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1171. NGC 2808 stellar population spectra
ID:
ivo://CDS.VizieR/J/A+A/631/A14
Title:
NGC 2808 stellar population spectra
Short Name:
J/A+A/631/A14
Date:
21 Oct 2021
Publisher:
CDS
Description:
Galactic globular clusters (GCs) are now known to host multiple populations displaying particular abundance variations. The different populations within a GC can be well distinguished following their position in the pseudo two-colors diagrams, also referred to as "chromosome maps". These maps are constructed using optical and near-UV photometry available from the Hubble Space Telescope (HST) UV survey of GCs. However, the chemical tagging of the various populations in the chromosome maps is hampered by the fact that HST photometry and elemental abundances are both available only for a limited number of stars. The spectra collected as part of the MUSE survey of globular clusters provide a spectroscopic counterpart to the HST photometric catalogs covering the central regions of GCs. In this paper, we use the MUSE spectra of 1155 red giant branch (RGB) stars in NGC 2808 to characterize the abundance variations seen in the multiple populations of this cluster. We use the chromosome map of NGC 2808 to divide the RGB stars into their respective populations. We then combine the spectra of all stars belonging to a given population, resulting in one high signal-to-noise ratio spectrum representative of each population. Variations in the spectral lines of O, Na, Mg, and Al are clearly detected among four of the populations. In order to quantify these variations, we measured equivalent width differences and created synthetic populations spectra that were used to determine abundance variations with respect to the primordial population of the cluster. Our results are in good agreement with the values expected from previous studies based on high-resolution spectroscopy. We do not see any significant variations in the spectral lines of Ca, K, and Ba. We also do not detect abundance variations among the stars belonging to the primordial population of NGC 2808.
1172. NGC2264 structure and star formation history
ID:
ivo://CDS.VizieR/J/A+A/609/A10
Title:
NGC2264 structure and star formation history
Short Name:
J/A+A/609/A10
Date:
21 Oct 2021
Publisher:
CDS
Description:
Reconstructing the structure and history of young clusters is pivotal to understanding the mechanisms and timescales of early stellar evolution and planet formation. Recent studies suggest that star clusters often exhibit a hierarchical structure, possibly resulting from several star formation episodes occurring sequentially rather than a monolithic cloud collapse. We aim to explore the structure of the open cluster and star-forming region NGC 2264 (~3Myr), which is one of the youngest, richest and most accessible star clusters in the local spiral arm of our Galaxy; we link the spatial distribution of cluster members to other stellar properties such as age and evolutionary stage to probe the star formation history within the region. We combined spectroscopic data obtained as part of the Gaia-ESO Survey (GES) with multi-wavelength photometric data from the Coordinated Synoptic Investigation of NGC 2264 (CSI 2264) campaign. We examined a sample of 655 cluster members, with masses between 0.2 and 1.8M_{sun}_ and including both disk-bearing and disk-free young stars. We used Teff estimates from GES and g,r,i photometry from CSI 2264 to derive individual extinction and stellar parameters.
1173. NGC 5427 WiFeS data cubes
ID:
ivo://CDS.VizieR/J/A+A/566/A41
Title:
NGC 5427 WiFeS data cubes
Short Name:
J/A+A/566/A41
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have observed the nearby, nearly face-on, Seyfert 2 galaxy, NGC 5427, using optical integral field spectroscopy of both the nuclear regions and the HII regions in the spiral arms. The observed spectra have been modelled using the MAPPINGS IV photoionisation code, both to derive the chemical abundances in the HII regions and the Seyfert nucleus, and to constrain the EUV spectral energy distribution of the AGN illuminating the extended narrow-line region.
1174. NGVS VI. Ultra-compact dwarfs in M87
ID:
ivo://CDS.VizieR/J/ApJ/802/30
Title:
NGVS VI. Ultra-compact dwarfs in M87
Short Name:
J/ApJ/802/30
Date:
21 Oct 2021
Publisher:
CDS
Description:
The origin of ultra-compact dwarfs (UCDs; r_h_>~10pc) --objects larger and more massive than typical globular clusters (GCs), but more compact than typical dwarf galaxies-- has been hotly debated in the 15yrs since their discovery. Even whether UCDs should be considered galactic in origin, or simply the most extreme star clusters, is not yet settled. We present the dynamical properties of 97 spectroscopically confirmed UCDs and 911 GCs associated with the central cD galaxy of the Virgo cluster, M87. Our UCDs, of which 89% have M_*_>~2x10^6^M_{sun}_ and 92% are as blue as the classic blue GCs, nearly triple the confirmed sample of Virgo UCDs, providing by far the best opportunity for studying global dynamics of a UCD system. We found that (1) UCDs have a surface number density profile that is shallower than that of blue GCs in the inner ~70kpc and as steep as that of red GCs at larger radii; (2) UCDs exhibit a significantly stronger rotation than GCs, and blue GCs seem to have a velocity field that is more consistent with that of the surrounding dwarf ellipticals than with that of UCDs; (3) UCDs have an orbital anisotropy profile that is tangentially biased at radii <~40kpc and radially biased farther out, whereas blue GCs become more tangentially biased at larger radii beyond ~40kpc; (4) GCs with M_*_>~2x10^6^M_{sun}_ have rotational properties indistinguishable from the less massive ones, suggesting that it is the size, instead of mass, that differentiates UCDs from GCs as kinematically distinct populations. We conclude that most UCDs in M87 are not consistent with being merely the most luminous and extended examples of otherwise normal GCs. The radially biased orbital structure of UCDs at large radii is in general agreement with the "tidally threshed dwarf galaxy" scenario.
1175. NH3 line profiles in star-forming regions
ID:
ivo://CDS.VizieR/J/ApJ/806/74
Title:
NH3 line profiles in star-forming regions
Short Name:
J/ApJ/806/74
Date:
21 Oct 2021
Publisher:
CDS
Description:
Anomalous ammonia (NH_3_) spectra, exhibiting asymmetric hyperfine satellite intensity profiles in the (J,K)=(1,1) inversion transition, have been observed in star-forming regions for over 35 years. We present a systematic study of this "hyperfine intensity anomaly" (HIA) toward a sample of 334 high-mass star forming regions: 310 high-mass (>~100M_{sun}_) clumps and 24 infrared dark clouds. The HIA is ubiquitous in high-mass star forming regions. Although LTE excitation predicts that the intensity ratios of the outer satellites and inner satellites are exactly unity, for this sample the ensemble average ratios are 0.812+/-0.004 and 1.125+/-0.005, respectively. We have quantified the HIA and find no significant relationships between the HIA and temperature, line width, optical depth, and the stage of stellar evolution. The fact that HIAs are common in high-mass star-forming regions suggests that the conditions that lead to HIAs are ubiquitous in these regions. A possible link between HIAs and the predictions of the competitive accretion model of high-mass star formation is suggested; however, the expected trends of HIA strength with clump evolutionary stage, rotational temperature, and line width for evolving cores in competitive accretion models are not found. Thus, the exact gas structures that produce HIAs remain unknown. Turbulent gas structures are a possible explanation, but the details need to be explored.
1176. NIBLES II. Arecibo follow-up observations
ID:
ivo://CDS.VizieR/J/A+A/596/A60
Title:
NIBLES II. Arecibo follow-up observations
Short Name:
J/A+A/596/A60
Date:
21 Oct 2021
Publisher:
CDS
Description:
We obtained Arecibo HI line follow-up observations of 154 of the 2600 galaxies in the Nancay Interstellar Baryons Legacy Extragalactic Survey (NIBLES) sample. These observations are on average four times more sensitive than the original observations at the Nancay Radio Telescope. The main goal of this survey is to characterize the underlying HI properties of the NIBLES galaxies which were undetected or marginally detected at Nancay. Of the Nancay non-detections, 85% were either clearly or marginally detected at Arecibo, while 89% of the Nancay marginal detections were clearly detected. Based on the statistics of the detections relative to g-i color and r-band luminosity (Lr) distribution among our Arecibo observations, we anticipate ~60% of our 867 Nancay non-detections and marginal detections could be detected at the sensitivity of our Arecibo observations. Follow-up observations of our low luminosity (Lr<10^8.5^L_{sun}_) blue sources indicate that they have, on average, more concentrated stellar mass distributions than the Nancay detections in the same luminosity range, suggesting we may be probing galaxies with intrinsically different properties. These follow-up observations enable us to probe HI mass fractions, log(MHI/M*) 0.5dex and 1dex lower, on average, than the NIBLES and ALFALFA surveys respectively.
1177. [NII] observations of the Carina Nebula (NGC 3372)
ID:
ivo://CDS.VizieR/J/ApJ/739/100
Title:
[NII] observations of the Carina Nebula (NGC 3372)
Short Name:
J/ApJ/739/100
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results of a ~250arcmin^2^ mapping of the 205um [NII] fine-structure emission over the northern Carina Nebula, including the Car I and Car II HII regions. Spectra were obtained using the South Pole Imaging Fabry-Perot Interferometer (SPIFI) at the Antarctic Submillimeter Telescope and Remote Observatory (AST/RO) at the South Pole. We supplement the 205um data with new reductions of far-IR fine-structure spectra from the Infrared Space Observatory (ISO) Long Wavelength Spectrometer (LWS) in 63um [OI], 122um [NII], 146um [OI], and 158um [CII]; the 146um [OI] data include 90 raster positions which have not been previously published. Morphological comparisons are made with optical, radio continuum, and CO maps. The 122/205 line ratio is used to probe the density of the low-ionization gas, and the 158/205 line ratio is used to probe the fraction of C^+^ arising from photodissociation regions (PDRs). The [OI] and [CII] lines are used to construct a PDR model of Carina. When the PDR properties are compared with other sources, Carina is found to be more akin to 30 Doradus than galactic star-forming regions such as Orion, M17, or W49; this is consistent with the view of Carina as a more evolved region, where much of the parent molecular cloud has been ionized or swept away. These data constitute the first ground-based detection of the 205um [NII] line, and the third detection overall since those of COBE FIRAS and the Kuiper Airborne Observatory in the early 1990s.
1178. [NII]205um emission in local luminous IR galaxies
ID:
ivo://CDS.VizieR/J/ApJ/819/69
Title:
[NII]205um emission in local luminous IR galaxies
Short Name:
J/ApJ/819/69
Date:
21 Oct 2021
Publisher:
CDS
Description:
In this paper, we present the measurements of the [NII]205{mu}m line for a flux-limited sample of 122 (ultra-)luminous infrared galaxies [(U)LIRGs] and 20 additional normal galaxies, obtained with the Herschel Space Observatory (Herschel). We explore the far-infrared (FIR) color dependence of the [NII]205{mu}m (L_[NII]205{mu}m_) to the total infrared (L_IR_) luminosity ratio, and find that L_[NII]205{mu}m_/L_IR_ only depends modestly on the 70-160{mu}m flux density ratio (f70/f160) when f70/f160<~0.6, whereas such dependence becomes much steeper for f70/f160>0.6. We also investigate the relation between L_[NII]205{mu}m_ and star formation rate (SFR), and show that L_[NII]205{mu}m_ has a nearly linear correlation with SFR, albeit the intercept of such a relation varies somewhat with f60/f100, consistent with our previous conclusion that [NII]205{mu}m emission can serve as an SFR indicator with an accuracy of ~0.4dex, or ~0.2dex if f60/f100 is known independently. Furthermore, together with the Infrared Space Observatory measurements of [NII], we use a total of ~200 galaxies to derive the local [NII]205{mu}m luminosity function (LF) by tying it to the known IR LF with a bivariate method. As a practical application, we also compute the local SFR volume density ({rho}_SFR_) using the newly derived SFR calibrator and LF. The resulting log{rho}_SFR_=-1.96+/-0.11M_{sun}_/yr/Mpc^3^ agrees well with previous studies. Finally, we determine the electron densities (n_e_) of the ionized medium for a subsample of 12 (U)LIRGs with both [NII]205{mu}m and [NII]122{mu}m data, and find that n_e_ is in the range of ~1-100/cm^3^, with a median value of 22/cm^3^.
1179. NIR H lines in TTS
ID:
ivo://CDS.VizieR/J/A+A/365/90
Title:
NIR H lines in TTS
Short Name:
J/A+A/365/90
Date:
21 Oct 2021
Publisher:
CDS
Description:
Paschen {beta} and/or Bracket {gamma} emission line profiles were obtained for a sample of 50 T Tauri stars mostly from the Taurus-Auriga complex. The tables presented here contain the computed line parameters of the observed line profiles.
1180. NIR knots in the Cas A supernova remnant
ID:
ivo://CDS.VizieR/J/ApJ/837/118
Title:
NIR knots in the Cas A supernova remnant
Short Name:
J/ApJ/837/118
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report the results of broadband (0.95-2.46{mu}m) near-infrared spectroscopic observations of the Cassiopeia A supernova remnant. Using a clump-finding algorithm in two-dimensional dispersed images, we identify 63 "knots" from eight slit positions and derive their spectroscopic properties. All of the knots emit [FeII] lines together with other ionic forbidden lines of heavy elements, and some of them also emit H and He lines. We identify 46 emission line features in total from the 63 knots and measure their fluxes and radial velocities. The results of our analyses of the emission line features based on principal component analysis show that the knots can be classified into three groups: (1) He-rich, (2) S-rich, and (3) Fe-rich knots. The He-rich knots have relatively small, <~200km/s, line-of-sight speeds and radiate strong He I and [FeII] lines resembling closely optical quasi-stationary flocculi of circumstellar medium, while the S-rich knots show strong lines from O-burning material with large radial velocities up to ~2000km/s indicating that they are supernova ejecta material known as fast-moving knots. The Fe-rich knots also have large radial velocities but show no lines from O-burning material. We discuss the origin of the Fe-rich knots and conclude that they are most likely "pure" Fe ejecta synthesized in the innermost region during the supernova explosion. The comparison of [FeII] images with other waveband images shows that these dense Fe ejecta are mainly distributed along the southwestern shell just outside the unshocked ^44^Ti in the interior, supporting the presence of unshocked Fe associated with ^44^Ti.