- ID:
- ivo://CDS.VizieR/J/A+A/649/A178
- Title:
- NGC6791 V604 Lyr disentangled component spectra
- Short Name:
- J/A+A/649/A178
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- Models of stellar structure and evolution can be constrained using accurate measurements of the parameters of eclipsing binary members of open clusters. Multiple binary stars provide the means to tighten the constraints, and in turn, to improve the precision and accuracy of the age estimate of the host cluster. In the previous two papers of this series, we demonstrated the use of measurements of multiple eclipsing binaries in the old open cluster NGC6791 to set tighter constraints on the properties of stellar models than was previously possible, thereby improving both the accuracy and precision of the cluster age. We identify and measure the properties of a non-eclipsing cluster member, V56 (Cl* NGC 6791 KR V56), in NGC 6791 and demonstrate how this provides additional model constraints that support and strengthen our previous findings. We analyse multi-epoch spectra of V56 from FLAMES in conjunction with the existing photometry and measurements of eclipsing binaries in NGC6971. The parameters of the V56 components are found to be Mp=1.103+/-0.008M_{sun}_ and Ms=0.974+/-0.007M_{sun}_, Rp=1.764+/-0.099R_{sun}_ and Rs=1.045+/-0.057R_{sun}_, Teff,p=5447+/-125K and Teff,s=5552+/-125K, and surface [Fe/H]=+0.29+/-0.06 assuming that they have the same abundance. The derived properties strengthen our previous best estimate of the cluster age of 8.3+/-0.3Gyr and the mass of stars on the lower RGB, M_RGB_=1.15+/-0.02M_{sun}_ for NGC 6791. These numbers therefore continue to serve as verification points for other methods of age and mass measures, such as asteroseismology.
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Search Results
- 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.
1763. NGC 7469 X-ray spectra
- ID:
- ivo://CDS.VizieR/J/A+A/615/A72
- Title:
- NGC 7469 X-ray spectra
- Short Name:
- J/A+A/615/A72
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the physical structure of the active galactic nucleus (AGN) wind in the Seyfert-1 galaxy NGC 7469 through high-resolution X-ray spectroscopy with Chandra HETGS and photoionisation modelling. Contemporaneous data from Chandra, HST, and Swift are used to model the optical-UV-X-ray continuum and determine the spectral energy distribution (SED) at two epochs, 13yr apart. For our investigation we use new observations taken in December 2015-January 2016, and historical ones taken in December 2002. We study the impact of a change in the SED shape, seen between the two epochs, on the photoionisation of the wind. The HETGS spectroscopy shows that the AGN wind in NGC 7469 consists of four ionisation components, with their outflow velocities ranging from -400 to -1800km/s. From our modelling we find that the change in the ionising continuum shape between the two epochs results in some variation in the ionisation state of the wind components. However, for the main ions detected in X-rays, the sum of their column densities over all components remains in practice unchanged. For two of the four components, which are found to be thermally unstable in both epochs, we obtain 2<r<31pc and 12<r<29pc using the cooling and recombination timescales. For the other two thermally stable components, we obtain r<31pc and r<80pc from the recombination timescale. The results of our photoionisation modelling and thermal stability analysis suggest that the absorber components in NGC 7469 are consistent with being a thermally driven wind from the AGN torus. Finally, from analysis of the zeroth-order ACIS/HETG data, we discover that the X-ray emission in the range 0.2-1keV is spatially extended over 1.5-12". This diffuse soft X-ray emission is explained by coronal emission from the nuclear starburst ring in NGC 7469. The star formation rate inferred from this diffuse soft X-ray emission is consistent with those found by far-infrared studies of NGC 7469.
- ID:
- ivo://CDS.VizieR/J/ApJS/225/29
- Title:
- NGC 5548 43 year-long monitoring in H{beta}
- Short Name:
- J/ApJS/225/29
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an analysis of 43 years (1972 to 2015) of spectroscopic observations of the Seyfert 1 galaxy NGC 5548. This includes 12 years of new unpublished observations (2003 to 2015). We compiled about 1600 H{beta} spectra and analyzed the long-term spectral variations of the 5100 A continuum and the H{beta} line. Our analysis is based on standard procedures, including the Lomb-Scargle method, which is known to be rather limited to such heterogeneous data sets, and a new method developed specifically for this project that is more robust and reveals a ~5700 day periodicity in the continuum light curve, the H{beta} light curve, and the radial velocity curve of the red wing of the H{beta} line. The data are consistent with orbital motion inside the broad emission line region of the source. We discuss several possible mechanisms that can explain this periodicity, including orbiting dusty and dust-free clouds, a binary black hole system, tidal disruption events, and the effect of an orbiting star periodically passing through an accretion disk.
- 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.
- ID:
- ivo://CDS.VizieR/J/ApJ/735/111
- Title:
- NH_3_ line lists at high temperatures
- Short Name:
- J/ApJ/735/111
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present line lists for ammonia (NH_3_) at high temperatures obtained by recording Fourier transform infrared emission spectra. Calibrated line lists are presented for 12 temperatures (300{deg}C-1300{deg}C in 100{deg}C intervals and 1370{deg}C) and each line list covers the 740-2100cm^-1^ range, which includes the majority of the {nu}_2_ umbrella bending mode region (11um) and the {nu}_4_ asymmetric bending mode region (6.2um). We also demonstrate the useful technique of obtaining empirical lower state energies from a set of spectra recorded at different sample temperatures. Using our NH_3_ spectra, we have estimated lower state energies (E_Low_ in cm^-1^) and our values have been incorporated into the line lists along with calibrated wavenumbers (\tilde{nu} in cm^-1^) and calibrated line intensities (S' in cm/molecule) for each line. We expect our hot NH_3_ line lists to find direct application in the modeling of planetary atmospheres and brown dwarfs.
- 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.
- 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.
- ID:
- ivo://CDS.VizieR/J/ApJ/827/74
- Title:
- [NII]/H{alpha} ratio in galaxies with KMOS^3D^
- Short Name:
- J/ApJ/827/74
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present measurements of the [NII]/H{alpha} ratio as a probe of gas-phase oxygen abundance for a sample of 419 star-forming galaxies at z=0.6-2.7 from the KMOS^3D^ near-IR multi-integral field unit (IFU) survey. The mass-metallicity relation (MZR) is determined consistently with the same sample selection, metallicity tracer, and methodology over the wide redshift range probed by the survey. We find good agreement with long-slit surveys in the literature, except for the low-mass slope of the relation at z~2.3, where this sample is less biased than previous samples based on optical spectroscopic redshifts. In this regime we measure a steeper slope than some literature results. Excluding the contribution from active galactic nuclei from the MZR reduces sensitivity at the high-mass end, but produces otherwise consistent results. There is no significant dependence of the [NII]/H{alpha} ratio on star formation rate at fixed redshift and stellar mass. The IFU data allow spatially resolved measurements of [NII]/H{alpha}, from which we can infer abundance gradients for 180 galaxies, thus tripling the current sample in the literature. The observed gradients are on average flat, with only 15 gradients statistically offset from zero at >3{sigma}. We have modeled the effect of beam smearing, assuming a smooth intrinsic radial gradient and known seeing, inclination, and effective radius for each galaxy. Our seeing-limited observations can recover up to 70% of the intrinsic gradient for the largest, face-on disks, but only 30% for the smaller, more inclined galaxies. We do not find significant trends between observed or corrected gradients and any stellar population, dynamical, or structural galaxy parameters, mostly in agreement with existing studies with much smaller sample sizes. In cosmological simulations, strong feedback is generally required to produce flat gradients at high redshift.
- 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.
