- ID:
- ivo://CDS.VizieR/J/ApJ/899/145
- Title:
- Sulfur isotopes in SFR with 12m ARO and 30m IRAM
- Short Name:
- J/ApJ/899/145
- Date:
- 14 Mar 2022 07:08:41
- Publisher:
- CDS
- Description:
- We present observations of 12C32S, 12C34S, 13C32S, and 12C33S J=2-1 lines toward a large sample of massive star-forming regions by using the Arizona Radio Observatory 12m telescope and the IRAM 30m. Taking new measurements of the carbon 12C/13C ratio, the 32S/34S isotope ratio was determined from the integrated 13C32S/12C34S line intensity ratios for our sample. Our analysis shows a 32S/34S gradient from the inner Galaxy out to a galactocentric distance of 12kpc. An unweighted least-squares fit to our data yields 32S/34S=(1.56{+/-}0.17)DGC+(6.75{+/-}1.22) with a correlation coefficient of 0.77. Errors represent 1{sigma} standard deviations. Testing this result by (a) excluding the Galactic center region, (b) excluding all sources with C34S opacities >0.25, (c) combining our data and old data from previous study, and (d) using different sets of carbon isotope ratios leads to the conclusion that the observed 32S/34S gradient is not an artifact but persists irrespective of the choice of sample and carbon isotope data. A gradient with rising 32S/34S values as a function of galactocentric radius implies that the solar system ratio should be larger than that of the local interstellar medium. With the new carbon isotope ratios, we indeed obtain a local 32S/34S isotope ratio about 10% below the solar system one, as expected in the case of decreasing 32S/34S ratios with time and increased amounts of stellar processing. However, taking older carbon isotope ratios based on a lesser amount of data, such a decrease is not seen. No systematic variation of 34S/33S ratios along galactocentric distance was found. The average value is 5.9{+/-}1.5, the error denoting the standard deviation of an individual measurement.
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Search Results
21052. Sulphur in the Sculptor dSph
- ID:
- ivo://CDS.VizieR/J/A+A/580/A129
- Title:
- Sulphur in the Sculptor dSph
- Short Name:
- J/A+A/580/A129
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In Galactic halo stars, sulphur has been shown to behave like other {alpha}-elements, but until now, no comprehensive studies have been done on this element in stars of other galaxies. Here, we use high-resolution ESO VLT/FLAMES/GIRAFFE spectra to determine sulphur abundances for 85 stars in the Sculptor dwarf spheroidal galaxy, covering the metallicity range -2.5<=[Fe/H]<=-0.8. The abundances are derived from the SI triplet at 9213, 9228, and 9238{AA}. These lines have been shown to be sensitive to departure from local thermodynamic equilibrium, i.e. NLTE effects. Therefore, we present new NLTE corrections for a grid of stellar parameters covering those of the target stars. The NLTE-corrected sulphur abundances in Sculptor show the same behaviour as other {alpha}-elements in that galaxy (such as Mg, Si, and Ca). At lower metallicities ([Fe/H]<~-2) the abundances are consistent with a plateau at [S/Fe]=~+0.16, similar to what is observed in the Galactic halo, [S/Fe]=~+0.2. With increasing [Fe/H], the [S/Fe] ratio declines, reaching negative values at [Fe/H]>-1.5. The sample also shows an increase in [S/Mg] with [Fe/H], most probably because of enrichment from Type Ia supernovae.
- ID:
- ivo://CDS.VizieR/J/A+A/533/A87
- Title:
- Sulphur ions iso-electronic sequence
- Short Name:
- J/A+A/533/A87
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present our calculated data including energy levels, radiative decay rates and effective collision strengths for all the transitions among fine-structure levels of n=3 or 4 configurations, for four iso-nuclear ions, viz S^8+^, S^9+^, S^10+^ and S^11+^.
21054. SUMaC I
- ID:
- ivo://CDS.VizieR/J/MNRAS/466/4540
- Title:
- SUMaC I
- Short Name:
- J/MNRAS/466/4540
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first results from the Swift Ultraviolet Survey of the Magellanic Clouds, the highest resolution ultraviolet (UV) survey of the Magellanic Clouds yet completed. In this paper, we focus on the Small Magellanic Cloud (SMC). When combined with multiwavelength optical and infrared observations, the three near-UV filters on the Swift Ultraviolet/Optical Telescope are conducive to measuring the shape of the dust extinction curve and the strength of the 2175{AA} dust bump. We divide the SMC into UV-detected star-forming regions and large 200-arcsec (58pc) pixels and then model the spectral energy distributions using a Markov-chain Monte Carlo method to constrain the ages, masses, and dust curve properties. We find that the majority of the SMC has a 2175{AA} dust bump, which is larger to the north-east and smaller to the south-west, and that the extinction curve is predominantly steeper than the Galactic curve. We also derive a star formation history and find evidence for peaks in the star formation rate at 6-10, 30-80, and 400Myr, the latter two of which are consistent with previous work.
- ID:
- ivo://CDS.VizieR/J/A+A/375/591
- Title:
- SUMER Spectral Atlas of Solar Disk Features
- Short Name:
- J/A+A/375/591
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- List of spectral lines in the wavelength range from 668{AA} to 1611{AA} identified in SUMER (Solar Ultraviolet Measurements of Emitted Radiation, spectrograph on the spacecraft SOHO) spectra of the average quiet Sun (QS), a coronal hole (CH) and a sunspot on disk (SS). Spectral lines observed in second order of diffraction which are also given here, extend the lower wavelength limit to below 500{AA}. For each entry we give the observed wavelengths in angstrom, the identification, the transition, the peak of spectral radiance, L^peak^, in mW/(sr*m^2^*{AA}) (incl. background), and a cross-reference to other line lists available in the literature (cf., Sect. 5.1). For second-order lines radiance entries are generally not provided, since the background separation in both orders of diffraction is a non-trivial task, which can not be automated. Only a few radiance values of strong second-order lines with negligible first-order contribution are given, which are marked by an asterisk (*).
21056. SUMSS Giant Radio Sources
- ID:
- ivo://CDS.VizieR/J/AJ/130/896
- Title:
- SUMSS Giant Radio Sources
- Short Name:
- J/AJ/130/896
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a complete sample of megaparsec-sized double radio sources compiled from the Sydney University Molonglo Sky Survey (SUMSS, Cat. <VIII/70>). Almost complete redshift information has been obtained for the sample. The sample has the following defining criteria: Galactic latitude |b|>12.5{deg}, declination {delta}<-50{deg}, and angular size >5'. All the sources have a projected linear size larger than 0.7Mpc (assuming H_0_=71km/s/Mpc). The sample is chosen from a region of the sky covering 2100{deg}^2^. In this paper we present 843MHz radio images of the extended radio morphologies made using the Molonglo Observatory Synthesis Telescope, higher resolution radio observations of any compact radio structures using the Australia Telescope Compact Array, and low-resolution optical spectra of the host galaxies from the 2.3m Australian National University telescope at Siding Spring Observatory. The sample presented here is the first in the southern hemisphere and significantly enhances the database of known giant radio sources. The giant radio sources with linear size exceeding 0.7Mpc have an abundance of (215Mpc)^-3^ at the sensitivity of the survey. In the low-redshift universe, the survey may be suggesting the possibility that giant radio sources with relict lobes are more numerous than giant sources in which beams from the center currently energize the lobes.
- ID:
- ivo://CDS.VizieR/J/ApJ/871/16
- Title:
- Sun active regions from 1976-2017
- Short Name:
- J/ApJ/871/16
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The purpose of this paper is to show that large active regions (ARs) with different magnetic configurations have different contributions to short-term and long-term variations of the Sun. As a case study, the complex {delta}-type AR12673 and the simple {beta}-type AR12674 are investigated in detail. Since the axial dipole moment at cycle minimum determines the amplitude of the subsequent cycle and space climate, we have assimilated the individual observed magnetic configurations of these two ARs into a surface flux transport model to compare their contributions to the axial dipole moment D. We find that AR12673 has a significant effect on D at the end of the cycle, making it weaker because of abnormal and complicated magnetic polarities. An initial strongly positive D ends up with a strongly negative value. The flare- poor AR12674 has a greater contribution to the long-term axial dipole moment than the flare-rich AR12673. We then carry out a statistical analysis of ARs larger than 800{mu}Hem (solar hemisphere) from 1976 to 2017. We use the flare index (FI) and define an axial dipole moment index (DI) to quantify the effects of each AR on space weather and space climate, respectively. Whereas the FI has a strong dependence on the magnetic configuration, the DI shows no such dependence. The DI is mainly determined by the latitudinal location and the latitudinal separation of the positive and negative magnetic fluxes of the ARs. Simple ARs have the same possibility as complex ARs to produce big DI values affecting space climate.
- ID:
- ivo://CDS.VizieR/J/ApJS/208/27
- Title:
- Sun and HD 84937 TiII log(gf) and abundances
- Short Name:
- J/ApJS/208/27
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Atomic transition probability measurements for 364 lines of Ti II in the UV through near-IR are reported. Branching fractions from data recorded using a Fourier transform spectrometer (FTS) and a new echelle spectrometer are combined with published radiative lifetimes to determine these transition probabilities. The new results are in generally good agreement with previously reported FTS measurements. Use of the new echelle spectrometer, independent radiometric calibration methods, and independent data analysis routines enables a reduction of systematic errors and overall improvement in transition probability accuracy over previous measurements. The new Ti II data are applied to high-resolution visible and UV spectra of the Sun and metal-poor star HD 84937 to derive new, more accurate Ti abundances. Lines covering a range of wavelength and excitation potential are used to search for non-LTE effects. The Ti abundances derived using Ti II for these two stars match those derived using Ti I and support the relative Ti/Fe abundance ratio versus metallicity seen in previous studies.
- ID:
- ivo://CDS.VizieR/J/A+A/552/A114
- Title:
- Sun chromospheric CaII-HK emission
- Short Name:
- J/A+A/552/A114
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Monitoring of the photometric and chromospheric HK emission data series of stars similar to the Sun in age and average activity level showed that there is an empirical correlation between the average stellar chromospheric activity level and the photometric variability. In general, more active stars show larger photometric variability. Interestingly, the measurements and reconstructions of the solar irradiance show that the Sun is significantly less variable than indicated by the empirical relationship. We aim to identify possible reasons for the Sun to be currently outside of this relationship. We employed different scenarios of solar HK emission and irradiance variability and compared them with available time series of Sun-like stars.
21060. Sun observations in 1992
- ID:
- ivo://CDS.VizieR/J/A+AS/110/351
- Title:
- Sun observations in 1992
- Short Name:
- J/A+AS/110/351
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The results of an observational campaign of the Sun are reported.
