- ID:
- ivo://CDS.VizieR/J/A+A/556/A26
- Title:
- Arches cluster: IR phot., extinction and masses
- Short Name:
- J/A+A/556/A26
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Galactic Center is the most active site of star formation in the Milky Way Galaxy, where particularly high-mass stars have formed very recently and are still forming today. However, since we are looking at the Galactic Center through the Galactic disk, knowledge of extinction is crucial to study this region. The Arches cluster is a young, massive starburst cluster near the Galactic Center. We observed the Arches cluster out to its tidal radius using Ks-band imaging obtained with NAOS/CONICA at the VLT combined with Subaro/Cisco J-band data to gain a full understanding of the cluster mass distribution. We show that the determination of the mass of the most massive star in the Arches cluster, which had been used in previous studies to establish an upper-mass limit for the star formation process in the Milky Way, strongly depends on the assumed slope of the extinction law. Assuming the two regimes of widely used infrared extinction laws, we show that the difference can reach up to 30% for individually derived stellar masses and {Delta}AKs~1 magnitude in acquired Ks-band extinction, while the present mass function slope changes by ~0.17dex. The present-day mass function slope derived assuming the Nishiyama et al. (2009) extinction law increases from a flat slope of {alpha}-Nishi=-1.50+/-0.35 in the core (r<0.2pc) to {alpha}-Nishi=-2.21+/-0.27 in the intermediate annulus (0.2<r<0.4pc), where the Salpeter slope is -2.3. The present-day mass function steepens to {alpha}-Nishi=-3.21+/-0.30 in the outer annulus (0.4<r<1.5pc), indicating that the outer cluster region is depleted of high mass stars. This picture is consistent with mass segregation due to the dynamical evolution of the cluster.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/647/A110
- Title:
- Arches cluster JVLA 6 and 10GHz images
- Short Name:
- J/A+A/647/A110
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present high angular resolution radio observations of the Arches cluster in the Galactic centre, one of the most massive young clusters in the Milky Way. The data were acquired in two epochs and at 6 and 10 GHz with the Karl G. Jansky Very Large Array (JVLA). The rms noise reached is 3-4 times better than previous observations and we have almost doubled the number of known radio stars in the cluster. Nine of them have spectral indices consistent with thermal emission from ionised stellar winds. One is a confirmed wind colliding binary and two sources are ambiguous cases. Regarding variability, the radio emission appears to be stable on time scales of a few to ten years. Finally, we have showed that the number of radio stars can be used as a tool for constraining the age or mass of a cluster and also its mass function.
- ID:
- ivo://CDS.VizieR/J/MNRAS/410/1837
- Title:
- Architecture of A1386 and the Sloan Great Wall
- Short Name:
- J/MNRAS/410/1837
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new radial velocities from AAOmega on the Anglo-Australian Telescope for 307 galaxies (bJ < 19.5) in the region of the rich cluster Abell 1386. Consistent with other studies of galaxy clusters that constitute subunits of superstructures, we find that the velocity distribution of A1386 is very broad (21000-42000 km/s, or z = 0.08-0.14) and complex. The mean redshift of the cluster that Abell designated as number 1386 is found to be ~0.104. However, we find that it consists of various superpositions of line-of-sight components. We investigate the reality of each component by testing for substructure and searching for giant elliptical galaxies in each and show that A1386 is made up of at least four significant clusters or groups along the line of sight whose global parameters we detail. Peculiar velocities of brightest galaxies for each of the groups are computed and found to be different from previous works, largely due to the complexity of the sky area and the depth of analysis performed in the present work. We also analyse A1386 in the context of its parent superclusters: Leo A and especially the Sloan Great Wall. Although the new clusters may be moving towards mass concentrations in the Sloan Great Wall or beyond, many are most likely not yet physically bound to it.
- ID:
- ivo://CDS.VizieR/J/ApJ/898/119
- Title:
- Archival Keck HIRES spectra analyzed with The Cannon
- Short Name:
- J/ApJ/898/119
- Date:
- 15 Dec 2021 00:08:08
- Publisher:
- CDS
- Description:
- To accurately interpret the observed properties of exoplanets, it is necessary to first obtain a detailed understanding of host star properties. However, physical models that analyze stellar properties on a per-star basis can become computationally intractable for sufficiently large samples. Furthermore, these models are limited by the wavelength coverage of available spectra. We combine previously derived spectral properties from the Spectroscopic Properties of Cool Stars (SPOCS) catalog with generative modeling using The Cannon to produce a model capable of deriving stellar parameters (logg, Teff, and vsini) and 15 elemental abundances (C, N, O, Na, Mg, Al, Si, Ca, Ti, V, Cr, Mn, Fe, Ni, and Y) for stellar spectra observed with Keck Observatory's High Resolution Echelle Spectrometer (HIRES). We demonstrate the high accuracy and precision of our model, which takes just ~3s to classify each star, through cross-validation with pre-labeled spectra from the SPOCS sample. Our trained model, which takes continuum-normalized template spectra as its inputs, is publicly available at http://github.com/malenarice/keckspec. Finally, we interpolate our spectra and employ the same modeling scheme to recover labels for 477 stars using archival stellar spectra obtained prior to Keck's 2004 detector upgrade, demonstrating that our interpolated model can successfully predict stellar labels for different spectrographs that have (1) sufficiently similar systematics and (2) a wavelength range that substantially overlaps with that of the post-2004 HIRES spectra.
- ID:
- ivo://fai.kz/spectra_agn_archive/q/ssa
- Title:
- Archive of AGN spectral observations
- Short Name:
- AGN Arch. SSAP
- Date:
- 09 Dec 2024 11:20:09
- Publisher:
- Fesenkov Astrophysical Institute
- Description:
- The archive of AGN spectral observations is obtained on AZT-8 telescope at the Fesenkov Astrophysical Institute (FAI), Almaty, Kazakhstan. It represents the result of observations for abot 25 years - from 1970 to 1995. All observations were carried out at AZT-8 (D = 700 mm, F[main] = 2800 mm, F[Cassegrain] = 11000 mm) with a high-power spectrograph. In 1967-68, on the basis of the image intensifier (https://doi.org/10.1080/1055679031000084795a) developed and assembled the spectrograph of the original design in the workshops of the FAI.
- ID:
- ivo://nasa.heasarc/acceptcat
- Title:
- Archive of Chandra Cluster Entropy Profile Tables (ACCEPT) Catalog
- Short Name:
- ACCEPTCAT
- Date:
- 14 Feb 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table, the Archive of Chandra Cluster Entropy Profile Tables (ACCEPT) Catalog, contains the radial entropy profiles of the intracluster medium (ICM) for a collection of 239 clusters taken from the Chandra X-ray Observatory's Data Archive. Entropy is of great interest because it controls ICM global properties and records the thermal history of a cluster. The authors find that most ICM entropy profiles are well fitted by a model which is a power law at large radii and approaches a constant value at small radii: K(r) = K<sub>0</sub> + K<sub>100</sub> (r/100 kpc)<sup>alpha</sup>, where K<sub>0</sub> quantifies the typical excess of core entropy above the best-fitting power law found at larger radii. The authors also show that the K<sub>0</sub> distributions of both the full archival sample and the primary Highest X-Ray Flux Galaxy Cluster Sample of Reiprich (2001, Ph.D. thesis) are bimodal with a distinct gap between K<sub>0</sub> ~ 30 - 50 keV cm<sup>2</sup> and population peaks at K<sub>0</sub> ~ 15 keV cm<sup>2</sup> and K<sub>0</sub> ~ 150 keV cm<sup>2</sup>. The effects of point-spread function smearing and angular resolution on best-fit K<sub>0</sub> values are investigated using mock Chandra observations and degraded entropy profiles, respectively. The authors find that neither of these effects is sufficient to explain the entropy-profile flattening they measure at small radii. The influence of profile curvature and the number of radial bins on the best-fit K<sub>0</sub> is also considered, and they find no indication that K<sub>0</sub> is significantly impacted by either. All data and results associated with this work are publicly available via the project web site <a href="http://www.pa.msu.edu/astro/MC2/accept/">http://www.pa.msu.edu/astro/MC2/accept/</a>. The sample is collected from observations taken with the Chandra X-ray Observatory and which were publicly available in the CDA (Chandra Data Archive) as of 2008 August. This table was created by the HEASARC in January 2012 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJS/182/12">CDS Catalog J/ApJS/182/12</a> files table1.dat and table5.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://CDS.VizieR/J/ApJS/125/409
- Title:
- Arcsecond positions of UGC galaxies
- Short Name:
- J/ApJS/125/409
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present accurate B1950 and J2000 positions for all confirmed galaxies in the Uppsala General Catalog (UGC, Cat. <VII/26>). The positions were measured visually from Digitized Sky Survey images with rms uncertainties {sigma}<=[(1.2")^2^+({theta}/100)^2^]^1/2^, where is the major-axis diameter. We compared each galaxy measured with the original UGC description to ensure high reliability. The full position list is available in the electronic version only. the major-axis diameter. We compared each galaxy measured with the original UGC description to ensure high reliability. The full position list is available in the electronic version only.
1138. Arcturus Lab (line list)
- ID:
- ivo://CDS.VizieR/J/A+A/645/A19
- Title:
- Arcturus Lab (line list)
- Short Name:
- J/A+A/645/A19
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- High-resolution spectroscopy in the near infrared (NIR) is a powerful tool to characterise the physical and chemical properties of cool star atmospheres. The current generation of NIR echelle spectrographs enables the sampling of many spectral features over the full 0.9-2.4um range for a detailed chemical tagging. Within the Stellar Population Astrophysics Large Program at the TNG, we used a high-resolution (R=50000) NIR spectrum of Arcturus acquired with the GIANO-B echelle spectrograph as a laboratory to define and calibrate an optimal line list and new diagnostic tools to derive accurate stellar parameters and chemical abundances. We inspected several hundreds of NIR atomic and molecular lines to derive abundances of 26 different chemical species, including CNO, iron-group, alpha, Z-odd and neutron-capture elements. We then performed a similar analysis in the optical using Arcturus VLT-UVES spectra. By the combined NIR and optical analysis we defined a new thermometer and a new gravitometer for giant stars, based on the comparison of Carbon and Oxygen abundances, respectively, as derived from atomic and molecular lines. We then derived self-consistent stellar parameters and chemical abundances of Arcturus over the full 4800-24500{AA} spectral range and we compared them with previous studies in the literature. We finally discussed a number of problematic lines, which can be affected by deviations from thermal equilibrium and/or chromospheric activity, as traced by the observed variability of HeI at 10830{AA}.
- ID:
- ivo://CDS.VizieR/J/AJ/131/1184
- Title:
- A recalibration of optical photometry
- Short Name:
- J/AJ/131/1184
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- I use high-quality Hubble Space Telescope (HST) spectrophotometry to analyze the calibration of three popular optical photometry systems: Tycho-2 B_T_ and V_T_, Stromgren uvby, and Johnson UBV.
- ID:
- ivo://CDS.VizieR/J/ApJ/880/141
- Title:
- Arecibo 21cm obs. of sources in 5 GMC regions
- Short Name:
- J/ApJ/880/141
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report Arecibo 21cm absorption-emission observations to characterize the physical properties of neutral hydrogen (HI) in the proximity of five giant molecular clouds (GMCs): Taurus, California, Rosette, Mon OB1, and NGC 2264. Strong HI absorption was detected toward all 79 background-continuum sources in the ~60x20 square degree region. Gaussian decompositions were performed to estimate temperatures, optical depths, and column densities of the cold and warm neutral medium (CNM and WNM). The properties of individual CNM components are similar to those previously observed along random Galactic sightlines and in the vicinity of molecular clouds, suggesting a universality of cold HI properties. The CNM spin temperature (Ts) histogram peaks at ~50K. The turbulent Mach numbers of CNM components vary widely, with a typical value of ~4, indicating that their motions are supersonic. About 60% of the total HI gas is WNM, and nearly 40% of the WNM lies in thermally unstable regime 500-5000K. The observed CNM fraction is higher around GMCs than in diffuse regions, and increases with increasing column density (N_HI_) to a maximum of ~75%. On average, the optically thin approximation (N_HI_^*^) underestimates the total column density by ~21%, but we find large regional differences in the relationship between N_HI_ and the required correction factor, f=N_HI_/N_HI_^*^. We examine two different methods (linear fit of f versus log_10_(N_HI_^*^) and uniform Ts) to correct for opacity effects using emission data from the GALFA-HI survey. We prefer the uniform Ts method because the linear relationship does not produce convincing fits for all subregions.
