- ID:
- ivo://CDS.VizieR/J/AJ/155/81
- Title:
- Diffuse X-ray-emitting gas in major mergers
- Short Name:
- J/AJ/155/81
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using archived data from the Chandra X-ray telescope, we have extracted the diffuse X-ray emission from 49 equal-mass interacting/merging galaxy pairs in a merger sequence, from widely separated pairs to merger remnants. After the removal of contributions from unresolved point sources, we compared the diffuse thermal X-ray luminosity from hot gas (L_X_(gas)) with the global star formation rate (SFR). After correction for absorption within the target galaxy, we do not see a strong trend of L_X_(gas)/SFR with the SFR or merger stage for galaxies with SFR>1 M_{sun}_/yr. For these galaxies, the median L_X_(gas)/SFR is 5.5x10^39^ ((erg/s)/M_{sun}_/yr), similar to that of normal spiral galaxies. These results suggest that stellar feedback in star-forming galaxies reaches an approximately steady-state condition, in which a relatively constant fraction of about 2% of the total energy output from supernovae and stellar winds is converted into X-ray flux. Three late-stage merger remnants with low SFRs and high K-band luminosities (L_K_) have enhanced L_X_(gas)/SFR; their UV/IR/optical colors suggest that they are post-starburst galaxies, perhaps in the process of becoming ellipticals. Systems with L_K_<10^10^ L_{sun}_ have lower L_X_(gas)/SFR ratios than the other galaxies in our sample, perhaps due to lower gravitational fields or lower metallicities. We see no relation between L_X_(gas)/SFR and Seyfert activity in this sample, suggesting that feedback from active galactic nuclei is not a major contributor to the hot gas in our sample galaxies.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/625/A49
- Title:
- Dimming event of RW Aurigae A
- Short Name:
- J/A+A/625/A49
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- RW Aur A is a classical T Tauri star that has suddenly undergone three major dimming events since 2010. The reason for these dimming events is still not clear. The two epochs of observations uploaded here are on the deep dimming events (2015) and immediate after the dimmin event (2016).
- ID:
- ivo://CDS.VizieR/J/AJ/159/74
- Title:
- Disk-resolved photometric properties of Pluto
- Short Name:
- J/AJ/159/74
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A multiwavelength regionally dependent photometric analysis of Pluto's anti-Charon-facing hemisphere using images collected by New Horizons' Multispectral Visible Imaging Camera (MVIC) reveals large variations in the absolute value and spectral slope of the single-scattering albedo. Four regions of interest are analyzed: the dark equatorial belt, Pluto's north pole, nitrogen-rich regions, and the mid-latitude terrains. Regions dominated by volatile ices such as Lowell Regio and Sputnik Planitia present single-scattering albedos of ~0.98 at 492nm, almost neutral across MVIC's visible wavelength range (400-910nm), indicating limited contributions from tholin materials. Pluto's dark equatorial regions, informally named Cthulhu and Krun Maculae, have single-scattering albedos of ~0.16 at 492nm and are the reddest regions. Applying the Hapke radiative transfer model to combined MVIC and Linear Etalon Imaging Spectral Array (LEISA) spectra (400-2500nm) of Cthulhu Macula and Lowell Regio successfully reproduces the spectral properties of these two regions of dramatically disparate coloration, composition, and morphology. Since this model uses only a single coloring agent, very similar to the Titan like tholin of Khare+ (1984Icar...60..127K), to account for all of Pluto's colors, this result supports the Grundy+ (2016Sci...351.9189G) conclusion that Pluto's coloration is the result of photochemical products mostly produced in the atmosphere. Although cosmic rays and extreme ultraviolet photons reach Pluto's surface where they can drive chemical processing, observations of diverse surface colors do not require different chemical products produced in different environments. We report a correction scaling factor in the LEISA radiometric calibration of 0.74{+/-}0.05.
- ID:
- ivo://CDS.VizieR/J/A+A/631/A108
- Title:
- Disks around post-AGB binaries fit results
- Short Name:
- J/A+A/631/A108
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Post-asymptotic giant branch (pAGB) binaries are surrounded by circumbinary disks of gas and dust that are similar to protoplanetary disks found around young stars. We aim to understand the structure of these disks and identify the physical phenomena at play in their very inner regions. We want to understand the disk-binary interaction and to further investigate the comparison with protoplanetary disks. We conducted an interferometric snapshot survey of 23 post-AGB binaries in the near-infrared (H-band) using VLTI/PIONIER. We fit the multi-wavelength visibilities and closure phases with purely geometrical models with an increasing complexity (including two point-sources, an azimuthally modulated ring, and an over-resolved flux) in order to retrieve the sizes, temperatures, and flux ratios of the different components. All sources are resolved and the different components contributing to the H-band flux are dissected. The environment of these targets is very complex: 13/23 targets need models with thirteen or more parameters to fit the data. We find that the inner disk rims follow and extend the size-luminosity relation established for disks around young stars with an offset toward larger sizes. The measured temperature of the near-infrared circumstellar emission of post-AGB binaries is lower (Tsub~1200K) than for young stars, which is probably due to a different dust mineralogy and/or gas density in the dust sublimation region. The dusty inner rims of the circumbinary disks around post-AGB binaries are ruled by dust sublimation physics. Additionally a significant amount of the circumstellar $H$-band flux is over-resolved (more than 10% of the non-stellar flux is over-resolved in 14 targets). This hints that a source of unknown origin, either a disk structure or outflow. The amount of over-resolved flux is larger than around young stars. Due to the complexity of these targets, interferometric imaging is a necessary tool to reveal the interacting inner regions in a model-independent way.
- ID:
- ivo://CDS.VizieR/J/A+A/633/A82
- Title:
- Disks around T Tauri stars with SPHERE. II.
- Short Name:
- J/A+A/633/A82
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Near-IR polarimetric images of protoplanetary disks provide the ability to characterize sub-structures that are potentially due to the interaction with (forming) planets. The available census is, however, strongly biased toward massive disks around old stars. The DARTTS program aims at alleviating this bias by imaging a large number of T Tauri stars with diverse properties. DARTTS-S employs VLT/SPHERE to image the polarized scattered light from disks. In parallel, DARTTS-A is providing ALMA images of the same targets for a comparison of different dust components. In this work, we present new SPHERE images of 21 circumstellar disks, which is the largest sample of this time yet to be released. A re-calculation of some relevant stellar and disk properties following Gaia DR2 is also performed. The targets of this work are significantly younger than those published thus far with polarimetric NIR imaging. Scattered light is unambiguously resolved in 11 targets while some polarized unresolved signal is detected in 3 additional sources. Some disk sub-structures are detected. However, the paucity of spirals and shadows from this sample reinforces the trend for which these NIR features are associated with Herbig stars, either because older or more massive. Furthermore, disk rings that are apparent in ALMA observations of some targets do not appear to have corresponding detections with SPHERE. Inner cavities larger than 15au are also absent from our images despite being expected from the SED. On the other hand, 3 objects show extended filaments at larger scale that are indicative of strong interaction with the surrounding medium. All but one of the undetected disks are best explained by their limited size (<~20au) and the high occurrence of stellar companions in these sources suggest an important role in limiting the disk size. One undetected disk is massive and very large at millimeter wavelengths implying it is self-shadowed in the near-IR. This work paves the way towards a more complete and less biased sample of scattered-light observations, which is required to interpret how disk features evolve throughout the disk lifetime.
- ID:
- ivo://CDS.VizieR/J/ApJ/706/727
- Title:
- Distance and mass of Infrared Dark Clouds
- Short Name:
- J/ApJ/706/727
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Infrared Dark Clouds (IRDCs) are dark clouds seen in silhouette in mid-infrared surveys. They are thought to be the birthplace of massive stars, yet remarkably little information exists on the properties of the population as a whole (e.g., mass spectrum, spatial distribution). Genetic forward modeling is used along with the Two Micron All Sky Survey and the Besancon Galactic model to deduce the three-dimensional distribution of interstellar extinction toward previously identified IRDC candidates. This derived dust distribution can then be used to determine the distance and mass of IRDCs, independently of kinematic models of the Milky Way. Along a line of sight that crosses an IRDC, the extinction is seen to rise sharply at the distance of the cloud. Assuming a dust-to-gas ratio, the total mass of the cloud can be estimated. The method has been successfully applied to 1259 IRDCs, including over 1000 for which no distance or mass estimate currently exists. The IRDCs are seen to lie preferentially along the spiral arms and in the molecular ring of the Milky Way, reinforcing the idea that they are the birthplace of massive stars. Also, their mass spectrum is seen to follow a power law with an index of -1.75+/-0.06, steeper than giant molecular clouds (GMCs) in the inner Galaxy but comparable to clumps in GMCs. This slope suggests that the IRDCs detected using the present method are not gravitationally bound, but are rather the result of density fluctuations induced by turbulence.
- ID:
- ivo://CDS.VizieR/J/MNRAS/452/637
- Title:
- Distance-limited sample of MYSOs
- Short Name:
- J/MNRAS/452/637
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyse C^18^O (J=3-2) data from a sample of 99 infrared (IR)-bright massive young stellar objects (MYSOs) and compact HII regions that were identified as potential molecular-outflow sources in the Red MSX Source survey. We extract a distance-limited (D<6kpc) sample shown to be representative of star formation covering the transition between the source types. At the spatial resolution probed, Larson-like relationships are found for these cores, though the alternative explanation, that Larson's relations arise where surface-density-limited samples are considered, is also consistent with our data. There are no significant differences found between source properties for the MYSOs and HII regions, suggesting that the core properties are established prior to the formation of massive stars, which subsequently have little impact at the later evolutionary stages investigated. There is a strong correlation between dust-continuum and C^18^O-gas masses, supporting the interpretation that both trace the same material in these IR-bright sources. A clear linear relationship is seen between the independently established core masses and luminosities. The position of MYSOs and compact HII regions in the mass-luminosity plane is consistent with the luminosity expected from the most massive protostar in the cluster when using an ~40 percent star formation efficiency and indicates that they are at a similar evolutionary stage, near the end of the accretion phase.
- ID:
- ivo://CDS.VizieR/J/MNRAS/487/2061
- Title:
- Distances for 2062 nearby spiral galaxies
- Short Name:
- J/MNRAS/487/2061
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the final distance measurements for the 2MASS Tully-Fisher (2MTF) survey. The final 2MTF catalogue contains 2062 nearby spiral galaxies in the CMB frame velocity range of 600<cz<10000km/s with a mean velocity of 4805km/s. The main update in this release is the replacement of some archival HI data with newer ALFALFA data. Using the 2MTF template relation, we calculate the distances and peculiar velocities of all 2MTF galaxies. The mean uncertainties of the linear distance measurements are around 22 per cent in all three infrared bands. 2MTF measurements agree well with the distances from the Cosmicflows-3 compilation, which contains 1117 common galaxies, including 28 with SNIa distance measurements. Using distances estimated from the '3-bands combined' 2MTF sample and a {chi}^2^ minimization method, we find best-fitting bulk flow amplitudes of 308+/-26km/s, 318+/-29km/s, and 286+/-25km/s at depths of R_I_=20, 30 and 40h^-1^Mpc, respectively, which is consistent with the {LAMNDA}CDM model and with previous 2MTF results with different estimation techniques and a preliminary catalogue.
- ID:
- ivo://CDS.VizieR/J/AJ/115/1989
- Title:
- Distances of galactic planetary nebulae
- Short Name:
- J/AJ/115/1989
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- It is well known that the IRAS colors of planetary nebulae (PNe) are very similar to blackbody colors. Taking account of this characteristic, we define a new method to obtain some information about the distance to PNe by blackbody fitting of IRAS four-band fluxes, assuming these fluxes are due to thermal emission from the nebular dust envelope. The fit should have two free parameters - the dust temperature TD and the distance-dependent "scaling factor" A - under the assumption of uniform dust mass. We find that the A-values have a good correlation with published distances. The scaling factor A could be a more effective distance scale than others, because many PNe have been detected as IRAS sources and the extinction of IRAS fluxes is not so severe, and is known. We also find that TD is concentrated between 100 and 200K, with a typical value of about 150K.
- ID:
- ivo://CDS.VizieR/J/ApJ/838/107
- Title:
- Distances to RRab stars from WISE and Gaia
- Short Name:
- J/ApJ/838/107
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Pulsating stars, such as Cepheids, Miras, and RR Lyrae stars, are important distance indicators and calibrators of the "cosmic distance ladder," and yet their period-luminosity-metallicity (PLZ) relations are still constrained using simple statistical methods that cannot take full advantage of available data. To enable optimal usage of data provided by the Gaia mission, we present a probabilistic approach that simultaneously constrains parameters of PLZ relations and uncertainties in Gaia parallax measurements. We demonstrate this approach by constraining PLZ relations of type ab RR Lyrae stars in near-infrared W1 and W2 bands, using Tycho-Gaia Astrometric Solution (TGAS) parallax measurements for a sample of ~100 type ab RR Lyrae stars located within 2.5kpc of the Sun. The fitted PLZ relations are consistent with previous studies, and in combination with other data, deliver distances precise to 6% (once various sources of uncertainty are taken into account). To a precision of 0.05mas (1{sigma}), we do not find a statistically significant offset in TGAS parallaxes for this sample of distant RR Lyrae stars (median parallax of 0.8mas and distance of 1.4kpc). With only minor modifications, our probabilistic approach can be used to constrain PLZ relations of other pulsating stars, and we intend to apply it to Cepheid and Mira stars in the near future.
