- ID:
- ivo://CDS.VizieR/J/A+A/637/A12
- Title:
- Northern disk of M31 XMM-Newton images
- Short Name:
- J/A+A/637/A12
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use new deep XMM-Newton observations of the northern disk of M31 to trace the hot interstellar medium (ISM) in unprecedented detail and to characterise the physical properties of the X-ray emitting plasmas. We used all XMM-Newton data up to and including our new observations to produce the most detailed image yet of the hot ISM plasma in a grand design spiral galaxy such as our own. We compared the X-ray morphology to multi-wavelength studies in the literature to set it in the context of the multi-phase ISM. We performed spectral analyses on the extended emission using our new observations as they offer sufficient depth and count statistics to constrain the plasma properties. Data from the Panchromatic Hubble Andromeda Treasury were used to estimate the energy injected by massive stars and their supernovae. We compared these results to the hot gas properties. The brightest emission regions were found to be correlated with populations of massive stars, notably in the 10kpc star-forming ring. The plasma temperatures in the ring regions are ~0.2keV up to ~0.6keV. We suggest this emission is hot ISM heated in massive stellar clusters and superbubbles. We derived X-ray luminosities, densities, and pressures for the gas in each region. We also found large extended emission filling low density gaps in the dust morphology of the northern disk, notably between the 5kpc and 10kpc star-forming rings. We propose that the hot gas was heated and expelled into the gaps by the populations of massive stars in the rings. It is clear that the massive stellar populations are responsible for heating the ISM to X-ray emitting temperatures, filling their surroundings, and possibly driving the hot gas into the low density regions. Overall, the morphology and spectra of the hot gas in the northern disk of M 31 is similar to other galaxy disks.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/644/A73
- Title:
- Nulling of 20 pulsars
- Short Name:
- J/A+A/644/A73
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Most of pulsar nulling observations were conducted at frequencies lower than 1400MHz. We aim to understand the nulling behaviors of pulsars at relatively high frequency, and to check if nulling is caused by a global change of pulsar magnetosphere. 20 bright pulsars are observed at 2250MHz with unprecedented lengths of time by using Jiamusi 66m telescope. Nulling fractions of these pulsars are estimated, and the null and emission states of pulses are identified. Nulling degrees and scales of the emission-null pairs are calculated to describe the distributions of emission and null lengths. Three pulsars, PSRs J0248+6021, J0543+2329 and J1844+00, are found to null for the first time. The details of null-to-emission and emission-to-null transitions within pulse window are first observed for PSR J1509+5531, which is a small probability event. A complete cycle of long nulls for hours is observed for PSR J1709-1640. For most of these pulsars, the K-S tests of nulling degrees and nulling scales reject the hypothesis that null and emission are of random processes at high significance levels. Emission-null sequences of some pulsars exhibit quasi-periodic, low-frequency or featureless modulations, which might be related to different origins. During transitions between emission and null states, pulse intensities have diverse tendencies for variations. Significant correlations are found for nulling fraction, nulling cadence and nulling scales with the energy loss rate of the pulsars. Combined with the nulling fractions reported in literatures for 146 nulling pulsars, we found that statistically large nulling fractions are more tightly related to pulsar period than to characteristic age or energy loss rate.
- ID:
- ivo://CDS.VizieR/J/ApJ/880/138
- Title:
- Observed transitions of CH_3_OH and CH_3_CHO
- Short Name:
- J/ApJ/880/138
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- IRAM 30m Observations toward eight protostellar outflow sources were taken in the 96-176GHz range. Transitions of CH_3_OH and CH_3_CHO were detected in seven of them. The integrated emissions of the transitions of each species that fell into the observed frequency range were measured and fit using RADEX and LTE models. Column densities and gas properties inferred from this fitting are presented. The ratio of the A and E-type isomers of CH_3_OH indicates that the methanol observed in these outflows was formed on the grain surface. Both species demonstrate a reduction of terminal velocity in their line profiles in faster outflows, indicating destruction in the post-shock gas phase. This destruction, and a near constant ratio of the CH_3_OH and CH_3_CHO column densities, imply it is most likely that CH_3_CHO also forms on the grain surface.
- ID:
- ivo://CDS.VizieR/J/A+A/655/L2
- Title:
- OGHReS 12CO(2-1) data cubes
- Short Name:
- J/A+A/655/L2
- Date:
- 10 Mar 2022 07:17:54
- Publisher:
- CDS
- Description:
- Filaments are a ubiquitous morphological feature of the molecular interstellar medium and are identified as sites of star formation. In recent years, more than 100 large-scale filaments (with length >10pc) have been observed in the inner Milky Way. As they appear linked to Galactic dynamics, studying those structures represents an opportunity to link kpc-scale phenomena to the physics of star formation, which operates on much smaller scales. In this letter, we use newly acquired Outer Galaxy High Resolution Survey (OGHReS) ^12^CO(2-1) data to demonstrate that a significant number of large-scale filaments are present in the outer Galaxy as well. The 37 filaments identified appear tightly associated to inter-arm regions. In addition, their masses and linear masses are, on average, one order of magnitude lower than similar-sized molecular filaments located in the inner Galaxy, showing that Milky Way dynamics is able to create very elongated features in spite of the lower gas supply in the Galactic outskirts.
- ID:
- ivo://CDS.VizieR/J/A+A/459/85
- Title:
- O/H and gas densities in star-forming galaxies
- Short Name:
- J/A+A/459/85
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Generally the gas metallicity in distant galaxies can only be inferred by using a few prominent emission lines. Various theoretical models have been used to predict the relationship between emission line fluxes and metallicity, suggesting that some line ratios can be used as diagnostics of the gas metallicity in galaxies. However, accurate empirical calibrations of these emission line flux ratios from real galaxy spectra spanning a wide metallicity range are still lacking. In this paper we provide such empirical calibrations by using the combination of two sets of spectroscopic data: one consisting of low-metallicity galaxies with a measurement of [O III]{lambda}4363 taken from the literature, including spectra from the Sloan Digital Sky Survey (SDSS), and the other one consisting of galaxies in the SDSS database whose gas metallicity has been determined from various strong emission lines in their spectra. This combined data set constitutes the largest sample of galaxies with information on the gas metallicity available so far and spanning the widest metallicity range. By using these data we obtain accurate empirical relations between gas metallicity and several emission line diagnostics, including the R23 parameter, the [NII]{lambda}6584/H{alpha} and [O III]{lambda}5007/[NII]{lambda}6584 ratios.
496. OH masers in W3(OH)
- ID:
- ivo://CDS.VizieR/J/ApJ/668/331
- Title:
- OH masers in W3(OH)
- Short Name:
- J/ApJ/668/331
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Recent studies of methanol and ground-state OH masers at very high spectral resolution have shed new light on small-scale maser processes. The nearby source W3(OH), which contains numerous bright masers in several different transitions, provides an excellent laboratory for high spectral resolution techniques. We present a model of W3(OH) based on European VLBI Network (EVN) observations of the rotationally excited 6030 and 6035MHz OH masers taken at 0.024km/s spectral resolution.
- ID:
- ivo://CDS.VizieR/J/A+A/582/A118
- Title:
- OH-streamer in SgrA at 1665 and 1667MHz
- Short Name:
- J/A+A/582/A118
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the structure and kinematics of the OH-streamer and the +80km/s cloud and their interactions with the circumnuclear disk (CND) and with other molecular clouds in the vicinity of the Galactic centre (GC), and we map OH absorption at about 6" resolution at R<=10pc from the GC, with about 9km/s of velocity resolution. The VLA was used to map OH line absorption at the 1665 and 1667MHz lambda doublet main lines of the ^2^{PI}_3/2_ state towards the Sagittarius A complex.
- ID:
- ivo://CDS.VizieR/J/ApJ/872/55
- Title:
- OI, GeII, KrI & H abundances from HST UV spectra
- Short Name:
- J/ApJ/872/55
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In a survey of archived ultraviolet spectra of 100 stars recorded by the echelle spectrograph of the Space Telescope Imaging Spectrograph on the Hubble Space Telescope, we measure the strengths of the weak absorption features of OI, GeII, and KrI in the interstellar medium. Our objective is to undertake an investigation that goes beyond earlier abundance studies to see how these elements are influenced independently by three different environmental properties: (1) values of a generalized atomic depletion factor F_*_ due to condensations onto dust grains (revealed here by the abundances of Mg and Mn relative to H), (2) the fraction of H atoms in the form of H_2_/f(H_2_), and (3) the ambient intensity I of ultraviolet starlight relative to an average value in our part of the Galaxy I_0_. As expected, the gas-phase abundances of all three elements exhibit negative partial correlations with F*. The abundances of free O atoms show significant positive partial correlations with logf(H_2_) and log(I/I_0_), while Ge and Kr exhibit negative partial correlations with log(I/I_0_) at marginal levels of significance. After correcting for these trends, the abundances of O relative to H show no significant variations with location, except for the already-known radial gradient of light-element abundances in the Milky Way. A comparison of Ge and O abundances revealed no significant regional enhancements or deficiencies of neutron-capture elements relative to {alpha}-process ones.
- ID:
- ivo://CDS.VizieR/VII/106
- Title:
- Open Cluster Interstellar Matter Database
- Short Name:
- VII/106
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This catalog is a compilation of the characteristics of 128 open clusters and the interstellar medium associated with them. It is distributed as the "OCISM Database" which is the set of data files, processing and analysis software written in FORTRAN, and the supporting documentation. As provided by the author, the data are in a multi-record format which is best accessed with the author's software. The clusters in this database have been relatively well-studied, have declinations greater than -20 deg., are between 1 and 5 kpc distant, and are younger than 100 million years old. Characteristics compiled for these clusters include cluster identification, spatial coordinates, radial velocities (of stellar clusters, H II regions, and molecular clouds), proper motions, distance, angular diameter, linear diameter, age, mass (based on stellar and atomic gas, ionized gas, molecular clouds, and dust determinations), visual extinction, and reddening.
500. Oph A mosaic image
- ID:
- ivo://CDS.VizieR/J/A+A/631/A58
- Title:
- Oph A mosaic image
- Short Name:
- J/A+A/631/A58
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Observations of young stellar objects (YSOs) in centimeter bands can probe the continuum emission from growing dust grains, ionized winds, and magnetospheric activity, which are intimately connected to the evolution of protoplanetary disks and the formation of planets. We have carried out sensitive continuum observations toward the Ophiuchus A star-forming region using the Karl G. Jansky Very Large Array (VLA) at 10GHz over a field-of-view of 6' with a spatial resolution of {theta}_maj_x{theta}_min_~0.4"x0.2". We achieved a 5{mu}Jy/beam root-mean-square noise level at the center of our mosaic field of view. Among the eighteen sources we detected, sixteen are YSOs (three Class 0, five Class I, six Class II, and two Class III) and two are extragalactic candidates.We find that thermal dust emission generally contributes less that 30% of the emission at 10GHz. The radio emission is dominated by other types of emission such as gyro-synchrotron radiation from active magnetospheres, free-free emission from thermal jets, free-free emission from the outflowing photo-evaporated disk material, and/or synchrotron emission from accelerated cosmic-rays in jet or protostellar surface shocks. These different types of emission could not be clearly disentangled. Our non-detections towards Class II/III disks suggest that extreme UV-driven photoevaporation is insufficient to explain the disk dispersal, assuming that the contribution of UV photoevaporating stellar winds to radio flux does not evolve with time. The sensitivity of our data cannot exclude photoevaporation due to X-ray photons as an efficient mechanism for disk dispersal. Deeper surveys with the Square Kilometre Array will be able to provide strong constraints on disk photoevaporation.
