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1781. NGC 1333-IRAS 4A C^18^O, NO and O_2_ spectra
ID:
ivo://CDS.VizieR/J/A+A/558/A58
Title:
NGC 1333-IRAS 4A C^18^O, NO and O_2_ spectra
Short Name:
J/A+A/558/A58
Date:
21 Oct 2021
Publisher:
CDS
Description:
According to traditional gas-phase chemical models, O_2_ should be abundant in molecular clouds, but until recently, attempts to detect interstellar O_2_ line emission with ground- and space-based observatories have failed. Following the multi-line detections of O_2_ with low abundances in the Orion and rho Oph A molecular clouds with Herschel, it is important to investigate other environments, and we here quantify the O_2_ abundance near a solar-mass protostar. Observations of molecular oxygen, O_2_, at 487GHz toward a deeply embedded low-mass Class 0 protostar, NGC 1333-IRAS 4A, are presented, using the Heterodyne Instrument for the Far Infrared (HIFI) on the Herschel Space Observatory. Complementary data of the chemically related NO and CO molecules are obtained as well. The high spectral resolution data are analysed using radiative transfer models to infer column densities and abundances, and are tested directly against full gas-grain chemical models. The deep HIFI spectrum fails to show O_2_ at the velocity of the dense protostellar envelope, implying one of the lowest abundance upper limits of O_2_/H_2_ at <6x10^-3^ (3 sigma). The O_2_/CO abundance ratio is less than 0.005. However, a tentative (4.5 sigma) detection of O_2_ is seen at the velocity of the surrounding NGC1333 molecular cloud, shifted by 1km/s relative to the protostar. For the protostellar envelope, pure gas-phase models and gas-grain chemical models require a long pre-collapse phase (~0.7-1x10^6^-years), during which atomic and molecular oxygen are frozen out onto dust grains and fully converted to H_2_O, to avoid overproduction of O_2_ in the dense envelope. The same model also reproduces the limits on the chemically related NO molecule if hydrogenation of NO on the grains to more complex molecules such as NH_2_OH, found in recent laboratory experiments, is included. The tentative detection of O_2_ in the surrounding cloud is consistent with a low-density PDR model with small changes in reaction rates. The low O_2_ abundance in the collapsing envelope around a low-mass protostar suggests that the gas and ice entering protoplanetary disks is very poor in O_2_.
1782. NGC 1333 IRAS 4A H_2_O observations
ID:
ivo://CDS.VizieR/J/A+A/568/A125
Title:
NGC 1333 IRAS 4A H_2_O observations
Short Name:
J/A+A/568/A125
Date:
21 Oct 2021
Publisher:
CDS
Description:
Water is a key molecule in protostellar environments because its line emission is very sensitive to both the chemistry and the physical conditions of the gas. Observations of H_2_O line emission from low-mass protostars and their associated outflows performed with HIFI onboard the Herschel Space Observatory have highlighted the complexity of H_2_O line profiles, in which different kinematic components can be distinguished. The goal is to study the spatial distribution of H_2_O, in particular of the different kinematic components detected in H_2_O emission, at two bright shocked regions along IRAS4A, one of the strongest H_2_O emitters among the Class 0 outflows. We obtained Herschel-PACS maps of the IRAS4A outflow and HIFI observations of two shocked positions. The largest HIFI beam of 38" at 557GHz was mapped in several key water lines with different upper energy levels, to reveal possible spatial variations of the line profiles. A large velocity gradient (LVG) analysis was performed to determine the excitation conditions of the gas.
1783. NGC4395 light curves. III.
ID:
ivo://CDS.VizieR/J/ApJ/650/88
Title:
NGC4395 light curves. III.
Short Name:
J/ApJ/650/88
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present optical observations of the low-luminosity Seyfert 1 nucleus of NGC 4395, as part of a multiwavelength reverberation-mapping program. Observations were carried out over two nights in 2004 April at Lick, Wise, and Kitt Peak Observatories. We obtained V- and B-band photometry, and spectra over the range 3500-6800{AA}. Simultaneous Hubble Space Telescope UV and Chandra X-ray observations are presented in companion papers.
1784. NGC 4151 line-continuum diagram sequences
ID:
ivo://CDS.VizieR/J/A+A/324/904
Title:
NGC 4151 line-continuum diagram sequences
Short Name:
J/A+A/324/904
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the first results of an 8-year spectroscopic monitoring of the Seyfert 1.5 galaxy NGC 4151 carried out with a CCD spectrograph at the 2.6-m Shajn Telescope of the Crimean Astrophysical Observatory in 1988-1995. Total of 202 H{ alpha} region spectra and 154 H{beta} region spectra have formed the data set. A ll spectra were calibrated in flux using the narrow emission lines which were as summed to be constant over the duration of the monitoring program.
1785. NGC6530 member parameters from Gaia-ESO survey
ID:
ivo://CDS.VizieR/J/A+A/623/A159
Title:
NGC6530 member parameters from Gaia-ESO survey
Short Name:
J/A+A/623/A159
Date:
21 Oct 2021
Publisher:
CDS
Description:
In very young clusters, stellar age distribution is the empirical proof of the duration of star formation (SF) and of the physical mechanisms involved in the process. We derived accurate stellar ages for the cluster NGC6530, associated with the Lagoon Nebula to infer its SF history. We use the Gaia-ESO survey observations and Gaia DR2 data, to derive cluster membership and fundamental stellar parameters. We identified 652 confirmed and 9 probable members. The reddening inferred for members and non-members allows us to distinguish MS stars and giants, in agreement with the distances inferred from Gaia DR2 data. The foreground and background stars show a spatial pattern that traces the 3D structure of the nebular dust component. We derive stellar ages for 382 confirmed cluster members and we find that the gravity-sensitive gamma index distribution for M stars is correlated with stellar age. For all members with Teff<5500K, the mean logarithmic age is 5.84 (units of years) with a dispersion of 0.36dex. The age distribution of stars with accretion and/or disk (CTTSe) is similar to that of stars without accretion and without disk (WTTSp). We interpret this dispersion as evidence of a real age spread since the total uncertainties on age determinations, derived from Monte Carlo simulations, are significantly smaller than the observed spread. This conclusion is supported by the evidence of a decreasing of the gravity-sensitive gamma index as a function of stellar ages. The presence of the age spread is also supported by the spatial distribution and the kinematics of old and young members. In particular, members with accretion and/or disk, formed in the last 1Myr, show evidence of subclustering around the cluster center, in the Hourglass Nebula and in the M8-E region, suggesting a possible triggering of star formation events by the O-type star ionization fronts.
1786. NGC 3115 MUSE images
ID:
ivo://CDS.VizieR/J/A+A/591/A143
Title:
NGC 3115 MUSE images
Short Name:
J/A+A/591/A143
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present MUSE integral field spectroscopic data of the S0 galaxy NGC 3115 obtained during the instrument commissioning at the ESO Very Large Telescope (VLT). We analyse the galaxy stellar kinematics and stellar populations and present two-dimensional maps of their associated quantities. We thus illustrate the capacity of MUSE to map extra-galactic sources to large radii in an efficient manner, i.e. ~4R_e_, and provide relevant constraints on its mass assembly. We probe the well-known set of substructures of NGC 3115 (nuclear disc, stellar rings, outer kpc-scale stellar disc, and spheroid) and show their individual associated signatures in the MUSE stellar kinematics and stellar populations maps. In particular, we confirm that NGC 3115 has a thin fast-rotating stellar disc embedded in a fast-rotating spheroid, and that these two structures show clear differences in their stellar age and metallicity properties. We emphasise an observed correlation between the radial stellar velocity, V, and the Gauss-Hermite moment, h_3_, which creates a butterfly shape in the central 15" of the h_3_ map. We further detect the previously reported weak spiral- and ring-like structures, and find evidence that these features can be associated with regions of younger mean stellar ages. We provide tentative evidence for the presence of a bar, although the V-h_3_ correlation can be reproduced by a simple axisymmetric dynamical model. Finally, we present a reconstruction of the two-dimensional star formation history of NGC 3115 and find that most of its current stellar mass was formed at early epochs (>12Gyr ago), while star formation continued in the outer (kpc-scale) stellar disc until recently. Since z~2 and within ~4R_e_, we suggest that NGC 3115 has been mainly shaped by secular processes.
1787. NGC 7009 MUSE imaging spectroscopic survey
ID:
ivo://CDS.VizieR/J/A+A/620/A169
Title:
NGC 7009 MUSE imaging spectroscopic survey
Short Name:
J/A+A/620/A169
Date:
21 Oct 2021
Publisher:
CDS
Description:
The spatial structure of the emission lines and continuum over the 50-arcsecond extent of the nearby, O-rich, PN NGC 7009 (Saturn Nebula) have been observed with the MUSE integral field spectrograph on the ESO Very Large Telescope. This study concentrates on maps of line emission and their interpretation in terms of physical conditions. MUSE Science Verification data, in <0.6-arcsecond seeing, have been reduced and analysed as maps of emission lines and continuum over the wavelength range 4750-9350{AA}. The dust extinction, the electron densities and temperatures of various phases of the ionized gas, abundances of species from low to high ionization and some total abundances are determined using standard techniques. Emission line maps over the bright shells are presented, from neutral to the highest ionization available (HeII and [MnV]). For collisionally excited lines (CELs), maps of electron temperature (Te from [NII] and [SIII]) and density (Ne from [SII] and [ClIII]) are available and for optical recombination lines (ORLs) temperature (from the Paschen jump and ratio of HeI lines) and density (from high Paschen lines). These estimates are compared: for the first time, maps of the differences in CEL and ORL Te's have been derived, and correspondingly a map of t^2^ between a CEL and ORL temperature, showing considerable detail. Total abundances of only He and O were formed, the latter using three ionization correction factors. However the map of He/H is not flat, departing by ~2% from a constant value, with remnants corresponding to ionization structures. An integrated spectrum over an area of 2340-arcseconds squared was also formed and compared to 1D photoionization models. The spatial variation of a range of nebular parameters illustrates the complexity of the ionized media in NGC 7009. These MUSE data are very rich with detections of hundreds of lines over areas of hundreds of arcseconds squared and follow-on studies are outlined.
1788. NGC 6240 MUSE observations
ID:
ivo://CDS.VizieR/J/A+A/633/A79
Title:
NGC 6240 MUSE observations
Short Name:
J/A+A/633/A79
Date:
21 Oct 2021
Publisher:
CDS
Description:
NGC 6240 is a well-studied nearby galaxy system in the process of merging. Based on optical, X-ray, and radio observations, it is thought to harbor two active nuclei. We carried out a detailed optical 3D spectroscopic study to investigate the inner region of this system in connection with existing MERLIN and VLBA data. We observed NGC 6240 with very high spatial resolution using the MUSE instrument in the Narrow-Field Mode with the four-laser GALACSI adaptive optics system on the ESO VLT under seeing conditions of 0.49''. Our 3D spectra cover the wavelength range from 4725 to 9350 Angstroem at a spatial resolution of about 75 mas. We report the discovery of three nuclei in the final state of merging within a region of only 1 kpc in the NGC 6240 system. Thanks to MUSE we are able to show that the formerly unresolved southern component actually consists of two distinct nuclei separated by only 198pc. In combination with Gaia data we reach an absolute positional accuracy of only 30mas that is essential to compare optical spectra with MERLIN and VLBA radio positions. The verification and detailed study of a system with three nuclei, two of which are active and each with a mass in excess of 9x10^7^M_{sun}_, is of great importance for the understanding of hierarchical galaxy formation via merging processes since multiple mergers lead to a faster evolution of massive galaxies in comparison to binary mergers. So far it has been suggested that the formation of galactic nuclei with multiple supermassive black holes (SMBHs) is expected to be rare in the local universe. Triple massive black hole systems might be of fundamental importance for the coalescence of massive black hole binaries in less than a Hubble time leading to the loudest sources of gravitational waves in the megahertz regime.
1789. NGC 300 MUSE spectroscopy for central fields
ID:
ivo://CDS.VizieR/J/A+A/618/A3
Title:
NGC 300 MUSE spectroscopy for central fields
Short Name:
J/A+A/618/A3
Date:
21 Oct 2021
Publisher:
CDS
Description:
As a new approach to the study of resolved stellar populations in nearby galaxies, we present a pilot study in NGC300 to demonstrate that integral field spectroscopy with high spatial resolution and excellent seeing conditions reaches an unprecedented depth in severely crowded fields. Observations by MUSE with seven pointings in NGC 300 have resulted in data cubes that are analyzed in four ways: (1) Point spread function-fitting 3D spectroscopy with PampelMUSE, as already successfully pioneered in globular clusters, yields de-blended spectra of individually distinguishable stars, thus providing a complete inventory of blue and red supergiants, and asymptotic giant branch (AGB) stars of type M and C. The technique is also applicable to emission line point sources and provides samples of planetary nebulae (PNe) that are complete down to m_5007_=28. (2) Pseudo-monochromatic images, created at the wavelengths of the most important emission lines and corrected for continuum light with the P3D visualization tool, provide maps of HII regions, supernova remnants (SNR), and the diffuse interstellar medium (ISM) at a high level of sensitivity, where also faint point sources stand out and allow for the discovery of PNe, Wolf-Rayet (WR) stars, etc. (3) The use of the P3D line-fitting tool yields emission line fluxes, surface brightness, and kinematic information for gaseous objects, corrected for absorption line profiles of the underlying stellar population in the case of H{alpha}. (4) Visual inspection of the data cubes by browsing through the row-stacked spectra image in P3D is demonstrated to be efficient for data mining and the discovery of background galaxies and unusual objects. We present a catalog of luminous stars, rare stars such as WR, and other emission line stars, carbon stars, symbiotic star candidates, PNe, HII regions, SNR, giant shells, peculiar diffuse and filamentary emission line objects, and background galaxies, along with their spectra. The technique of crowded-field 3D spectroscopy, using the PampelMUSE code, is capable of deblending individual bright stars, the unresolved background of faint stars, gaseous nebulae, and the diffuse component of the ISM, resulting in unprecedented legacy value for observations of nearby galaxies with MUSE.
1790. NGC 6334-NGC 6357 complex
ID:
ivo://CDS.VizieR/J/A+A/515/A55
Title:
NGC 6334-NGC 6357 complex
Short Name:
J/A+A/515/A55
Date:
21 Oct 2021
Publisher:
CDS
Description:
Our knowledge of high-mass star formation has been mainly based on follow-up studies of bright sources found by IRAS, and has thus been incomplete for its earliest phases, which are inconspicuous at infrared wavelengths. With a new generation of powerful bolometer arrays, unbiased large-scale surveys of nearby high-mass star-forming complexes now search for the high-mass analog of low-mass cores and class 0 protostars. Following the pioneering study of Cygnus X, we investigate the star-forming region NGC 6334-NGC 6357 (~1.7kpc)

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