المؤلفون: Peter B. Stetson, Massimo Marengo, E. Valenti, C. K. Gilligan, J. P. Mullen, Jillian R. Neeley, P. M. Marrese, Matteo Monelli, George W. Preston, I. Ferraro, H. Lala, Maurizio Salaris, Vittorio F. Braga, Brian Chaboyer, R. da Silva, Giuseppe Bono, Eva K. Grebel, Z. Prudil, Manuela Zoccali, Giuliana Fiorentino, Mario Nonino, S. Marinoni, G. Altavilla, Christopher Sneden, Noriyuki Matsunaga, G. Iannicola, J. Crestani, M. Fabrizio, B. Lemasle, D. Magurno, C. E. Martínez-Vázquez, Massimo Dall'Ora, Frédéric Thévenin

المساهمون: Joseph Louis LAGRANGE (LAGRANGE), Université Côte d'Azur (UCA)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), COMUE Université Côte d'Azur (2015 - 2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015 - 2019) (COMUE UCA)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015 - 2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)

المصدر: The Astrophysical Journal
The Astrophysical Journal, American Astronomical Society, 2021, 919 (2), pp.118. ⟨10.3847/1538-4357/ac1115⟩

مصطلحات موضوعية: spectroscopy, Milky Way stellar halo, RR Lyrae variable stars, Metallicity, Population, FOS: Physical sciences, Astrophysics, RR Lyrae variable, 01 natural sciences, Standard deviation, Spectral line, 0103 physical sciences, education, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), ComputingMilieux_MISCELLANEOUS, Physics, education.field_of_study, Settore FIS/05, 010308 nuclear & particles physics, Sigma, Astronomy and Astrophysics, Amplitude, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Globular cluster, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]

الوصف: We discuss the largest and most homogeneous spectroscopic dataset of field RR Lyrae variables (RRLs) available to date. We estimated abundances using both high-resolution and low-resolution ({\Delta S} method) spectra for fundamental (RRab) and first overtone (RRc) RRLs. The iron abundances for 7,941 RRLs were supplemented with similar literature estimates available, ending up with 9,015 RRLs (6,150 RRab, 2,865 RRc). The metallicity distribution shows a mean value of = -1.51\pm0.01, and {\sigma}(standard deviation)= 0.41 dex with a long metal-poor tail approaching [Fe/H] = -3 and a sharp metal-rich tail approaching solar iron abundance. The RRab variables are more metal-rich (ab = -1.48\pm0.01, {\sigma} = 0.41 dex) than RRc variables (c = -1.58\pm0.01, {\sigma} = 0.40 dex). The relative fraction of RRab variables in the Bailey diagram (visual amplitude vs period) located along the short-period (more metal-rich) and the long-period (more metal-poor) sequences are 80% and 20\%, while RRc variables display an opposite trend, namely 30\% and 70\%. We found that the pulsation period of both RRab and RRc variables steadily decreases when moving from the metal-poor to the metal-rich regime. The visual amplitude shows the same trend, but RRc amplitudes are almost two times more sensitive than RRab amplitudes to metallicity. We also investigated the dependence of the population ratio (Nc/Ntot) of field RRLs on the metallicity and we found that the distribution is more complex than in globular clusters. The population ratio steadily increases from ~0.25 to ~0.36 in the metal-poor regime, it decreases from ~0.36 to ~0.18 for -1.8 < [Fe/H] < -0.9 and it increases to a value of ~0.3 approaching solar iron abundance.
Comment: 22 pages, 13 figures, 3 tables. Accepted for publication in ApJ

وصف الملف: application/pdf

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::4a18cb8f54f0a75256d9d493a19b8277Test
https://nrc-publications.canada.ca/eng/view/object/?id=333fbe61-a23d-4235-a8ab-3fce6befb941Test

المؤلفون: Alan Alves-Brito, J. P. Mullen, H. Lala, Jesper Storm, P. M. Marrese, Peter B. Stetson, Massimo Dall'Ora, J. Neeley, M. Marengo, Manuela Zoccali, Brian Chaboyer, J. Crestani, A. J. Koch-Hansen, C. E. Martínez-Vázquez, Mario Nonino, F. Thévenin, Noriyuki Matsunaga, M. Monelli, M. Fabrizio, V. F. Braga, Maurizio Salaris, Bertrand Lemasle, Christopher Sneden, Elena Valenti, R. da Silva, S. Marinoni, Z. Prudil, G. Altavilla, I. Ferraro, Giuliana Fiorentino, Giuseppe Bono, George W. Preston, G. Iannicola, C. K. Gilligan, Eva K. Grebel, Valentina D'Orazi

المساهمون: Joseph Louis LAGRANGE (LAGRANGE), Université Côte d'Azur (UCA)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)

المصدر: The Astrophysical Journal
The Astrophysical Journal, American Astronomical Society, 2021, 914 (1), pp.10. ⟨10.3847/1538-4357/abfa23⟩

مصطلحات موضوعية: Physics, spectroscopy, Milky Way stellar halo, Field (physics), RR Lyrae variable stars, Settore FIS/05, Astronomy and Astrophysics, Astrophysics, RR Lyrae variable, Astrophysics - Astrophysics of Galaxies, 01 natural sciences, 010309 optics, Astrophysics - Solar and Stellar Astrophysics, 13. Climate action, Space and Planetary Science, 0103 physical sciences, high resolution spectroscopy, Spectroscopy, pulsating variable stars, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], 010303 astronomy & astrophysics, QC, ComputingMilieux_MISCELLANEOUS, QB

الوصف: We provide the largest and most homogeneous sample of $\alpha$-element (Mg, Ca, Ti) and iron abundances for field RR Lyrae (RRLs, 162 variables) by using high-resolution spectra. The current measurements were complemented with similar abundances available in the literature for 46 field RRLs brought to our metallicity scale. We ended up with a sample of old (t$\ge$ 10 Gyr), low-mass stellar tracers (208 RRLs: 169 fundamental, 38 first overtone, 1 mixed mode) covering three dex in iron abundance (-3.00$\le$[Fe/H]$\le$0.24). We found that field RRLs are $\sim$0.3 dex more $\alpha$-poor than typical Halo tracers in the metal-rich regime, ([Fe/H]$\ge$-1.2) while in the metal-poor regime ([Fe/H]$\le$-2.2) they seem to be on average $\sim$0.1 dex more $\alpha$-enhanced. This is the first time that the depletion in $\alpha$-elements for solar iron abundances is detected on the basis of a large, homogeneous and coeval sample of old stellar tracers. Interestingly, we also detected a close similarity in the [$\alpha$/Fe] trend between $\alpha$-poor, metal-rich RRLs and red giants (RGs) in the Sagittarius dwarf galaxy as well as between $\alpha$-enhanced, metal-poor RRLs and RGs in ultra faint dwarf galaxies. These results are supported by similar elemental abundances for 46 field Horizontal Branch (HB) stars. These stars share with RRLs the same evolutionary phase and the same progenitors. This evidence further supports the key role that old stellar tracers play in constraining the early chemical enrichment of the Halo and, in particular, in investigating the impact that dwarf galaxies have had in the mass assembly of the Galaxy.

وصف الملف: application/pdf

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::a1025e051de8aced2bc1bfa43c49d707Test
https://hal.archives-ouvertes.fr/hal-03375259Test

المؤلفون: J. Neeley, C. E. Martínez-Vázquez, J. Crestani, Brian Chaboyer, Massimo Dall'Ora, M. Fabrizio, Giuliana Fiorentino, Massimo Marengo, Frédéric Thévenin, C. K. Gilligan, Giuseppe Bono, J. P. Mullen, Christopher Sneden, M. Monelli, V. F. Braga

المساهمون: Joseph Louis LAGRANGE (LAGRANGE), Université Côte d'Azur (UCA)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)

المصدر: Monthly Notices of the Royal Astronomical Society
Monthly Notices of the Royal Astronomical Society, Oxford University Press (OUP): Policy P-Oxford Open Option A, 2021, 503 (4), pp.4719-4733. ⟨10.1093/mnras/stab857⟩

مصطلحات موضوعية: Physics, Settore FIS/05, 010308 nuclear & particles physics, FOS: Physical sciences, High resolution, Astronomy and Astrophysics, Astrophysics, RR Lyrae variable, Astrophysics - Astrophysics of Galaxies, 01 natural sciences, Spectral line, Stars, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), 0103 physical sciences, High resolution spectra, Southern African Large Telescope, Parallax, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR)

الوصف: Accurate metallicities of RR Lyrae are extremely important in constraining period-luminosity-metallicity relationships (PLZ), particularly in the near-infrared. We analyse 69 high-resolution spectra of Galactic RR Lyrae stars from the Southern African Large Telescope (SALT). We measure metallicities of 58 of these RR Lyrae stars with typical uncertainties of 0.13 dex. All but one RR Lyrae in this sample has accurate ({\sigma}_parallax ~ 10%) parallax from Gaia. Combining these new high resolution spectroscopic abundances with similar determinations from the literature for 93 stars, we present new PLZ relationships in WISE W1 and W2 magnitudes, and the Wesenheit magnitudes W(W1,V-W1) and W(W2,V-W2).
Comment: 16 pages, 13 figures, accepted in MNRAS

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::03474d9b2cc5bb077c17f7352a90ff78Test
https://hal.archives-ouvertes.fr/hal-03375224Test

المؤلفون: I. Ferraro, Laura Inno, P. B. Stetson, H. Lala, G. Iannicola, G. Altavilla, V. F. Braga, Christopher Sneden, M. Zoccali, Giuseppe Bono, George W. Preston, J. Crestani, Noriyuki Matsunaga, S. Marinoni, M. Fabrizio, C. K. Gilligan, Brian Chaboyer, Giuliana Fiorentino, J. Neeley, J. P. Mullen, M. Marengo, R. da Silva, Eva K. Grebel, Valentina D'Orazi, Jesper Storm, Z. Prudil, Elena Valenti, A. R. Walker, F. Thévenin, Mario Nonino, C. E. Martínez-Vázquez, Alan Alves-Brito, Massimo Dall'Ora, B. Lemasle, M. Monelli, P. M. Marrese

المساهمون: Joseph Louis LAGRANGE (LAGRANGE), Université Côte d'Azur (UCA)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)

المصدر: The Astrophysical Journal
The Astrophysical Journal, American Astronomical Society, 2021, 908 (1), pp.20. ⟨10.3847/1538-4357/abd183⟩

مصطلحات موضوعية: Physics, Milky Way stellar halo, Field (physics), RR Lyrae variable stars, 010308 nuclear & particles physics, Calibration (statistics), Settore FIS/05, Metallicity, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, RR Lyrae variable, Astrophysics - Astrophysics of Galaxies, 01 natural sciences, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), High resolution spectroscopy, 0103 physical sciences, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), ComputingMilieux_MISCELLANEOUS

الوصف: We performed the largest and most homogeneous spectroscopic survey of field RR Lyraes (RRLs). We secured $\approx$6,300 high resolution (HR, R$\sim$35,000) spectra for 143 RRLs (111 fundamental, RRab; 32 first overtone, RRc). The atmospheric parameters were estimated by using the traditional approach and the iron abundances were measured by using an LTE line analysis. The resulting iron distribution shows a well defined metal-rich tail approaching solar iron abundance. This suggests that field RRLs experienced a complex chemical enrichment in the early halo formation. We used these data to develop a new calibration of the $\Delta$S method. This diagnostic, based on the equivalent widths of CaII K and three Balmer (H$_{\delta,\gamma,\beta}$) lines, traces the metallicity of RRLs. For the first time the new empirical calibration: i) includes spectra collected over the entire pulsation cycle; ii) includes RRc variables; iii) relies on spectroscopic calibrators covering more than three dex in iron abundance; iv) provides independent calibrations based on one/two/three Balmer lines. The new calibrations were applied to both SEGUE-SDSS and degraded HR spectra totalling 6,451 low resolution (LR, R$\sim$2,000) spectra for 5,001 RRLs (3,439 RRab, 1,562 RRc). This resulted in an iron distribution with a median of -1.55$\pm$0.01 and $\sigma$=0.51 dex, in good agreement with literature values. We also found that RRc are 0.10 dex more metal-poor than RRab variables, and have a distribution with a smoother metal-poor tail. This finding supports theoretical prescriptions suggesting a steady decrease in the RRc number when moving from metal-poor to metal-rich stellar environments.
Comment: Accepted by ApJ

وصف الملف: application/pdf

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::86f39ac48861b5a5e65d8c9aab33a66fTest
http://hdl.handle.net/2108/301068Test

المؤلفون: Giuseppe Bono, Valentina D'Orazi, Noriyuki Matsunaga, Y. Wang

المصدر: Proceedings of the International Astronomical Union. 14:540-543

مصطلحات موضوعية: Physics, 010504 meteorology & atmospheric sciences, Astronomy and Astrophysics, Astrophysics, 01 natural sciences, Spectral line, Wavelength, Space and Planetary Science, Globular cluster, 0103 physical sciences, Asymptotic giant branch, Variable star, 010303 astronomy & astrophysics, Chemical composition, Spectrograph, 0105 earth and related environmental sciences, Data reduction

الوصف: Variable stars are good stellar tracers. Among various variables, Miras have long periods and are at the evolutionary phase of asymptotic giant branch. Their low effective temperatures lead to a difficulty to determine their chemical composition that since plenty of molecular bands exist in their spectra which even blocks the identifition of metallic lines. However, molecular features are less common in near-infrared (NIR) compared with other wavelength ranges. Here we take advantage of the high-resolution (R ~ 28, 000) spectra obtained with WINERED, which is a NIR spectrograph covering the wavelength range of 0.91–1.35 μm, to analyze and determine the chemical abundances of three Miras in the Galactic globular cluster 47 Tuc (NGC 104). Steps of data reduction and analysis, as well as part of the preliminary results, are briefly shown.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_________::fda505bb1043c4c4ecc14ef00891c9dcTest
https://doi.org/10.1017/s1743921319006616Test

المؤلفون: François Rigaut, Richard M. McDermid, Giovanni Cresci, Valentina Viotto, Simon C. Ellis, David Brodrick, Guido Agapito, Thierry Fusco, Benoit Neichel, Pierre Haguenauer, Cedric Plantet, Bernardo Salasnich, Matteo Aliverti, Simone Antoniucci, Andrea Balestra, Andrea Baruffolo, Olivier Beltramo-Martin, Maria Bergomi, Andrea Blanco, Marco Bonaglia, Giuseppe Bono, Lorenzo Busoni, Elena Carolo, Simonetta Chinellato, Robert Content, Jesse Cranney, Gayandhi de Silva, Simone Esposito, Daniela Fantinel, Jacopo Farinato, Dionne M. Haynes, Anthony J. Horton, Gaston Gausachs, James Gilbert, Damien Gratadour, Davide Greggio, Marco Gullieuszik, Visa Korkiakoski, Demetrio Magrin, Laura Magrini, Luca Marafatto, Helen McGregor, Trevor Mendel, Stephanie Monty, Fernando Pedichini, Enrico Pinna, Elisa Portaluri, Kalyan K. Radhakrishnan Santhakumari, Roberto Ragazzoni, David Robertson, Christian Schwab, Stefan Ströbele, Elliott Thorn, Annino Vaccarella, Daniele Vassallo, Lew Waller, Frédéric Zamkotsian, Alesso Zanutta, Hao Zhang

المساهمون: Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)

المصدر: Ground-based and Airborne Instrumentation for Astronomy VIII
Ground-based and Airborne Instrumentation for Astronomy VIII, Dec 2020, Online Only, Japan. pp.332, ⟨10.1117/12.2561886⟩

مصطلحات موضوعية: Engineering, [SDU.ASTR.CO]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO], Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, 7. Clean energy, 010309 optics, Integral field spectrograph, Conceptual design, Observatory, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Angular resolution, Adaptive optics, 010303 astronomy & astrophysics, Spectrograph, ComputingMilieux_MISCELLANEOUS, Astrophysics::Galaxy Astrophysics, Very Large Telescope, business.industry, James Webb Space Telescope, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy, [PHYS.ASTR.SR]Physics [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], [SDU.ASTR.IM]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM], Astrophysics::Earth and Planetary Astrophysics, business

الوصف: A consortium of several Australian and European institutes – together with the European Southern Observatory (ESO) – has initiated the design of MAVIS, a Multi-Conjugate Adaptive Optics (MCAO) system for the ground- based 8-m Very Large Telescope (VLT). MAVIS (MCAO-assisted Visible Imager and Spectrograph) will deliver visible images and integral field spectrograph data with 2-3x better angular resolution than the Hubble Space Telescope, making it a powerful complement at visible wavelengths to future facilities like the space-based James Webb Space Telescope and the 30 to 40m-class ground-based telescopes currently under construction, which are all targeting science at near-infrared wavelengths. MAVIS successfully passed its Phase A in May 2020. We present the motivations, requirements, principal design choices, conceptual design, expected performance and an overview of the exciting science enabled by MAVIS.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::8356542fdce52843e00c48eaf3d9e04bTest
https://doi.org/10.1117/12.2561886Test

المؤلفون: R. da Silva, Maurizio Salaris, Giuseppe Bono, George Wallerstein, V. F. Braga, S. Marinoni, Mario Mateo, P. B. Stetson, M. P. Marrese, Giuliana Fiorentino, M. Monelli, Noriyuki Matsunaga, Massimo Dall'Ora, M. Fabrizio

مصطلحات موضوعية: Physics, 010308 nuclear & particles physics, Cepheid variable, Settore FIS/05, Separation (statistics), Astronomy and Astrophysics, Astrophysics, RR Lyrae variable, 01 natural sciences, Omega, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, 0103 physical sciences, 010303 astronomy & astrophysics

الوصف: The separation between RR Lyrae (RRLs) and type II Cepheid (T2Cs) variables based on their period is debated. Both types of variable stars are distance indicators, and we aim to promote the use of T2Cs as distance indicators in synergy with RRLs. We adopted new and existing optical and near-infrared (NIR) photometry ofωCen to investigate several diagnostics (color-magnitude diagram, Bailey diagram, Fourier decomposition of the light curve, and amplitude ratios) for their empirical separation. We found that the classical period threshold at one day is not universal and does not dictate the evolutionary stage: V92 has a period of 1.3 days but is likely to be still in its core helium-burning phase, which is typical of RRLs. We also derived NIR period-luminosity relations and found a distance modulus of 13.65 ± 0.07 (err.) ± 0.01 (σ) mag, in agreement with the recent literature. We also found that RRLs and T2Cs obey the same period-luminosity relations in the NIR. This equivalence provides the opportunity of adopting RRLs+T2Cs as an alternative to classical Cepheids to calibrate the extragalactic distance scale.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::dabf51da5ab9f874b9e07d727317595aTest
http://hdl.handle.net/2108/261605Test

المؤلفون: E. Di Carlo, Matteo Monelli, George W. Preston, S. Marinoni, Bertrand Lemasle, Brian Chaboyer, J. P. Mullen, R. da Silva, Adriano Pietrinferni, J. Crestani, Giuseppe Bono, Marcella Marconi, Laura Inno, Z. Prudil, P. M. Marrese, Scilla Degl'Innocenti, I. Ferraro, Alistair R. Walker, Andrea Kunder, Christopher Sneden, Jillian R. Neeley, G. Altavilla, Frédéric Thévenin, Emanuele Tognelli, Mario Nonino, P. G. Prada Moroni, Massimo Dall'Ora, Giuliana Fiorentino, R. Buonanno, E. Valenti, V. V. Kovtyukh, C. K. Gilligan, Massimo Marengo, G. Iannicola, Peter B. Stetson, C. E. Martínez-Vázquez, Eva K. Grebel, Noriyuki Matsunaga, M. Fabrizio, Vittorio F. Braga

المساهمون: Joseph Louis LAGRANGE (LAGRANGE), Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015 - 2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015 - 2019) (COMUE UCA)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015 - 2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015 - 2019) (COMUE UCA)-Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015 - 2019) (COMUE UCA)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015 - 2019) (COMUE UCA), Université Côte d'Azur (UCA)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)

المصدر: The Astrophysical journal letters
The Astrophysical journal letters, Bristol : IOP Publishing, 2020, 896 (1), pp.L15. ⟨10.3847/2041-8213/ab9538⟩

مصطلحات موضوعية: Radial velocity, RR Lyrae variable stars, 010504 meteorology & atmospheric sciences, Blazhko effect, FOS: Physical sciences, Astrophysics, RR Lyrae variable, 01 natural sciences, Horizontal branch stars, symbols.namesake, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Physics, Settore FIS/05, Balmer series, Astronomy and Astrophysics, Effective temperature, Horizontal branch, Stellar oscillations, Astrophysics - Solar and Stellar Astrophysics, Astrophysics - Astrophysics of Galaxies, Amplitude, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), symbols, Instability strip, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]

الوصف: We collected over 6000 high-resolution spectra of four dozen field RR Lyrae (RRL) variables pulsating either in the fundamental (39 RRab) or in the first overtone (9 RRc) mode. We measured radial velocities (RVs) of four strong metallic and four Balmer lines along the entire pulsational cycle and derived RV amplitudes with accuracies better than 1$-$2~\kmsec. The new amplitudes were combined with literature data for 23~RRab and 3~RRc stars (total sample 74 RRLs) which allowed us to investigate the variation of the Bailey diagram (photometric amplitude versus period) when moving from optical to mid-infrared bands and to re-cast the Bailey diagram in terms of RV amplitudes. We found that RV amplitudes for RRab are minimally affected by nonlinear phenomena (shocks) and multi-periodicity (Blazhko effect). The RV slope ($\log P$--A(V$_r$)) when compared with the visual slope ($\log P$--A($V$)) is shallower and the dispersion, at fixed period, decreases by a factor of two. We constructed homogeneous sets of Horizontal Branch evolutionary models and nonlinear, convective pulsation models of RRLs to constrain the impact of evolutionary effects on their pulsation properties. Evolution causes, on the Bailey diagram based on RV amplitudes, a modest variation in pulsation period and a large dispersion in amplitude. The broad dispersion in period of the Bailey diagram is mainly caused by variation in RRL intrinsic parameters (stellar mass, chemical composition). Empirical evidence indicates that RV amplitudes are an optimal diagnostic for tracing the mean effective temperature across the RRab instability strip.
14 pages, 4 figures, 1 table, Accepted on ApJ Letter

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::06d9903c1edb93790f055c988b080cf8Test
https://hal.archives-ouvertes.fr/hal-02989237Test

المؤلفون: Richard de Grijs, Giuseppe Bono

مصطلحات موضوعية: Physics, Cosmology and Nongalactic Astrophysics (astro-ph.CO), 010504 meteorology & atmospheric sciences, Settore FIS/05, Order (ring theory), Local Group, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Astrophysics - Astrophysics of Galaxies, 01 natural sciences, Virgo Cluster, Luminosity, Moduli, Space and Planetary Science, Globular cluster, Astrophysics of Galaxies (astro-ph.GA), 0103 physical sciences, Coma Cluster, 010303 astronomy & astrophysics, Galaxy cluster, Astrophysics - Cosmology and Nongalactic Astrophysics, 0105 earth and related environmental sciences

الوصف: We consider the published distance moduli to the Fornax and Coma galaxy clusters, with emphasis on the period since 1990. We have carefully homogenized our catalogs of distance moduli onto the distance scale established in the previous papers in this series. We assessed systematic differences associated with the use of specific tracers, and discarded results based on application of the Tully--Fisher relation and of globular cluster and planetary nebula luminosity functions. We recommend `best' weighted relative distance moduli for the Fornax and Coma clusters with respect to the Virgo cluster of $��(m-M)_0^{\rm Fornax - Virgo} = 0.18 \pm 0.28 $ mag and $��(m-M)_0^{\rm Coma - Virgo} = 3.75 \pm 0.23$ mag. The set of weighted mean distance moduli (distances) we derived as most representative of the clusters' distances is, \begin{eqnarray} (m-M)_0^{\rm Fornax} &=& 31.41 \pm 0.15 \mbox{ mag } (D = 19.1^{+1.4}_{-1.2} \mbox{ Mpc) and} \nonumber &=& 31.21 \pm 0.28 \mbox{ mag } (D = 17.5^{+2.4}_{-2.2} \mbox{ Mpc)}; \nonumber \\ (m-M)_0^{\rm Coma} &=& 34.99 \pm 0.38 \mbox{ mag } (D = 99.5^{+19.0}_{-15.9} \mbox{ Mpc) and} \nonumber &=& 34.78 \pm 0.27 \mbox{ mag } (D = 90.4^{+11.9}_{-10.6} \mbox{ Mpc)}, \nonumber \end{eqnarray} where the first value for each cluster is the result of our analysis of the direct distance moduli, while the second modulus is based on distance moduli relative to the Virgo cluster. The absolute and relative distance moduli for both clusters are mutually consistent within the uncertainties; the relative distance moduli yield shorter distances by $\sim$1$��$. Lingering uncertainties in the underlying absolute distance scale appear to have given rise to a systematic uncertainty on the order of 0.20 mag.
15 pages, 3 figures; accepted for publication in ApJS

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::c6f84e69a9708b0728af7067270c0ef4Test

المؤلفون: Bertrand Lemasle, Michael Hanke, Jesper Storm, Eva K. Grebel, Giuseppe Bono

مصطلحات موضوعية: Physics, Settore FIS/05, 010308 nuclear & particles physics, Cepheid variable, Metallicity, Scale of temperature, Flux, FOS: Physical sciences, Astronomy and Astrophysics, Context (language use), Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Effective temperature, 01 natural sciences, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Surface brightness, Small Magellanic Cloud, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Solar and Stellar Astrophysics (astro-ph.SR)

الوصف: Context: The effective temperature is a key parameter governing the properties of a star. For stellar chemistry, it has the strongest impact on the accuracy of the abundances derived. Since Cepheids are pulsating stars, determining their effective temperature is more complicated that in the case of non-variable stars. Aims: We want to provide a new temperature scale for classical Cepheids, with a high precision and full control of the systematics. Methods: Using a data-driven machine learning technique employing observed spectra, and taking great care to accurately phase single-epoch observations, we have tied flux ratios to (label) temperatures derived using the infrared surface brightness method. Results: We identified 143 flux ratios that allow us to determine the effective temperature with a precision of a few K and an accuracy better than 150 K, which is in line with the most accurate temperature measures available to date. The method does not require a normalization of the input spectra and provides homogeneous temperatures for low- and high-resolution spectra, even at the lowest signal-to-noise ratios. Due to the lack of a dataset of sufficient sample size for Small Magellanic Cloud Cepheids, the temperature scale does not extend to Cepheids with [Fe/H] < -0.6 dex but nevertheless provides an exquisite, homogeneous means of characterizing Galactic and Large Magellanic Cloud Cepheids. Conclusions: The temperature scale will be extremely useful in the context of spectroscopic surveys for Milky Way archaeology with the WEAVE and 4MOST spectrographs. It paves the way for highly accurate and precise metallicity estimates, which will allow us to assess the possible metallicity dependence of Cepheids' period-luminosity relations and, in turn, to improve our measurement of the Hubble constant H0.
16 pages, 13 figures, accepted in A&A

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::a638db0dda0fa8c58163d9ed9cb605d3Test