- ID:
- ivo://CDS.VizieR/J/A+A/459/317
- Title:
- Line Frequencies for Uracil
- Short Name:
- J/A+A/459/317
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report new laboratory spectroscopic data on the nucleic acid uracil. The dataset has been extended both into the microwave and towards mm-wavelengths with the aim to provide accurate transition rest frequencies for astrophysical searches. The complete experimental linelist used for the analysis of the data is compiled in Table 2. Lines marked with an asterisk are taken from Brown et al. (1988, J. Mol. Struct. 190, 185 and J. Am. Chem. Soc. 110, 2329), all other lines have been measured in this work.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJS/210/23
- Title:
- Line intensities in CN transitions
- Short Name:
- J/ApJS/210/23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Line strengths have been calculated in the form of Einstein A coefficients and f-values for a large number of bands of the A^2^{Pi}-X^2^{Sigma}^+^ and B^2^{Sigma}^+^-X^2^{Sigma}^+^ systems and rovibrational transitions within the X^2^{Sigma}^+^ state of CN using Western's PGOPHER program. The J dependence of the transition dipole moment matrix elements (the Herman-Wallis effect) has been taken into account. Rydberg-Klein-Rees potential energy functions for the A^2^{Pi}, B^2^{Sigma}^+^, and X^2^{Sigma}^+^ states were computed using spectroscopic constants from the A^2^{Pi}-X^2^{Sigma}^+^ and B^2^{Sigma}^+^-X^2^{Sigma}^+^ transitions. New electronic transition dipole moment functions for these systems and a dipole moment function for the X^2^{Sigma}^+^ state were generated from high level ab initio calculations and have been used in Le Roy's LEVEL program to produce transition dipole moment matrix elements (including their J dependence) for a large number of vibrational bands. The program PGOPHER was used to calculate Einstein A coefficients, and a line list was generated containing the observed and calculated wavenumbers, Einstein A coefficients and f-values for 290 bands of the A^2^{Pi}-X^2^{Sigma}^+^ transition with v'=0-22, v"=0-15, 250 bands of the B^2^{Sigma}^+^-X^2^{Sigma}^+^ transition with v'=0-15, v"=0-15 and 120 bands of the rovibrational transitions within the X^2^{Sigma}^+^ state with v=0-15. The Einstein A coefficients have been used to compute radiative lifetimes of several vibrational levels of the A^2^{Pi} and B^2^{Sigma}^+^ states and the values compared with those available from previous experimental and theoretical studies.
413. Line list
- ID:
- ivo://CDS.VizieR/J/A+A/598/A54
- Title:
- Line list
- Short Name:
- J/A+A/598/A54
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Blue metal-poor stars (BMPs) are main sequence stars that appear bluer and more luminous than normal turnoff stars. They were originally singled out by using B-V and U-B colour cuts. Early studies found that a larger fraction of field BMPs stars were binaries compared to normal halo stars. Thus, BMP stars are ideal field blue straggler candidates for investigating internal stellar evolution processes and binary interaction. In particular, the presence or depletion in lithium in their spectra is a powerful indicator of their origin. They are either old, halo blue stragglers experiencing internal mixing processes or mass transfer (Li-depletion), or intermediate-age, single stars of possibly extragalactic origin (2.2dex halo plateau Li). However, we note that internal mixing processes can lead to an increased level of Li. Hence, this study combines photometry and spectroscopy to unveil the origin of various BMP stars. We first show how to separate binaries from young blue stars using photometry, metallicity and lithium. Using a sample of 80 BMP stars (T>6300K), we find that 97% of the BMP binaries have (V-Ks)0<1.08+/-0.03, while BMP stars that are not binaries lie above this cut in two thirds of the cases. This cut can help classify stars that lack radial velocities from follow-up observations. We then trace the origin of two BMP stars from the photometric sample by conducting a full chemical analysis using new high-resolution and high signal-to-noise spectra. Based on their radial velocities, Li, {alpha} and s- and r-process abundances we show that BPS CS22874-042 is a single star (A(Li)=2.38+/-0.10dex) while with A(Li)=2.23+/-0.07dex CD-48 2445 is a binary, contrary to earlier findings. Our analysis emphasises that field blue stragglers can be segregated from single metal-poor stars, using (V-Ks) colours with a fraction of single stars polluting the binary sample, but not vice versa. These two groups can only be properly separated by using information from stellar spectra, illustrating the need for accurate and precise stellar parameters and high-resolution, high-S/N spectra in order to fully understand and classify this intriguing class of stars. Our high-resolution spectrum analysis confirms the findings from the colour cuts and shows that CS 22874-042 is single, while CD -48 2445 is most likely a binary. Moreover, the stellar abundances show that both stars formed in situ; CS 22874-042 carry traces of massive star enrichment and CD -48 2445 shows indications of AGB mass transfer mixed with gases ejected possibly from neutron star mergers.
414. Line list
- ID:
- ivo://CDS.VizieR/J/A+A/655/A26
- Title:
- Line list
- Short Name:
- J/A+A/655/A26
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- Recently, an increasing number of wide binaries has been discovered. Their chemical and dynamical properties are studied through extensive surveys and pointed observations. However, the formation of these wide binaries is far from clear, although several scenarios have been suggested. In order to investigate the chemical compositions of these systems, we analysed high-resolution spectroscopy of three wide binary pairs belonging to the Galactic halo. In total, another three candidates from our original sample of 11 candidates observed at various resolutions with various instruments were refuted as co-moving pairs because their radial velocities are significantly different. Within our sample of wide binaries, we found homogeneity amongst the pair components in dynamical properties (proper motion and line-of-sight velocities) and also in chemical composition. Their metallicities are -1.16, -1.42, and -0.79dex in [Fe/H] for each wide binary pair, which places these stars on the metal-poor side of wide binaries reported in the literature. In particular, the most metal-poor pair in our sample (WB2 = HD 134439/HD 134440) shows a lower [{alpha}/Fe] abundance ratio than Milky Way field stars, which is a clear signature of an accreted object. We also confirmed that this wide binary shares remarkably similar orbital properties with stars and globular clusters associated with the Sequoia event. Thus, it appears that the WB2 pair was formed in a dwarf galaxy environment and subsequently dissolved into the Milky Way halo. Although the other two wide binaries appear to arise from a different formation mechanism, our results provide a novel opportunity for understanding the formation of wide binaries and the assembly process of the Milky Way.
415. Line list
- ID:
- ivo://CDS.VizieR/J/AN/341/125
- Title:
- Line list
- Short Name:
- J/AN/341/125
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The precision differential abundance (PDA) technique is applied to the mid-F stars Procyon and Scl using spectra from the ESO UVESPOP library. We relate PDA patterns to endogenous processes related to condensation or to exogenous processes connected to Galactic chemical evolution (GCE). We employ one-dimensional LTE models, but emphasize the use of weaker lines (<=20m{AA}) than are typically used in such studies. We compare our results with PDAs of solar-type stars. Abundances and PDAs are determined for 28 elements: C, N, O, Na, Mg, Al, Si, S, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Ba, La, Ce, Nd, Sm, Eu, and Gd. A plot of PDAs ( Scl minus Procyon) vs. Z shows a highly significant correlation. Moreover, local substructure of the plot for the elements Ca-Zn and neutron-addition elements is similar to that which can be found for solar twins. Our PDA vs. Z plot structural similarity to plots that can be made from the extensive work of Bedell et al. (2018). That PDA structure and substructure is clearly a function of age.
416. Linelist
- ID:
- ivo://CDS.VizieR/J/A+A/643/A49
- Title:
- Linelist
- Short Name:
- J/A+A/643/A49
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A long sought after goal using chemical abundance patterns derived from metal- poor stars is to understand the chemical evolution of the Galaxy and to pin down the nature of the first stars (Pop III). Metal-poor, old, unevolved stars are excellent tracers as they preserve the abundance pattern of the gas from which they were born, and hence they are frequently targeted in chemical tagging studies. Here, we use a sample of 14 metal-poor stars observed with the high-resolution spectrograph called the Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI) at the Large Binocular Telescope (LBT) to derive abundances of 32 elements (34 including upper limits). We present well-sampled abundance patterns for all stars obtained using local thermodynamic equilibrium (LTE) radiative transfer codes and one-dimensional(1D) hydrostatic model atmospheres. However, it is currently well-known that the assumptions of 1D and LTE may hide several issues, thereby introducing biases in our interpretation as to the nature of the first stars and the chemical evolution of the Galaxy. Hence, we use non-LTE (NLTE) and correct the abundances using three-dimensional (3D) model atmospheres to present a physically more reliable pattern. In order to infer the nature of the first stars, we compare unevolved, cool stars, which have been enriched by a single event ('mono-enriched'), with a set of yield predictions to pin down the mass and energy of the Pop~III progenitor. To date, only few bona fide second generation stars that are mono-enriched are known. A simple chi^2^-fit may bias our inferred mass and energy just as much as the simple 1D LTE abundance pattern, and we therefore carried out our study with an improved fitting technique considering dilution and mixing. Our sample presents Carbon Enhanced Metal-Poor (CEMP) stars, some of which are promising bona fide second generation (mono-enriched) stars. The unevolved, dwarf BD+09 2190 shows a mono-enriched signature which, combined with kinematical data, indicates that it moves in the outer halo and likely has been accreted onto the Milky Way early on. The Pop~III progenitor was likely of 25.5M_{sun}_ and 0.6foe (0.6x10^51^erg) in LTE and 19.2M_{sun}_ and 1.5foe in NLTE, respectively. Finally, we explore the predominant donor and formation site of the rapid and slow neutron-capture elements. In BD-10 3742, we find an almost clean r-process trace, as is represented in the star HD20, which is a 'metal-poor Sun benchmark' for the r-process, while TYC5481-00786-1 is a promising CEMP-r/-s candidate that may be enriched by an asymptotic giant branch star of an intermediate mass and metallicity.
- ID:
- ivo://CDS.VizieR/J/A+A/561/A21
- Title:
- Line list for solar-type stars
- Short Name:
- J/A+A/561/A21
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The homogenization of the stellar parameters is an important goal for large observational spectroscopic surveys, but it is very difficult to achieve it because of the diversity of the spectroscopic analysis methods used within a survey, such as spectrum synthesis and the equivalent width method. To solve this problem, constraints to the spectroscopic analysis can be set, such as the use of a common line-list. We present a procedure for selecting the best spectral lines from a given input line-list, which then allows us to derive accurate stellar parameters with the equivalent width method.
- ID:
- ivo://CDS.VizieR/J/A+A/632/A55
- Title:
- Line list from Pal 13 sample stars
- Short Name:
- J/A+A/632/A55
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- At a Galactocentric distance of 27kpc, Palomar 13 is an old globular cluster (GC) belonging to the outer halo. We present a chemical abundance analysis of this remote system from high-resolution spectra obtained with the Keck/HIRES spectrograph. Owing to the low signal-to-noise ratio of the data, our analysis is based on a coaddition of the spectra of 18 member stars. We are able to determine integrated abundance ratios for 16 species of 14 elements, of {alpha}-elements (Mg, Si, Ca, and Ti), Fe-peak (Sc, Mn, Cr, Ni, Cu, and Zn), and neutron-capture elements (Y and Ba). While the mean Na abundance is found to be slightly enhanced and halo-like, our method does not allow us to probe an abundance spread that would be expected in this light element if multiple populations are present in Pal 13. We find a metal-poor mean metallicity of -1.91+/-0.05 (statistical) +/-0.22 (systematic), confirming that Pal 13 is a typical metal-poor representative of the outer halo. While there are some differences between individual {alpha}-elements, such as halo-like Mg and Si versus the mildly lower Ca and Ti abundances, the mean [{alpha}/Fe] of 0.34+/-0.06 is consistent with the marginally lower {alpha} component of the halo field and GC stars at similar metallicity. We discuss our results in the context of other objects in the outer halo and consider which of these objects were likely accreted. We also discuss the properties of their progenitors. While chemically, Pal 13 is similar to Gaia-Enceladus and some of its GCs, this is not supported by its kinematic properties within the Milky Way system. Moreover, its chemodynamical similarity with NGC 5466, a purported progeny of the Sequoia accretion event, might indicate a common origin in this progenitor. However, the ambiguities in the full abundance space of this comparison emphasize the difficulties in unequivocally labeling a single GC as an accreted object, let alone assigning it to a single progenitor.
- ID:
- ivo://CDS.VizieR/VI/121
- Title:
- Linelist of HCN and HNC
- Short Name:
- VI/121
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We build an accurate database of 5200 HCN and HNC rotation-vibration energy levels, determined from existing laboratory data. 20000 energy levels in the Harris et al., 2002ApJ...578..657H (HPT), linelist are assigned approximate quantum numbers. These assignments, lab determined energy levels and HPT energy levels are incorporated in to a new energy level list. A new linelist is presented, in which frequencies are computed using the available lab determined energy levels, and the HPT ab initio energy levels otherwise.
- ID:
- ivo://CDS.VizieR/J/A+A/506/845
- Title:
- Line list of HD 143418
- Short Name:
- J/A+A/506/845
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- HD 143418 was discovered recently to be a double-lined spectroscopic binary with a primary designated as a CP star. Its light displays an orbital phase coupled variability with a peak-to-peak amplitude up to 0.04mag. The photometry available and new high dispersion spectra were investigated from a point of view of CP characteristics. A series of high resolution high S/N coude spectra was acquired from which 25 weak to strong unblended lines of Fe I and II, Ti II, Cr II, Zr II, and Ba II were selected to study spectral line variability. Two Zeeman spectra were obtained to search for a possible magnetic field of the star, and one echelle spectrum in a wide spectral region was analysed for abundance determination by means of synthetic spectra. The photometric observations were subjected to a PCA disentangling of the complex photometric behaviour.
