Article
Astronomy & Astrophysics
Meenakshi Purandardas, Aruna Goswami, J. Shejeelammal, Mayani Sonamben, Ganesh Pawar, David Mkrtichian, Vijayakumar H. Doddamani, Santosh Joshi
Summary: This article presents the results of a high-resolution spectroscopic analysis of a star from the list of carbon stars of LAMOST DR2. The star, named J045, does not exhibit the spectral characteristics of carbon stars and has elemental abundances that closely resemble those found in stars from the Sculptor Dwarf galaxy. Based on these findings, it is suggested that J045 may be an escapee from the Sculptor Dwarf Galaxy.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
M. P. Roriz, C. B. Pereira, S. Junqueira, M. Lugaro, N. A. Drake, C. Sneden
Summary: We present detailed chemical compositions of four chemically peculiar stars on the first-ascent red giant branch, which lack high spectral resolution comprehensive analyses. These stars, BD+03 degrees 2688, HE 0457-1805, HE 1255-2324, and HE 2207-1746, exhibit a range in Galactic population membership with metallicities of [Fe/H] = -1.21, -0.19, -0.31, and -0.55, respectively. We obtained elemental abundances for 28 elements, including CNO group and C-12/C-13 ratios, as well as novel results for the heavy elements tungsten and thallium. All four stars show significant enhancements of neutron-capture elements, indicating enrichments from the slow neutron capture (s-process).
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Federico Sestito, Daria Zaremba, Kim A. Venn, Lina D'Aoust, Christian Hayes, Jaclyn Jensen, Julio F. Navarro, Pascale Jablonka, Emma Fernandez-Alvar, Jennifer Glover, Alan W. Mcconnachie, Andre-Nicolas Chene
Summary: Stellar candidates in the extreme outskirts of the Ursa Minor dwarf galaxy have been discovered and confirmed to be part of the galaxy through observations and chemical analysis. The chemical patterns in UMi suggest an outside-in star-formation history and a low star-formation efficiency. Additionally, the analysis of the surface number density profile indicates that UMi's outskirts have been influenced by tidal effects.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
H. Ernandes, M. J. Castro, B. Barbuy, M. Spite, V Hill, B. Castilho, C. J. Evans
Summary: We examined the abundances of neutron-capture elements in the metal-poor r-process-rich halo star CS 31082-001 with an expanded line list for heavy elements. Using archival near-ultraviolet spectra, we analyzed the abundances and nucleosynthesis of 35 heavy elements. Our results show that the r-process-dominated elements are as enhanced as those in the Sun, but the lighter elements do not follow the solar abundance pattern. Furthermore, we found deficiencies in the abundance of tin and suggest further investigation on the origin and evolution of metal-poor stars.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
H. Ernandes, B. Barbuy, A. Friaca, V Hill, M. Spite, F. Spite, B. Castilho, C. J. Evans
Summary: The study reveals that the metal-poor star CS 31082-001 is rich in r-process and actinide elements, with the first measurement of uranium abundance in an old star. The abundance estimates of beryllium, vanadium, and copper in CS 31082-001 are presented, showing that beryllium is low due to the cool temperature, while vanadium and copper have comparable abundances to other metal-poor stars. New chemical evolution models are proposed to investigate the results, and the study also explores other atomic lines in the near-ultraviolet for future studies of metal-poor stars.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Rafael Costero, Christine Allen, Alex Ruelas-Mayorga, Leonardo Sanchez, Julio Ramirez Velez, Juan Echevarria, Gustavo C. Melgoza
Summary: The analysis of Echelle spectra of theta(1) Ori F reveals it to be a chemically peculiar star with overabundant silicon and phosphorus, with a potentially variable radial velocity. This star may play a crucial role in understanding the evolutionary stage at which the CP phenomenon sets on.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
L. Freour, C. Neiner, J. D. Landstreet, C. P. Folsom, G. A. Wade
Summary: We conducted a spectropolarimetric analysis of the hot star V352 Peg. The analysis showed that the star is a chemically peculiar Bp star with overabundances of iron peak elements and underabundance of He and O. We detected a magnetic field in V352 Peg and determined its geometrical configuration through modelling and Zeeman-Doppler Imaging.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Chris Koen, Cole Johnston
Summary: Theta Car is a bright and well-studied B0 type star in a close binary system with an unseen companion, which has been extensively characterized at multiple wavelengths. Recent observations using the NASA TESS satellite show that the photometric variability of the star may be associated with surface brightness inhomogeneities.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Danielle de Brito Silva, Paula Jofre, Douglas Bourbert, Sergey E. Koposov, Jose L. Prieto, Keith Hawkins
Summary: Our study reveals that J01020100-7122208 is a star with a retrograde and highly-eccentric orbit, likely accreted by the Milky Way in the distant past. Its mass and age suggest it is probably an evolved blue straggler.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
James M. Nemec, Pawel Moskalik
Summary: This study identified four stars pulsating simultaneously with dominant periods and analysed their light variations. The research confirmed these stars as pRRd stars, a separate group of double-mode pulsators, rather than simply very short-period cRRd stars.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
T. T. Hansen, J. D. Simon, T. S. Li, A. Frebel, I. Thompson, S. Shectman
Summary: Carbon-enhanced metal-poor (CEMP) stars are important tracers of early Galactic chemical evolution. This study focuses on six CEMP stars in the Carina dSph and compares their abundances to CEMP stars in other dSph galaxies and the Milky Way halo. Detailed elemental abundances were derived through spectroscopic analysis.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
L. Mashonkina, A. Arentsen, D. S. Aguado, A. Smogorzhevskii, M. Hampel, A. Karakas, F. Sestito, N. F. Martin, K. A. Venn, J. I. Gonzalez Hernandez
Summary: This study presents high-resolution spectroscopic follow-up of the carbon-enhanced metal-poor star Pristine 184237. The atmospheric parameters and abundances for 32 elements were determined, revealing unique element abundance patterns. It is the first star of the CEMP-r/s subclass identified in the inner Galaxy.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
O. Kobzar, V Khalack, D. Bohlender, G. Mathys, M. E. Shultz, D. M. Bowman, E. Paunzen, C. Lovekin, A. David-Uraz, J. Sikora, P. Lampens, O. Richard
Summary: This study used TESS data to investigate the rotational periods of chemically peculiar stars, and found that the critical rotational fractions decrease with stellar age.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
G. Tautvaisiene, A. Drazdauskas, A. Bragaglia, S. L. Martell, E. Pancino, C. Lardo, S. Mikolaitis, R. Minkeviciute, E. Stonkute, M. Ambrosch, V. Bagdonas, Y. Chorniy, N. Sanna, E. Franciosini, R. Smiljanic, S. Randich, G. Gilmore, T. Bensby, M. Bergemann, A. Gonneau, G. Guiglion, G. Carraro, U. Heiter, A. Korn, L. Magrini, L. Morbidelli, S. Zaggia
Summary: The study aimed to determine carbon, nitrogen, and oxygen abundances for evolved giants in the globular cluster NGC 1851 to investigate the coeval nature of the double populations of stars. The results showed differences in mean metallicity, C/N ratio, and s-process dominated element-to-iron abundance ratios between the two populations, suggesting that NGC 1851 is composed of two clusters with different ages.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
L. Mashonkina, Yu Pakhomov, T. Sitnova, P. Jablonka, S. A. Yakovleva, A. K. Belyaev
Summary: This study presents accurate atmospheric parameters and NLTE abundances for very metal-poor stars in the Sextans dwarf spheroidal galaxy. The stars exhibit alpha-enhancements and a tight relationship between Ba and Mg, suggesting a common origin in massive stars. Additionally, the study reveals a decline in alpha/Fe for stars with higher [Fe/H] values and a distinctive Ba enrichment pattern in one C-enhanced star.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Dentistry, Oral Surgery & Medicine
K. Edman, A. Holmlund, B. Nordstrom, K. Ohrn
INTERNATIONAL JOURNAL OF DENTAL HYGIENE
(2018)
Article
Astronomy & Astrophysics
P. Francois, E. Caffau, P. Bonifacio, M. Spite, F. Spite, R. Cayrel, N. Christlieb, A. J. Gallagher, R. Klessen, A. Koch, H. -G. Ludwig, L. Monaco, B. Plez, M. Steffen, S. Zaggia
ASTRONOMY & ASTROPHYSICS
(2018)
Article
Astronomy & Astrophysics
C. J. Hansen, T. T. Hansen, A. Koch, T. C. Beers, B. Nordstrom, V. M. Placco, J. Andersen
ASTRONOMY & ASTROPHYSICS
(2019)
Article
Astronomy & Astrophysics
E. Tempel, P. Norberg, T. Tuvikene, T. Bensby, C. Chiappini, N. Christlieb, M. -R. L. Cioni, J. Comparat, L. J. M. Davies, G. Guiglion, A. Koch, G. Kordopatis, M. Krumpe, J. Loveday, A. Merloni, G. Micheva, I. Minchev, B. F. Roukema, J. G. Sorce, E. Starkenburg, J. Storm, E. Swann, W. F. Thi, G. Traven, R. S. de Jong
ASTRONOMY & ASTROPHYSICS
(2020)
Article
Astronomy & Astrophysics
E. Tempel, T. Tuvikene, M. M. Muru, R. S. Stoica, T. Bensby, C. Chiappini, N. Christlieb, M-R L. Cioni, J. Comparat, S. Feltzing, I Hook, A. Koch, G. Kordopatis, M. Krumpe, J. Loveday, I Minchev, P. Norberg, B. F. Roukema, J. G. Sorce, J. Storm, E. Swann, E. N. Taylor, G. Traven, C. J. Walcher, R. S. de Jong
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2020)
Article
Astronomy & Astrophysics
G. Cescutti, C. Morossi, M. Franchini, P. Di Marcantonio, C. Chiappini, M. Steffen, M. Valentini, P. Francois, N. Christlieb, C. Cortes, C. Kobayashi, E. Depagne
Summary: Researchers analyzed the barium lines in two halo stars, HD 6268 and HD 4306, finding that the former showed an s-process composition while the latter displayed an r-process isotopic pattern. This confirms the theoretical expectation that both r-process events and s-process contribution by rotating massive stars have affected the ancient halo of our Galaxy.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
P. Bonifacio, L. Monaco, S. Salvadori, E. Caffau, M. Spite, L. Sbordone, F. Spite, H. -G. Ludwig, P. Di Matteo, M. Haywood, P. Francois, A. J. Koch-Hansen, N. Christlieb, S. Zaggia
Summary: This study utilized SDSS and Gaia data to estimate the metallicity of over 24 million TO stars and found a strong bias towards metal-poor stars in the SDSS spectroscopic sample. By comparing with the unbiased photometric sample, the selection bias was corrected, and a sub-sample of stars with reliable parallaxes was characterized for their dynamical properties.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
T. Xylakis-Dornbusch, N. Christlieb, K. Lind, T. Nordlander
Summary: This study uses flux ratios from Gaia spectra to identify metal-poor stars and infer the iron abundance within a large uncertainty range. The study discovers a relationship between iron abundance and the flux ratio of the Ca H & K region to the H beta line, which is successfully applied to noisy synthetic spectra for reliable identification of metal-poor stars. By selecting stars with lower inferred abundances, it is possible to detect a high proportion of stars with core abundances below -3.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
Wako Aoki, Haining Li, Tadafumi Matsuno, Qianfan Xing, Yuqin Chen, Norbert Christlieb, Satoshi Honda, Miho N. Ishigaki, Jianrong Shi, Takuma Suda, Nozomu Tominaga, Hong-Liang Yan, Jingkun Zhao, Gang Zhao
Summary: The chemical abundances of very metal-poor stars provide constraints on the nucleosynthesis of the first generation of stars and early chemical evolution of the Galaxy. This study obtained high-resolution spectra for about 400 very metal-poor stars and discussed the kinematics of the sample. It also identified seven double-lined spectroscopic binaries and discussed their frequency at very low metallicity.
ASTROPHYSICAL JOURNAL
(2022)
Article
Astronomy & Astrophysics
Chris Evans, Stefano Cristiani, Cyrielle Opitom, Gabriele Cescutti, Valentina D'Odorico, Juan Manuel Alcala, Silvia H. P. Alencar, Sergei Balashev, Beatriz Barbuy, Nate Bastian, Umberto Battino, Pamela Cambianica, Roberta Carini, Brad Carter, Santi Cassisi, Bruno Vaz Castilho, Norbert Christlieb, Ryan Cooke, Stefano Covino, Gabriele Cremonese, Katia Cunha, Andre R. da Silva, Valerio D'Elia, Annalisa De Cia, Gayandhi De Silva, Marcos Diaz, Paolo Di Marcantonio, Heitor Ernandes, Alan Fitzsimmons, Mariagrazia Franchini, Boris T. Gansicke, Matteo Genoni, Riano E. Giribaldi, Andrea Grazian, Camilla Juul Hansen, Fiorangela La Forgia, Monica Lazzarin, Wagner Marcolino, Marcella Marconi, Alessandra Migliorini, Pasquier Noterdaeme, Claudio Pereira, Bogumil Pilecki, Andreas Quirrenbach, Sofia Randich, Silvia Rossi, Rodolfo Smiljanic, Colin Snodgrass, Julian Stuermer, Andrea Trost, Eros Vanzella, Paolo Ventura, Duncan Wright, Tayyaba Zafar
Summary: This paper introduces the scientific motivations for the development of the Cassegrain U-Band Efficient Spectrograph (CUBES) for the Very Large Telescope. It covers a wide range of astronomical topics where current ground-based spectrographs are limited. Each topic's background is presented, and specific technical requirements for the instrument design are identified. The CUBES design aims to greatly improve the efficiency of astronomical spectroscopy over a specific wavelength range, and its predicted performance is compared to existing facilities.
EXPERIMENTAL ASTRONOMY
(2023)
Article
Astronomy & Astrophysics
Daniela Carollo, Norbert Christlieb, Patricia B. Tissera, Emanuel Sillero
Summary: We studied the chemodynamical properties of very metal-poor (VMP) stars from the Hamburg/ESO survey matched with Gaia EDR3. By analyzing the phase space using the three integrals of motion, we found VMP stars with disk kinematics and extremely metal-poor stars. We also identified halo stars bound to the gravitational potential of the progenitor halo. Comparison with simulated galaxies suggests that VMP stars with disk kinematics can form through accretion from early satellites and in situ formation.
ASTROPHYSICAL JOURNAL
(2023)
Proceedings Paper
Instruments & Instrumentation
S. Cristiani, J. M. Alcala, S. H. P. Alencar, S. A. Balashev, N. Bastian, B. Barbuy, U. Battino, A. Calcines, G. Calderone, P. Cambianica, R. Carini, B. Carter, S. Cassisi, B. V. Castilho, G. Cescutti, N. Christlieb, R. Cirami, I. Coretti, R. Cooke, S. Covino, G. Cremonese, K. Cunha, G. Cupani, A. R. da Silva, V. De Caprio, A. De Cia, H. Dekker, V. D'Elia, G. De Silva, M. Diaz, P. Di Marcantonio, D. D'Auria, V. D'Odorico, A. Fitzsimmons, H. Ernandes, C. Evans, M. Franchini, M. Genoni, B. Gansicke, R. E. Giribaldi, C. Gneiding, A. Grazian, C. J. Hansen, F. La Forgia, M. Landoni, M. Lazzarin, D. Lunney, W. Maciel, W. Marcolino, M. Marconi, A. Migliorini, C. Miller, P. Noterdaeme, C. Opitom, G. Pariani, B. Pilecki, S. Piranomonte, A. Quirrenbach, E. M. A. Redaelli, C. B. Pereira, S. Randich, S. Rossi, R. Sanchez-Janssen, W. Seifert, R. Smiljanic, C. Snodgrass, I. Stilz, J. Stuermer, E. Vanzella, P. Ventura, O. Verducci, C. Waring, S. Watson, M. Wells, D. Wright, T. Zafar, A. Zanutta
Summary: In the era of Extremely Large Telescopes, current 8-10m facilities are expected to remain competitive in ground-UV wavelengths. The Cassegrain U-Band Efficient Spectrograph (CUBES) is designed to provide high-efficiency observations in the near UV range and offer new possibilities in various fields of astrophysics. The project has entered the detailed design and construction phase, with first science operations planned for 2028.
GROUND-BASED AND AIRBORNE INSTRUMENTATION FOR ASTRONOMY IX
(2022)
Proceedings Paper
Instruments & Instrumentation
Roelof S. de Jong, Olga Bellido-Tirado, Joar G. Brynnel, Aida Ezzati Amini, Steffen Frey, Christine Fuesslein, Miklos Gaebler, Domenico Giannone, Diana Johl, Silke Kuba, Ulrike Lemke, Genoveva Micheva, Allar Saviauk, Matthias Steinmetz, Jakob C. Walcher, Roland Winkler, Karin Lind, Jonathan Loveday, Sofia Feltzing, Richard McMahon, Vincenzo Mainieri, Jean-Francois Pirard, Thomas Bensby, Maria Bergemann, Cristina Chiappini, Norbert Christlieb, Maria-Rosa L. Cioni, Johan Comparat, Simon Driver, Isobel Hook, Mike Irwin, Jean-Paul Kneib, Jochen Liske, Andrea Merloni, Ivan Minchev, Johan Richard, Else Starkenburg, Mark Sullivan, Clare Worley, Wolfgang Gaessler, Florence Laurent, Johan Pragt, Alban Remillieux, Florian Rothmaier, Scott Smedley, Ingo Stilz, Nicholas Walton, David M. Alexander, Ross Church, Scott Croom, Luke J. Davies, Caroline Heneka, Nikolay Kacharov, Joerg Knoche, Georges Kordopatis, Mirko Krumpe, Sarah Martell, Peder Norberg, Ingrid Pelisoli, Sanjib Sharma, Jesper Storm, Elmo Tempel
Summary: 4MOST is a new high-multiplex, wide-field spectroscopic survey facility being constructed for ESO's 4m-VISTA telescope in Chile. It has a large field of view and a high multiplex fibre positioner, enabling both high-resolution and low-resolution optical spectroscopy.
GROUND-BASED AND AIRBORNE INSTRUMENTATION FOR ASTRONOMY IX
(2022)
Article
Astronomy & Astrophysics
Guilherme Limberg, Silvia Rossi, Timothy C. Beers, Helio D. Perottoni, Angeles Perez-Villegas, Rafael M. Santucci, Yuri Abuchaim, Vinicius M. Placco, Young Sun Lee, Norbert Christlieb, John E. Norris, Michael S. Bessell, Sean G. Ryan, Ronald Wilhelm, Jaehyon Rhee, Anna Frebel
Summary: The study analyzes the dynamical properties of around 1500 very metal-poor halo stars, identifying 38 dynamically tagged groups (DTGs), some of which are associated with known substructures like Gaia-Sausage/Enceladus, Sequoia, Helmi Stream, and Thamnos, as well as 10 new DTGs with retrograde orbits. Connections between DTGs and r-process-enhanced stars are investigated, suggesting that ultra-faint and/or dwarf spheroidal galaxies may have been birth environments for these stars disrupted by the Milky Way.
ASTROPHYSICAL JOURNAL
(2021)