silicate feature. We present the resulting data products in the form of an atlas, containing N band correlated and total spectra, visibilities, and differential phases. The majority of our data can be well fitted with a continuous disk model, except for a few objects, where a gapped model gives a better match. From the mid-infrared size-luminosity relation we find that disks around T Tauri stars are generally colder and more extended with respect to the stellar luminosity than disks around Herbig Ae stars. We find that in the innermost part of the disks (r<~1au) the silicate feature is generally weaker than in the outer parts, suggesting that in the inner parts the dust is substantially more processed. We analyze stellar multiplicity and find that in two systems (AB Aur and HD 72106) data suggest a new companion or asymmetric inner disk structure. We make predictions for the observability of our objects with the upcoming Multi-AperTure mid- Infrared SpectroScopic Experiment (MATISSE) instrument, supporting the practical preparations of future MATISSE observations of T Tauri stars.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/545/A56
- Title:
- Mid-infrared diameter of 4 AGBs
- Short Name:
- J/A+A/545/A56
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Asymptotic giant branch (AGB) stars are one of the largest distributors of dust into the interstellar medium. However, the wind formation mechanism and dust condensation sequence leading to the observed high mass-loss rates have not yet been constrained well observationally, in particular for oxygen-rich AGB stars. The immediate objective in this work is to identify molecules and dust species which are present in the layers above the photosphere, and which have emission and absorption features in the mid-infrared (IR), causing the diameter to vary across the N- band, and are potentially relevant for the wind formation. Mid-IR (8-13 micron) interferometric data of four oxygen-rich AGB stars (R Aql, R Aqr, R Hya, and W Hya) and one carbon-rich AGB star (V Hya) were obtained with MIDI/VLTI between April 2007 and September 2009. The spectrally dispersed visibility data are analyzed by fitting a circular fully limb-darkened disk (FDD). The FDD diameter as function of wavelength is similar for all oxygen-rich stars. The apparent size is almost constant between 8 and 10 micron and gradually increases at wavelengths longer than 10 micron. The apparent FDD diameter in the carbon-rich star V Hya essentially decreases from 8 to 12 micron. The FDD diameters are about 2.2 times larger than the photospheric diameters estimated from K-band observations found in the literature. The silicate dust shells of R Aql, R Hya and W Hya are located fairly far away from the star, while the silicate dust shell of R Aqr and the amorphous carbon (AMC) and SiC dust shell of V Hya are found to be closer to the star at around 8 photospheric radii. Phase-to-phase variations of the diameters of the oxygen-rich stars could be measured and are on the order of 15% but with large uncertainties. From a comparison of the diameter trend with the trends in RR Sco and S Ori it can be concluded that in oxygen-rich stars the overall larger diameter originates from a warm molecular layer of H2O, and the gradual increase longward of 10 micron can be most likely attributed to the contribution of a close Al2O3 dust shell. The chromatic trend of the Gaussian FWHM in V Hya can be explained with the presence of AMC and SiC dust. The observations suggest that the formation of amorphous Al2O3 in oxygen-rich stars occurs mainly around or after visual minimum. However, no firm conclusions can be drawn concerning the mass-loss mechanism. Future modeling with hydrostatic and self-consistent dynamical stellar atmospheric models will be required for a more certain understanding.
- ID:
- ivo://CDS.VizieR/J/A+A/530/A120
- Title:
- Mid-infrared diameter of W Hya
- Short Name:
- J/A+A/530/A120
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Mid-infrared (N-band) interferometric data of W Hya were obtained with MIDI/VLTI between April 2007 and September 2009, covering nearly three pulsation cycles. The spectrally dispersed visibility data of all 75 observations were analyzed by fitting a circular fully limb-darkened disk (FDD) model to all data and individual pulsation phases. Asymmetries were studied with an elliptical FDD. Modeling results in an apparent angular FDD diameter of W Hya of about (80+/-1.2)mas (7.8AU) between 8 and 10 micron, which corresponds to an about 1.9 times larger diameter than the photospheric one. The diameter gradually increases up to (105+/-1.2)mas (10.3AU) at 12 micron. In contrast, the FDD relative flux fraction decreases from (0.85+/-0.02) to (0.77+/-0.02), reflecting the increased flux contribution from a fully resolved surrounding silicate dust shell. The asymmetric character of the extended structure could be confirmed. An elliptical FDD yields a position angle of (11+/-20)deg and an axis ratio of (0.87+/-0.07). A weak pulsation dependency is revealed with a diameter increase of (5.4+/-1.8)mas between visual minimum and maximum, while detected cycle-to-cycle variations are smaller.
- ID:
- ivo://CDS.VizieR/J/A+A/445/971
- Title:
- Mid-infrared images of W75N
- Short Name:
- J/A+A/445/971
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- An infrared study that includes ground-based mid-infrared images between 8.7 and 18.7um and IRAC images at 3.6, 4.5, 5.8 and 8.0um of the W75 N massive star forming region is presented. The 12.5um image shows the presence of four mid-infrared sources in the region W75 N(B), three of which have bright near-infrared counterparts, IRS 1, IRS 2 and IRS 3, all with significant excess emission at lambda>2.0um. IRS 2 has a steep energy distribution and the computed infrared luminosity is consistent with the presence of a young B3 star. The observed IRAC colors of IRS 3 indicate that this source is a Class II intermediate mass young star, consistent with its infrared energy distribution and luminosity. The fourth, newly discovered, mid-infrared source appears coincident with the ultracompact HII region VLA 3, and is located within the millimeter core MM 1. We derived a luminosity of ~750L_{sun}_ and a visual extinction A_V_~90 for this source. From the IRAC images, we detected 75 sources in an area of 120"x120" centered in W75 N. At least 25 of these sources are associated with the molecular cloud and form a young stellar cluster as shown in the IRAC two-color and the H-Ks versus Ks-[3.6] diagrams.
- ID:
- ivo://CDS.VizieR/J/ApJS/201/11
- Title:
- Mid-infrared spectral variability atlas of YSOs
- Short Name:
- J/ApJS/201/11
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The atlas presents medium-resolution mid-infrared spectra of low- and intermediate mass pre-main sequence objects obtained by the ISOPHOT-S spectrophotometer of the Infrared Space Observatory (ISO) and the Infrared Spectrograph (IRS) of the Spitzer Space Telescope.
- ID:
- ivo://CDS.VizieR/J/A+A/470/191
- Title:
- Mid-IR and radio interferometry of S Ori
- Short Name:
- J/A+A/470/191
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first multi-epoch study that includes concurrent mid-infrared and radio interferometry of an oxygen-rich Mira star. We obtained mid-infrared interferometry of S Ori with VLTI/MIDI at four epochs in December 2004, February/March 2005, November 2005, and December 2005. We concurrently observed v=1, J=1-0 (43.1GHz) and v=2, J=1-0 (42.8GHz) SiO maser emission toward S Ori with the VLBA in January, February, and November 2005. The MIDI data are analyzed using self-excited dynamic model atmospheres including molecular layers, complemented by a radiative transfer model of the circumstellar dust shell. The VLBA data are reduced to the spatial structure and kinematics of the maser spots. The modeling of our MIDI data results in phase-dependent continuum photospheric angular diameters of 9.0+/-0.3mas (phase 0.42), 7.9+/-0.1mas (0.55), 9.7+/-0.1mas (1.16), and 9.5+/-0.4mas (1.27). The dust shell can best be modeled with Al2O3 grains alone using phase-dependent inner boundary radii between 1.8 and 2.4 photospheric radii. The dust shell appears to be more compact with larger optical depth near visual minimum (tau_V_~2.5), and more extended with lower optical depth after visual maximum (tau_V_~1.5). The ratios of the 43.1GHz/42.8GHz SiO maser ring radii to the photospheric radii are 2.2+/-0.3/2.1+/-0.2 (phase 0.44), 2.4+/-0.3/2.3+/-0.4 (0.55), and 2.1+/-0.3/1.9+/-0.2 (1.15). The maser spots mark the region of the molecular atmospheric layers shortly outward of the steepest decrease of the mid-infrared model intensity profile. Their velocity structure indicates a radial gas expansion. S Ori shows significant phase-dependences of photospheric radii and dust shell parameters. Al2O3 dust grains and SiO maser spots form at relatively small radii of ~1.8-2.4 photospheric radii. Our results suggest increased mass-loss and dust formation close to the surface near minimum visual phase, when Al2O3 dust grains are co-located with the molecular gas and the SiO maser shells, and a more expanded dust shell after visual maximum. Silicon does not appear to be bound in dust, as our data shows no sign of silicate grains.
- ID:
- ivo://CDS.VizieR/J/ApJ/731/90
- Title:
- Mid-IR content of BGPS sources
- Short Name:
- J/ApJ/731/90
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a search for mid-infrared signs of star formation activity in the 1.1mm sources in the Bolocam Galactic Plane Survey (BGPS). We have correlated the BGPS catalog (Cat. J/ApJS/188/123) with available mid-IR Galactic plane catalogs based on the Spitzer Space Telescope GLIMPSE legacy survey (including Cat. J/AJ/136/2413 and the EGO cat. J/AJ/136/2391) and the Midcourse Space Experiment (MSX) Galactic plane survey (RMS catalog, Hoare et al. 2004ASPC..317..156H). We find that 44% (3712 of 8358) of the BGPS sources contain at least one mid-IR source, including 2457 of 5067 (49%) within the area where all surveys overlap (10{deg}<l<65{deg}). Accounting for chance alignments between the BGPS and mid-IR sources, we conservatively estimate that 20% of the BPGS sources within the area where all surveys overlap show signs of active star formation. We separate the BGPS sources into four groups based on their probability of star formation activity. Extended Green Objects and Red MSX Sources make up the highest probability group, while the lowest probability group is comprised of "starless" BGPS sources which were not matched to any mid-IR sources. The mean 1.1mm flux of each group increases with increasing probability of active star formation.
- ID:
- ivo://CDS.VizieR/J/ApJ/725/2270
- Title:
- Mid-IR emission lines in AGNs
- Short Name:
- J/ApJ/725/2270
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We used Spitzer/Infrared Spectrograph spectroscopic data on 426 galaxies including quasars, Seyferts, LINERs, and HII galaxies to investigate the relationship among the mid-IR emission lines. There is a tight linear correlation between the [NeV]14.3um and 24.3um (97.1eV) and the [OIV]25.9um (54.9eV) high-ionization emission lines. The correlation also holds for these high-ionization emission lines and the [NeIII]15.56um (41eV) emission line, although only for active galaxies. We used these correlations to calculate the [NeIII] excess due to star formation in Seyfert galaxies. We also estimated the [OIV] luminosity due to star formation in active galaxies and determined that it dominates the [OIV] emission only if the contribution of the active nucleus to the total luminosity is below 5%. We find that the active galactic nucleus dominates the [OIV] emission in most Seyfert galaxies, whereas star formation adequately explains the observed [OIV] emission in optically classified HII galaxies. Finally, we computed photoionization models to determine the physical conditions of the narrow-line region where these high-ionization lines originate. The estimated ionization parameter range is -2.8<logU<-2.5 and the total hydrogen column density range is 20<logn_H_(cm^-2^)<21.
- ID:
- ivo://CDS.VizieR/J/ApJ/630/381
- Title:
- Mid-IR imaging in {rho} Oph
- Short Name:
- J/ApJ/630/381
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Results of a comprehensive, new, ground-based mid-infrared imaging survey of the young stellar population of the {rho} Ophiuchi cloud are presented. Data were acquired at the Palomar 5m and at the Keck 10m telescopes with the MIRLIN (Mid-InfraRed Large-well Imager) and LWS (Long Wavelength Spectrometer centered at 12.5{mu}m) instruments, at 0.5" and 0.25" resolutions, respectively. Of 172 survey objects, 85 were detected. Among the 22 multiple systems observed, 15 were resolved and their individual component fluxes determined.
- ID:
- ivo://CDS.VizieR/J/ApJ/719/1191
- Title:
- Mid-IR indicators of SF and AGN in galaxies
- Short Name:
- J/ApJ/719/1191
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the use of mid-infrared (MIR) polycyclic aromatic hydrocarbon (PAH) bands, the continuum, and emission lines as probes of star formation (SF) and active galactic nucleus (AGN) activity in a sample of 100 "normal" and local (z~0.1) emission-line galaxies. The MIR spectra were obtained with the Spitzer Space Telescope Infrared Spectrograph as part of the Spitzer-SDSS-GALEX Spectroscopic Survey (SSGSS), which includes multi-wavelength photometry from the ultraviolet to the far-infrared and optical spectroscopy. The continuum and features were extracted using PAHFIT, a decomposition code which we find to yield PAH equivalent widths (EWs) up to ~30 times larger than the commonly used spline methods. Despite the lack of extreme objects in our sample (such as strong AGNs, low-metallicity galaxies, or ULIRGs), we find significant variations in PAH, continuum, and emission-line properties, and systematic trends between these MIR properties and optically derived physical properties, such as age, metallicity, and radiation field hardness. We revisit the diagnostic diagram relating PAH EWs and [NeII]12.8um/[OIV]25.9um line ratios and find it to be in much better agreement with the standard optical SF/AGN classification than when spline decompositions are used, while also potentially revealing obscured AGNs.
