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1631. Mid-J CO shock tracing observations of IRDCs II
ID:
ivo://CDS.VizieR/J/A+A/587/A96
Title:
Mid-J CO shock tracing observations of IRDCs II
Short Name:
J/A+A/587/A96
Date:
21 Oct 2021
Publisher:
CDS
Description:
Infrared dark clouds are kinematically complex molecular structures in the interstellar medium that can host sites of massive star formation. We present maps measuring 4 square arcminutes of the ^12^CO, ^13^CO, and C^18^O J=3 to 2 lines from selected locations within the C and F (G028.37+00.07 and G034.43+00.24) infrared dark clouds (IRDCs), as well as single pointing observations of the ^13^CO and C^18^O J=2 to 1 lines towards three cores within these clouds. We derive CO gas temperatures throughout the maps and find that CO is significantly frozen out within these IRDCs. We find that the CO depletion tends to be the highest near column density peaks with maximum depletion factors between 5 and 9 in IRDC F and between 16 and 31 in IRDC C. We also detect multiple velocity components and complex kinematic structure in both IRDCs. Therefore, the kinematics of IRDCs seem to point to dynamically evolving structures yielding dense cores with considerable depletion factors.
1632. MIKE obs. of 2 metal-poor stars in Sylgr stream
ID:
ivo://CDS.VizieR/J/ApJ/883/84
Title:
MIKE obs. of 2 metal-poor stars in Sylgr stream
Short Name:
J/ApJ/883/84
Date:
21 Oct 2021
Publisher:
CDS
Description:
We observe two metal-poor main-sequence stars that are members of the recently discovered Sylgr stellar stream. We present radial velocities, stellar parameters, and abundances for 13 elements derived from high-resolution optical spectra collected using the Magellan Inamori Kyocera Echelle spectrograph. The two stars have identical compositions (within 0.13 dex or 1.2{sigma}) among all elements detected. Both stars are very metal-poor ([Fe/H]=-2.92+/-0.06). Neither star is highly enhanced in C ([C/Fe]<+1.0). Both stars are enhanced in the {alpha} elements Mg, Si, and Ca ([{alpha}/Fe]=+0.32+/-0.06), and the ratios among Na, Al, and all Fe-group elements are typical for other stars in the halo and ultra-faint and dwarf spheroidal galaxies at this metallicity. Sr is mildly enhanced ([Sr/Fe]=+0.22+/-0.11), but Ba is not enhanced ([Ba/Fe]{<}-0.4), indicating that these stars do not contain high levels of neutron-capture elements. The Li abundances match those found in metal-poor unevolved field stars and globular clusters (GCs) (log{epsilon}(Li)=2.05+/-0.07), which implies that environment is not a dominant factor in determining the Li content of metal-poor stars. The chemical compositions of these two stars cannot distinguish whether the progenitor of the Sylgr stream was a dwarf galaxy or a GC. If the progenitor was a dwarf galaxy, the stream may originate from a dense region such as a nuclear star cluster. If the progenitor was a GC, it would be the most metal-poor GC known.
1633. MILES base models & new line index system
ID:
ivo://CDS.VizieR/J/MNRAS/404/1639
Title:
MILES base models & new line index system
Short Name:
J/MNRAS/404/1639
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present synthetic spectral energy distributions (SEDs) for single-age, single-metallicity stellar populations (SSPs) covering the full optical spectral range at moderately high resolution [full width at half-maximum (FWHM)=2.3{AA}]. These SEDs constitute our base models, as they combine scaled-solar isochrones with an empirical stellar spectral library [Medium resolution INT Library of Empirical Spectra (MILES)], which follows the chemical evolution pattern of the solar neighbourhood. The models rely as much as possible on empirical ingredients, not just on the stellar spectra, but also on extensive photometric libraries, which are used to determine the transformations from the theoretical parameters of the isochrones to observational quantities. The unprecedented stellar parameter coverage of the MILES stellar library allowed us to safely extend our optical SSP SED predictions from intermediate- to very-old-age regimes and the metallicity coverage of the SSPs from super-solar to [M/H]=-2.3. SSPs with such low metallicities are particularly useful for globular cluster studies. We have computed SSP SEDs for a suite of initial mass function shapes and slopes. We provide a quantitative analysis of the dependence of the synthesized SSP SEDs on the (in)complete coverage of the stellar parameter space in the input library that not only shows that our models are of higher quality than those of other works, but also in which range of SSP parameters our models are reliable.
1634. MILES library of empirical spectra
ID:
ivo://CDS.VizieR/J/MNRAS/371/703
Title:
MILES library of empirical spectra
Short Name:
J/MNRAS/371/703
Date:
21 Oct 2021
Publisher:
CDS
Description:
A new stellar library developed for stellar population synthesis modelling is presented. The library consists of 985 stars spanning a large range in atmospheric parameters. The spectra were obtained at the 2.5-m Isaac Newton Telescope and cover the range 3525-7500{AA} at 2.3{AA} (full width at half-maximum) spectral resolution. The spectral resolution, spectral-type coverage, flux-calibration accuracy and number of stars represent a substantial improvement over previous libraries used in population-synthesis models.
1635. Milky Way nuclear disk KMOS survey
ID:
ivo://CDS.VizieR/J/A+A/649/A83
Title:
Milky Way nuclear disk KMOS survey
Short Name:
J/A+A/649/A83
Date:
22 Feb 2022
Publisher:
CDS
Description:
In the central few degrees of the bulge of the Milky Way there is a flattened structure of gas, dust, and stars, known as the central molecular zone, that is similar to nuclear disks in other galaxies. As a result of extreme foreground extinction, we possess only sparse information about the (mostly old) stellar population of the nuclear disk. In this work we present our KMOS spectroscopic survey of the stars in the nuclear disk reaching the old populations. To obtain an unbiased data set, we sampled stars in the full extinction range along each line of sight. We also observed reference fields in neighboring regions of the Galactic bulge. We describe the design and execution of the survey and present first results. We obtain spectra and five spectral indices of 3113 stars with a median S/N of 67 and measure radial velocities for 3051 stars. Of those, 2735 sources have sufficient S/N to estimate temperatures and metallicities from indices. We derive metallicities using the CO 2-0 and Na I K-band spectral features, where we derive our own empirical calibration using metallicities obtained with higher-resolution observations.We use 183 giant stars for calibration spanning in metallicity from -2.5 to 0.6dex and covering temperatures of up to 5500K. The derived index based metallicities deviate from the calibration values with a scatter of 0.32dex. The internal uncertainty of our metallicities is likely smaller. We use these metallicity measurements, together with the CO index, to derive effective temperatures using literature relations. We publish the catalog in this paper. Our data set complements Galactic surveys such as Gaia and APOGEE for the inner 200pc radius of the Milky Way, which is not readily accessible by those surveys owing to extinction. We will use the derived properties in future papers for further analysis of the nuclear disk.
1636. Millimeter wave spectra of carbonyl cyanide
ID:
ivo://CDS.VizieR/J/A+A/592/A43
Title:
Millimeter wave spectra of carbonyl cyanide
Short Name:
J/A+A/592/A43
Date:
21 Oct 2021
Publisher:
CDS
Description:
More than 30 cyanide derivatives of simple organic molecules have been detected in the interstellar medium, but only one dicarbonitrile has been found and that very recently. There is still a lack of high-resolution spectroscopic data particularly for dinitriles derivatives. The carbonyl cyanide molecule is a new and interesting candidate for astrophysical detection. It could be formed by the reaction of CO and CN radicals, or by substitution of the hydrogen atom by a cyano group in cyanoformaldehyde, HC(=O)CN, that has already been detected in the interstellar medium. The available data on the rotational spectrum of carbonyl cyanide is limited in terms of quantum number values and frequency range, and does not allow accurate extrapolation of the spectrum into the millimeter-wave range. To provide a firm basis for astrophysical detection of carbonyl cyanide we studied its millimeter-wave spectrum. Methods. The rotational spectrum of carbonyl cyanide was measured in the frequency range 152-308GHz and analyzed using Watson's A- and S-reduction Hamiltonians. The ground and first excited state of v5 vibrational mode were assigned and analyzed. More than 1100 distinct frequency lines of the ground state were fitted to produce an accurate set of rotational and centrifugal distortion constants up to the eighth order. The frequency predictions based on these constants should be accurate enough for astrophysical searches in the frequency range up to 500GHz and for transition involving energy levels with J<100 and Ka<42. Based on the results we searched for interstellar carbonyl cyanide in available observational data without success. Thus, we derived upper limits to its column density in different sources.
1637. Millimeter wave spectrum of methyl cyanate
ID:
ivo://CDS.VizieR/J/A+A/591/A75
Title:
Millimeter wave spectrum of methyl cyanate
Short Name:
J/A+A/591/A75
Date:
21 Oct 2021
Publisher:
CDS
Description:
The recent discovery of methyl isocyanate (CH_3_NCO) in Sgr B2(N) and Orion KL makes methyl cyanate (CH_3_OCN) a potential molecule in the interstellar medium. The aim of this work is to fulfill the first requirement for its unequivocal identification in space, i.e. the availability of transition frequencies with high accuracy. The room-temperature rotational spectrum of methyl cyanate was recorded in the millimeter wave domain from 130 to 350GHz. All rotational transitions revealed A-E splitting owing to methyl internal rotation and were globally analyzed using the ERHAM program. The data set for the ground torsional state of methyl cyanate exceeds 700 transitions within J"=10-35 and K"a=0-13 and newly derived spectroscopic constants reproduce the spectrum close to the experimental uncertainty. Spectral features of methyl cyanate were then searched for in Orion KL, Sgr B2(N), B1-b, and TMC-1 molecular clouds. Upper limits to the column density of methyl cyanate are provided.
1638. Millimeter wave spectrum of vinyl acetate
ID:
ivo://CDS.VizieR/J/A+A/577/A91
Title:
Millimeter wave spectrum of vinyl acetate
Short Name:
J/A+A/577/A91
Date:
21 Oct 2021
Publisher:
CDS
Description:
The recent discovery of methyl acetate in Orion KL makes vinyl acetate, CH3-(C=O)-O-CH=CH2, a potential molecule in the interstellar medium.We obtained very accurate spectroscopic constants in a comprehensive laboratory analysis of its rotational spectra which can be used to predict those transition frequencies towards interstellar sources. We present the experimental study and theoretical analysis of the ground torsional state of vinyl acetate in a large spectral range for astrophysical use. The room-temperature rotational spectrum of vinyl acetate has been measured from 125 to 305GHz to provide direct frequencies to the astronomical community. Additional measurements have also been made using a broadband CP-FTMWspectrometer in the region of 6 - 18 GHz. Transition lines, corresponding to the most stable conformer, have been observed and assigned. All the rotational transitions revealed the A-E splitting due to the methyl internal rotation and had to be treated with a specific internal rotation code (BELGI-Cs). We analyzed 2508 transitions up to J"=75 for vt=0 for the most stable conformer of vinyl acetate. The new lines were globally fitted with previously published data and 24 parameters of the Hamiltonian were accurately determined. The spectral features of vinyl acetate were then searched for in Orion KL. Using the whole line survey of Orion KL (80-280GHz) obtained with the IRAM 30m radio telescope we can provide only an upper limit to the column density of vinyl acetate. However, using the ALMA Science Verification data we obtain a tentative detection of this species that will require further search at other frequencies to confirm its presence in this high mass star forming region.
1639. Minerva-Australis radial velocity of AU Mic
ID:
ivo://CDS.VizieR/J/AJ/162/137
Title:
Minerva-Australis radial velocity of AU Mic
Short Name:
J/AJ/162/137
Date:
14 Mar 2022 08:18:00
Publisher:
CDS
Description:
We report measurements of the sky-projected spin-orbit angle for AU Mic b, a Neptune-size planet orbiting a very young (~20Myr) nearby pre-main-sequence M-dwarf star, which also hosts a bright, edge-on, debris disk. The planet was recently discovered from preliminary analysis of radial-velocity observations and confirmed to be transiting its host star from photometric data from the NASA's TESS mission. We obtained radial-velocity measurements of AU Mic over the course of two partially observable transits and one full transit of planet b from high-resolution spectroscopic observations made with the MINERVA-Australis telescope array. Only a marginal detection of the Rossiter-McLaughlin effect signal was obtained from the radial velocities, in part due to AU Mic being an extremely active star and the lack of full transit coverage plus sufficient out-of-transit baseline. As such, a precise determination of the obliquity for AU Mic b is not possible in this study and we find a sky-projected spin-orbit angle of {lambda}=47_-54_^+26^deg . This result is consistent with both the planet's orbit being aligned or highly misaligned with the spin axis of its host star. Our measurement independently agrees with, but is far less precise than observations carried out on other instruments around the same time that measure a low-obliquity orbit for the planet. AU Mic is the youngest exoplanetary system for which the projected spin-orbit angle has been measured, making it a key data point in the study of the formation and migration of exoplanets-particularly given that the system is also host to a bright debris disk.
1640. M31 integrated light abundances
ID:
ivo://CDS.VizieR/J/ApJ/704/385
Title:
M31 integrated light abundances
Short Name:
J/ApJ/704/385
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report the first detailed chemical abundances for five globular clusters (GCs) in M31 from high-resolution (R~25000) spectroscopy of their integrated light (IL). These GCs are the first in a larger set of clusters observed as part of an ongoing project to study the formation history of M31 and its GC population. The data presented here were obtained with the HIRES echelle spectrograph on the Keck I telescope and are analyzed using a new IL spectra analysis method that we have developed. In these clusters, we measure abundances for Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Y, and Ba, ages >=10Gyr, and a range in [Fe/H] of -0.9 to -2.2. As is typical of Milky Way GCs, we find these M31 GCs to be enhanced in the {alpha}-elements Ca, Si, and Ti relative to Fe.

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