| 1. |
- de Jong, R. S., et al.
(författare)
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4MOST : Project overview and information for the First Call for Proposals
- 2019
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Ingår i: The Messenger. - : European Southern Observatory. - 0722-6691. ; 175, s. 3-11
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- We introduce the 4-metre Multi-Object Spectroscopic Telescope (4MOST), a new high-multiplex, wide-field spectroscopic survey facility under development for the four-metre-class Visible and Infrared Survey Telescope for Astronomy (VISTA) at Paranal. Its key specifications are: a large field of view (FoV) of 4.2 square degrees and a high multiplex capability, with 1624 fibres feeding two low-resolution spectrographs (R = λ/Δλ ~ 6500), and 812 fibres transferring light to the high-resolution spectrograph (R ~ 20 000). After a description of the instrument and its expected performance, a short overview is given of its operational scheme and planned 4MOST Consortium science; these aspects are covered in more detail in other articles in this edition of The Messenger. Finally, the processes, schedules, and policies concerning the selection of ESO Community Surveys are presented, commencing with a singular opportunity to submit Letters of Intent for Public Surveys during the first five years of 4MOST operations.
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| 2. |
- Song, C. X., et al.
(författare)
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Extended calculations with spectroscopic accuracy : Energy levels and radiative rates for O-like ions between Ar XI and Cr XVII
- 2021
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Ingår i: Atomic Data and Nuclear Data Tables. - : Elsevier. - 0092-640X .- 1090-2090. ; 138
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Tidskriftsartikel (refereegranskat)abstract
- Using the multiconfiguration Dirac-Hartree-Fock and the relativistic configuration interaction methods, a consistent set of transition energies and radiative transition data for the main states of the 2s(2)2p(4), 2s2p(5), 2p(6), 2s(2)2p(3)3s, 2s(2)2p(3)3p, 2s(2)2p(3)3d, 2s2p(4)3s, 2s2p(4)3p, and 2s2p(4)3d configurations in O-like Ions between Ar XI (Z = 18) and Cr XVII (Z = 24) is provided. Our data set is compared with the NIST compiled values and previous calculations. The data are accurate enough for identification and deblending of new emission lines from hot astrophysical and laboratory plasmas. The amount of data of high accuracy is significantly increased for the n = 3 states of several O-like ions, where experimental data are very scarce. (c) 2020 Elsevier Inc. All rights reserved.
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| 3. |
- Wang, Kai, et al.
(författare)
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Energy levels, lifetimes and radiative rates for transitions in the bromine isoelectronic sequence La XXIII-Dy XXXII, W XL
- 2018
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Ingår i: Atomic Data and Nuclear Data Tables. - : Elsevier. - 0092-640X .- 1090-2090. ; 123, s. 114-167
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Tidskriftsartikel (refereegranskat)abstract
- Using the multiconfiguration Dirac-Fock method, calculations for the lowest 62 levels of the ([Ar] 3d(10))4s(2) 4p(5), ([Ar] 3d(10))4s(2)4p(3)4d(2), ([Ar] 3d(10))4s(2)4p(4)4d, ([Ar] 3d(10))4s4p(6), and ([Ar] 3d(10))4s4p(5)4d configurations are performed for the bromine isoelectronic sequence La XXIII-Dy XXXII, W XL. Results of energy levels, lifetimes, wavelengths, and electric dipole, magnetic dipole, electric quadrupole, and magnetic quadrupole radiative rates are presented. In order to assess the accuracy of results, independent calculations for W XL have been carried out using the many-body perturbation theory (MBPT) method. Comparisons are made with available theoretical results from other calculations and the observed values of the Atomic Spectra Database of the National Institute of Standards and Technology. Energy levels are estimated to be accurate to better than 1%, and radiative rates (and lifetimes) are accurate to better than 20% for a majority of strong transitions. These results should be useful in many applications of lanthanide ions related to broad area of research such as applied physics, laser physics and fusion science. (C) 2017 Elsevier Inc. All rights reserved.
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| 4. |
- Wang, Kai, et al.
(författare)
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Extended calculations of energy levels, radiative properties, A(J), B-J hyperfine interaction constants, and Lande g(J)-factors for nitrogen-like Ge XXVI
- 2018
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Ingår i: Journal of Quantitative Spectroscopy and Radiative Transfer. - : Pergamon Press. - 0022-4073 .- 1879-1352. ; 208, s. 134-151
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Tidskriftsartikel (refereegranskat)abstract
- Employing two state-of-the-art methods, multiconfiguration Dirac-Hartree-Fock and second-order many body perturbation theory, highly accurate calculations are performed for the lowest 272 fine -structure levels arising from the 2s(2)2p(3), 2s(2)p(4), 2p(5), 2s(2)2p(2)3l (l = s, p, d), 2s2p(3)3l (l = s, p, d), and 2p(4)3l (l = s, p. d) configurations in nitrogen-like Ge XXVI. Complete and consistent atomic data, including excitation energies, lifetimes, wavelengths, hyperfine structures, Lande g(J)-factors, and E1, E2, M1, M2 line strengths, oscillator strengths, and transition rates among these 272 levels are provided. Comparisons are made between the present two data sets, as well as with other available experimental and theoretical values. The present data are accurate enough for identification and deblending of emission lines involving the n = 3 levels, and are also useful for modeling and diagnosing fusion plasmas. (C) 2018 Elsevier Ltd. All rights reserved.
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| 5. |
- Blanton, Michael R., et al.
(författare)
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Sloan Digital Sky Survey IV : Mapping the Milky Way, Nearby Galaxies, and the Distant Universe
- 2017
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Ingår i: Astronomical Journal. - : IOP Publishing Ltd. - 0004-6256 .- 1538-3881. ; 154:1
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Tidskriftsartikel (refereegranskat)abstract
- We describe the Sloan Digital Sky Survey IV (SDSS-IV), a project encompassing three major spectroscopic programs. The Apache Point Observatory Galactic Evolution Experiment 2 (APOGEE-2) is observing hundreds of thousands of Milky Way stars at high resolution and. high signal-to-noise ratios in the near-infrared. The Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey is obtaining spatially resolved spectroscopy for thousands of nearby galaxies (median z similar to 0.03). The extended Baryon Oscillation Spectroscopic Survey (eBOSS) is mapping the galaxy, quasar, and neutral gas distributions between z similar to 0.6 and 3.5 to constrain cosmology using baryon acoustic oscillations, redshift space distortions, and the shape of the power spectrum. Within eBOSS, we are conducting two major subprograms: the SPectroscopic IDentification of eROSITA Sources (SPIDERS), investigating X-ray AGNs. and galaxies in X-ray clusters, and the Time Domain Spectroscopic Survey (TDSS), obtaining spectra of variable sources. All programs use the 2.5 m Sloan Foundation Telescope at the. Apache Point Observatory; observations there began in Summer 2014. APOGEE-2 also operates a second near-infrared spectrograph at the 2.5 m du Pont Telescope at Las Campanas Observatory, with observations beginning in early 2017. Observations at both facilities are scheduled to continue through 2020. In keeping with previous SDSS policy, SDSS-IV provides regularly scheduled public data releases; the first one, Data Release 13, was made available in 2016 July.
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| 6. |
- Song, C.X., et al.
(författare)
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Large-scale multiconfiguration Dirac-Hartree-Fock calculations for astrophysics : n=4 levels in P-like ions from Mn XIto Ni XIV
- 2020
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Ingår i: Astrophysical Journal Supplement Series. - : Institute of Physics (IOP). - 0067-0049 .- 1538-4365. ; 247:70, s. 1-11
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Tidskriftsartikel (refereegranskat)abstract
- Using the multiconfiguration Dirac–Hartree–Fock and the relativistic configuration interaction methods, a consistent set of transition energies and radiative transition data for the lowest 546 (623, 701, and 745) states of the , , , , , , , , , , , , , , , and configurations in Mn xi (Fe xii, Co xiii, and Ni xiv) is provided. The comparison between calculated excitation energies for the n = 4 states and available experimental values for Fe xii indicate that the calculations are highly accurate, with uncertainties of only a few hundred cm−1. Lines from these states are prominent in the soft X-rays. With the present calculations, several recent new identifications are confirmed. Other identifications involving levels in Fe xii that were found to be questionable are discussed and a few new assignments are recommended. As some n = 4 states of the other ions also show large discrepancies between experimental and calculated energies, we reassess their identification. The present study provides highly accurate atomic data for the n = 4 states of P-like ions of astrophysical interest, for which experimental data are scarce.
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| 7. |
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The Seventeenth Data Release of the Sloan Digital Sky Surveys : Complete Release of MaNGA, MaStar, and APOGEE-2 Data
- 2022
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Ingår i: Astrophysical Journal Supplement Series. - : Institute of Physics (IOP). - 0067-0049 .- 1538-4365. ; 259:2
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Tidskriftsartikel (refereegranskat)abstract
- This paper documents the seventeenth data release (DR17) from the Sloan Digital Sky Surveys; the fifth and final release from the fourth phase (SDSS-IV). DR17 contains the complete release of the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey, which reached its goal of surveying over 10,000 nearby galaxies. The complete release of the MaNGA Stellar Library accompanies this data, providing observations of almost 30,000 stars through the MaNGA instrument during bright time. DR17 also contains the complete release of the Apache Point Observatory Galactic Evolution Experiment 2 survey that publicly releases infrared spectra of over 650,000 stars. The main sample from the Extended Baryon Oscillation Spectroscopic Survey (eBOSS), as well as the subsurvey Time Domain Spectroscopic Survey data were fully released in DR16. New single-fiber optical spectroscopy released in DR17 is from the SPectroscipic IDentification of ERosita Survey subsurvey and the eBOSS-RM program. Along with the primary data sets, DR17 includes 25 new or updated value-added catalogs. This paper concludes the release of SDSS-IV survey data. SDSS continues into its fifth phase with observations already underway for the Milky Way Mapper, Local Volume Mapper, and Black Hole Mapper surveys.
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| 8. |
- Wang, K., et al.
(författare)
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Benchmarking Atomic Data from Large-scale Multiconfiguration Dirac Hartree Fock Calculations for Astrophysics : S-like Ions from Cr IX to Cu XIV
- 2018
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Ingår i: Astrophysical Journal Supplement Series. - : Bibliopolis, Edizioni di Filosofia e Scienze. - 0067-0049 .- 1538-4365. ; 239:2
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Tidskriftsartikel (refereegranskat)abstract
- We present a consistent set of calculated energies and El, Ml, E2, M2 radiative transition data for the main n = 3 levels from the 3s(2)3p(4), 3p(6), 3s3p(4)3d, 3s(2)3p(2)3d(2), 3s3p(5), 3s(2)3p(3)3d, and 3s3p(3)3d(2) configurations for S-like ions from Cr TX to Cu XIV. The fully relativistic multiconfiguration Dirac Hartree Fock method implemented in the GRASP2K code is used to perform the present calculations. The excitation energies of the lowest 47 levels from the 3s(2)3p(4), 3s3p(5), and 3s(2)3p3 3d configurations, producing the strongest lines, are found to be in good agreement, reaching spectroscopic accuracy, with the latest experimental values for Fe XI evaluated by Del Zanna. Our energies can reliably be used to identify in astrophysical and laboratory spectra the 3s(2)3p(3) 3d levels in other S-like ions, which are mostly unknown. On the contrary, significant discrepancies with the 3s3p(4)3d levels were found, emphasizing the need for more detailed experimental studies. A few new tentative identifications are suggested. The benchmarks we present indicate that our consistent set of radiative data is accurate and can be used for spectral line modeling.
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