Article
Astronomy & Astrophysics
R. K. Alexander, F. Vincenzo, A. P. Ji, H. Richstein, C. J. Jordan, B. K. Gibson
Summary: Ultra-faint dwarf galaxies (UFDs) are metal-poor galaxies without gas, and understanding the chemical abundance dispersion in these extreme environments can provide insights into the first generations of stars. The i-getool model is applied to two UFDs, Carina II and Reticulum II, to study their chemical evolution. The model considers the Monte Carlo sampling of the initial mass function and the chemical enrichment of supernova bubbles in the interstellar medium. The model successfully predicts the abundance patterns of alpha- and odd-Z elements, but underestimates carbon and titanium abundances due to the uncertainty in stellar nucleosynthesis yields. The model also suggests galactic outflows driven by supernova feedback, which quench star formation activity.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
R. Culpan, I Pelisoli, S. Geier
Summary: Blue horizontal-branch stars are old objects that can be used as markers in studies of the Galactic structure and formation history. By cross-matching Gaia data with existing reference catalogues, selection criteria were defined to create a clean sky catalogue of blue horizontal-branch stars. The methods were verified and applied to the latest Gaia release, resulting in a catalogue of 57,377 blue horizontal-branch stars.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
L. J. A. Scott, R. Hirschi, C. Georgy, W. D. Arnett, C. Meakin, E. A. Kaiser, S. Ekstrom, N. Yusof
Summary: The study on the application of the entrainment law in 1D models reveals that the impact of mass and time on boundary penetrability varies, with the chemical gradient having a greater influence on time.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
S. Kamann, S. Saracino, N. Bastian, S. Gossage, C. Usher, D. Baade, I Cabrera-Ziri, S. E. de Mink, S. Ekstrom, C. Georgy, M. Hilker, S. S. Larsen, D. Mackey, F. Niederhofer, I Platais, D. Yong
Summary: Young star clusters are important for studying the effects of stellar rotation on stellar evolution. In a study of the star cluster NGC 1850, researchers measured the rotational velocities of stars and found a correlation between rotation and color. The findings impact our understanding of young massive clusters and provide new observational constraints for stellar evolutionary models.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
C. T. Nguyen, G. Costa, L. Girardi, G. Volpato, A. Bressan, Y. Chen, P. Marigo, X. Fu, P. Goudfrooij
Summary: This article presents a new collection of stellar evolutionary tracks and isochrones for rotating low- and intermediate-mass stars. The collection includes various improvements and updates, covering different phases of stellar evolution, and provides data for different photometric systems. This collection is valuable for conducting stellar population studies.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
K. Inight, Boris T. Gansicke, E. Breedt, T. R. Marsh, A. F. Pala, R. Raddi
Summary: Close white dwarf binaries play a crucial role in various astrophysical phenomena, but limited and biased observational samples hinder in-depth understanding of their evolutionary pathways.
The goal is to establish a representative volume-limited sample and investigate the evolution of these systems in observational properties.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Santana Mansfield, Pavel Kroupa
Summary: By conducting theoretical stellar modeling at low metallicities, it was discovered that the transition of stars from partially to fully convective can lead to the Gaia M-dwarf gap phenomenon.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
Santana Mansfield, Pavel Kroupa
Summary: Low-mass M-dwarf models exhibit fluctuation in luminosity and temperature due to the convective kissing instability, leading to a gap in the main sequence that is also observed in the Gaia data. The amplitude and intensity of the instability are found to decrease with increasing convective overshooting but are sustained in the presence of semi-convection. Surface abundances of various elements change over time, albeit with small relative changes. The M-dwarf gap is reproduced in color-magnitude diagrams, showing a large indent into the blueward edge of the main sequence. The width of the main sequence decreases over time, along with changes in the parallel offset and relative angle between the upper and lower parts of the main sequence, and the mass-magnitude relation. Potential age-dating methods for single stars and stellar populations are discussed.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Daniel Lazarz, Renbin Yan, Ronald Wilhelm, Yanping Chen, Lewis Hill, Jon A. Holtzman, Julie Imig, Claudia Maraston, Szabolcs Meszaros, Guy S. Stringfellow, Daniel Thomas, Timothy C. Beers, Dmitry Bizyaev, Niv Drory, Richard R. Lane, Christian Nitschelm
Summary: This study presents a stellar parameter catalog accompanying the MaStar Stellar Library, providing empirical, medium-resolution stellar spectra. By fitting spectra, possible deficiencies in current theoretical model spectra are revealed, highlighting the potential of MaStar spectra to improve models.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
K. J. Nikitha, S. Vig, S. K. Ghosh
Summary: By studying NGC 5053, a globular cluster, using UV images obtained from AstroSat's UV instrument, we were able to locate and identify the stellar populations, confirming that the BSS population of this cluster likely originated from collisions. We characterized the cluster properties using BaSTI-IAC isochrones and found the best fit model with alpha-enhancement, Y=0.247, [Fe/H]=-1.9, and age=12.5+/-2.0 Gyr.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Don A. VandenBerg, Luca Casagrande, Bengt Edvardsson
Summary: This study compares stellar models for -2.5 <= [Fe/H] <=-0.5 that have been computed for variations in the C:N:O abundance ratio with observations of globular clusters using HST Wide Field Camera 3. The results show that the isochrones for [O/Fe] = 0.6 and [m/Fe] = 0.4, as well as other alpha elements, generally reproduce the main features of the observed colour-magnitude diagrams, but have difficulty explaining the blue and red giants. Allowing for moderate He abundance variations improves the fits to the observations.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Valeriya Korol, Vasily Belokurov, Silvia Toonen
Summary: The study detects unresolved binary stars by measuring the wobble of their orbits and finds a deep gap around 1 astronomical unit. Models suggest a significant change in the distribution of double white dwarfs in this gap.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
K. Inight, B. T. Gansicke, D. Blondel, D. Boyd, R. P. Ashley, C. Knigge, K. S. Long, T. R. Marsh, J. McCleery, S. Scaringi, D. Steeghs, J. R. Thorstensen, T. Vanmunster, P. J. Wheatley
Summary: ASAS J071404+7004.3, a bright and nearby nova-like cataclysmic variable, was recently identified through various observations. Its period and mass transfer rate were determined, and rapidly changing winds from the accretion disk were found, with emission lines potentially originating from these winds. The variability of cataclysmic variables in the Gaia Hertzsprung-Russell diagram was also discussed.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Elias K. Oakes, Taylor J. Hoyt, Wendy L. Freedman, Barry F. Madore, Quang H. Tran, William Cerny, Rachael L. Beaton, Mark Seibert
Summary: In this study, the authors determined the distance modulus of the Fornax dwarf spheroidal galaxy using ground-based imaging and proper motion observations. They used multiple methods to calibrate and validate the results, and obtained a distance of 143 +/- 3 kpc for the galaxy.
ASTROPHYSICAL JOURNAL
(2022)
Article
Astronomy & Astrophysics
E. Leitinger, H. Baumgardt, I Cabrera-Ziri, M. Hilker, E. Pancino
Summary: This paper presents a comprehensive analysis of multiple stellar populations in 28 Galactic globular clusters. The results show that young clusters can have either enriched or primordial populations, or no concentrated population. Old clusters exhibit fully mixed populations as expected. The diversity in these results highlights the need for additional theories to explain the wide variety of initial conditions found. The paper also investigates the correlation between the enriched star fraction and the initial mass of a cluster.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
V. Aguirre Borsen-Koch, J. L. Rorsted, A. B. Justesen, A. Stokholm, K. Verma, M. L. Winther, E. Knudstrup, K. B. Nielsen, C. Sahlholdt, J. R. Larsen, S. Cassisi, A. M. Serenelli, L. Casagrande, J. Christensen-Dalsgaard, G. R. Davies, J. W. Ferguson, M. N. Lund, A. Weiss, T. R. White
Summary: We introduce BASTA, a public version of the Bayesian Stellar Algorithm, an open-source code written in Python. It is designed to determine stellar properties based on astrophysical observables and can robustly combine large datasets including asteroseismology, spectroscopy, photometry, and astrometry. BASTA is the most complete analysis pipeline available for oscillating main-sequence, subgiant, and red giant stars.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Ranjan Kumar, Ananta C. Pradhan, M. Parthasarathy, Sonika Piridi, Santi Cassisi, Devendra K. Ojha, Abhisek Mohapatra, Jayant Murthy
Summary: This study investigated UV bright sources in the Galactic globular cluster NGC 4590 using the Ultraviolet Imaging Telescope aboard the AstroSat satellite. Different evolutionary stages of stars were identified and characterized using UV-optical color-magnitude diagrams. The physical properties of these hot stars, such as temperature, gravity, luminosity, and radius, were estimated using stellar atmosphere models. The study also found that NGC 4590 is one of the youngest clusters among dynamically intermediate age GGCs.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Carmela Lardo, Maurizio Salaris, Santi Cassisi, Nate Bastian
Summary: Stars in massive star clusters show intrinsic variations that are difficult to explain. Recent observations have revealed the global properties of these clusters in great detail using chromosome maps. Traditionally, the first population stars were considered to have uniform chemical composition, but recent studies have shown that they can have intrinsic metallicity variations. However, there are conflicting results regarding the metal abundance in two clusters. This study validates these results and confirms the presence of metallicity spreads among first population stars, further supporting the existence of unexpected variations in most star clusters.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
P. Massana, T. Ruiz-Lara, N. E. D. Noel, C. Gallart, D. L. Nidever, Y. Choi, J. D. Sakowska, G. Besla, K. A. G. Olsen, M. Monelli, A. Dorta, G. S. Stringfellow, S. Cassisi, E. J. Bernard, D. Zaritsky, M. -R. L. Cioni, A. Monachesi, R. P. Van der Marel, T. J. L. De Boer, A. R. Walker
Summary: We used the SMASH survey to quantitatively derive the star formation history of the Small Magellanic Cloud (SMC) and found five distinctive peaks of star formation in the last 3.5 billion years. We compared the star formation history of the SMC with that of the Large Magellanic Cloud (LMC) and found clear synchronicity. Tidal interactions between the two galaxies have played an important role in their evolution for the past 3.5 billion years.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
O. L. Creevey, R. Sordo, F. Pailler, Y. Fremat, U. Heiter, F. Thevenin, R. Andrae, M. Fouesneau, A. Lobel, C. A. L. Bailer-Jones, D. Garabato, I. Bellas-Velidis, E. Brugaletta, A. Lorca, C. Ordenovic, P. A. Palicio, L. M. Sarro, L. Delchambre, R. Drimmel, J. Rybizki, G. Torralba Elipe, A. J. Korn, A. Recio-Blanco, M. S. Schultheis, F. De Angeli, P. Montegri, A. Abreu Aramburu, S. Accart, M. A. Alvarez, J. Bakker, N. Brouillet, A. Burlacu, R. Carballo, L. Casamiquela, A. Chiavassa, G. Contursi, W. J. Cooper, C. Dafonte, A. Dapergolas, P. de Laverny, T. E. Dharmawardena, B. Edvardsson, Y. Le Fustec, P. Garcia-Lario, M. Garcia-Torres, A. Gomez, I. Gonzalez-Santamaria, D. Hatzidimitriou, A. Jean-Antoine Piccolo, M. Kontiza, G. Kordopatis, A. C. Lanzafame, Y. Lebreton, E. L. Licata, H. E. P. Lindstrom, E. Livanou, A. Magdaleno Romeo, M. Manteiga, F. Marocco, D. J. Marshall, N. Mary, C. Nicolas, L. Pallas-Quintela, C. Panem, B. Pichon, E. Poggio, F. Riclet, C. Robin, R. Santovena, A. Silvelo, I. Slezak, R. L. Smart, C. Soubiran, M. Suveges, A. Ulla, E. Utrilla, A. Vallenari, H. Zhao, J. Zorec, D. Barrado, A. Bijaoui, J. -C. Bouret, R. Blomme, I. Brott, S. Cassisi, O. Kochukhov, C. Martayan, D. Shulyak, J. Silvester
Summary: Gaia Data Release 3 provides a wealth of new data products, including astrophysical parameters derived by the Astrophysical parameters inference system (Apsis). This paper describes the overall content of the astrophysical parameters in Gaia DR3 and their generation process. The parameters include source classification, interstellar medium characterization, redshift calculations, and various stellar spectroscopic and evolutionary parameters, making it the most extensive and homogeneous database of astrophysical parameters to date. This catalogue will remain a key reference for the next four years, independent of other ground- and space-based data.
ASTRONOMY & ASTROPHYSICS
(2023)
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
C. Lardo, M. Salaris, S. Cassisi, N. Bastian, A. Mucciarelli, I. Cabrera-Ziri, E. Dalessandro
Summary: Photometric investigations have discovered internal metallicity variations in Galactic globular clusters, contradicting previous beliefs of homogeneous initial chemical composition. However, spectroscopic evidence has not fully supported this finding. In this study, a high-resolution re-analysis of stars in the NGC 2808 cluster revealed a range of iron abundances, indicating intrinsic abundance spreads among first-population stars. The variations in Si, Ca, Ti, and Ni abundances are correlated with iron variations, and the total abundance spreads for all elements are consistent, suggesting the contribution of massive stars as supernovae to gas self-enrichment during star formation.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
Jianxing Chen, Francesco R. Ferraro, Maurizio Salaris, Mario Cadelano, Barbara Lanzoni, Cristina Pallanca, Leandro G. Althaus, Santi Cassisi
Summary: Recently, a new class of slowly cooling white dwarfs (WDs) has been discovered in two globular clusters, M13 and NGC 6752. These WDs exhibit a horizontal branch morphology with an extended blue tail, and their cooling rate is reduced due to stable thermonuclear hydrogen burning. This suggests that they originate from stars on the blue tail of the horizontal branch, bypassing the asymptotic giant branch phase. By analyzing deep photometric data obtained from the Hubble Space Telescope, a comparison between M5 and M3, two Galactic globular clusters with similar HB morphology, confirms the presence of a direct causal connection between the slow cooling WD phenomenon and the horizontal branch morphology of the host stellar cluster.
ASTROPHYSICAL JOURNAL
(2023)
Article
Astronomy & Astrophysics
Mattia Libralato, Enrico Vesperini, Andrea Bellini, Antonino P. Milone, Roeland P. van der Marel, Giampaolo Piotto, Jay Anderson, Antonio Aparicio, Beatriz Barbuy, Luigi R. Bedin, Thomas M. Brown, Santi Cassisi, Domenico Nardiello, Ata Sarajedini, Michele Scalco
Summary: Our understanding of the kinematic properties of multiple stellar populations (mPOPs) in Galactic globular clusters (GCs) is limited. We analyzed 56 GCs using high-precision proper motions computed with Hubble Space Telescope data. We found that 1G stars are generally kinematically isotropic, while 2G stars are isotropic at the center and become radially anisotropic before the half-light radius. The radial anisotropy is induced by a lower tangential velocity dispersion of 2G stars with respect to the 1G population.
ASTROPHYSICAL JOURNAL
(2023)
Article
Astronomy & Astrophysics
Mirko Simunovic, Thomas H. H. Puzia, Bryan Miller, Eleazar R. R. Carrasco, Aaron Dotter, Santi Cassisi, Stephanie Monty, Peter Stetson
Summary: This study presents a photometric analysis of globular cluster 47 Tuc (NGC 104) using near-IR imaging data. The analysis combines near-IR photometry from the GeMS/ GSAOI Galactic Globular Cluster Survey with optical photometry from the Hubble Space Telescope, resulting in a high-quality color-magnitude diagram. Bayesian analysis using the BASE-9 software provides probability distributions and precise estimates for the cluster's age, distance, and extinction parameters. The estimated age of 47 Tuc is 12.42(-0.05)(+0.05)+/- 0.08 Gyr, and the true distance modulus is (m-M)0= 13.250-(+ 0.003)(-0.003) +/- 0.028 mag, consistent with previous studies.
ASTROPHYSICAL JOURNAL
(2023)
Article
Astronomy & Astrophysics
M. Di Criscienzo, S. Leccia, V. Braga, I. Musella, G. Bono, M. Dall'Ora, G. Fiorentino, M. Marconi, R. Molinaro, V. Ripepi, K. Carrell, Y. Choi, S. Savarese, L. Schreiber
Summary: This investigation focuses on the LSST Survey Strategy Optimization process and the development of a new tool called PulsationStarRecovery. It demonstrates the importance of excellent recovery in understanding the potential of LSST in using pulsating stars as stellar tracers and distance indicators. The study also shows the difference in recovery based on distance and variable-star type.
ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES
(2023)
Article
Astronomy & Astrophysics
Ranjan Kumar, Ananta C. Pradhan, Snehalata Sahu, Annapurni Subramaniam, Sonika Piridi, Santi Cassisi, Devendra K. Ojha
Summary: This study presents a study of hot stellar populations in globular clusters M3 and M13 using far-ultraviolet (FUV) observations. Based on the FUV-optical color-magnitude diagrams, the sources are classified into different types of stars. The comparison of synthetic and observed colors suggests that the mass-loss and helium spread have an effect on the different distributions of stars in the clusters.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
M. Griggio, M. Salaris, D. Nardiello, L. R. Bedin, S. Cassisi, J. Anderson
Summary: We used new observations from the Canada-France-Hawaii Telescope to study the white dwarf cooling sequence of the open cluster M37. We found an extended main-sequence turn-off and a spread of initial chemical composition in this cluster. By calculating proper motions, we were able to separate cluster members from field stars and isolate a sample of the white dwarf population of M37. The comparison with theoretical models helped us exclude the age-spread scenario as the main reason for the extended turn-off seen in the cluster's color-magnitude diagram.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
M. Griggio, M. Salaris, L. R. Bedin, S. Cassisi
Summary: Our study of the unevolved main sequence of the open cluster M38 using Gaia and Sloan photometry reveals that the observed colour spreads can be explained by differential reddening and the presence of unresolved binaries, without the need for a spread of initial chemical composition.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Sam M. Ward, Stephen Thorp, Kaisey S. Mandel, Suhail Dhawan, David O. Jones, Kirsty Taggart, Ryan J. Foley, Gautham Narayan, Kenneth C. Chambers, David A. Coulter, Kyle W. Davis, Thomas de Boer, Kaylee de Soto, Nicholas Earl, Alex Gagliano, Hua Gao, Jens Hjorth, Mark E. Huber, Luca Izzo, Danial Langeroodi, Eugene A. Magnier, Peter McGill, Armin Rest, Cesar Rojas-Bravo, Radoslaw Wojtak, Young Supernova Experiment
Summary: This paper analyzes the Young Supernova Experiment data on the Ia-type supernova siblings of SN 2021hpr in NGC 3147, proposing a Bayesian framework for analyzing supernova siblings and obtaining robust estimates by marginalizing intrinsic scatter parameters. The study also explores the impact of siblings on dust parameters.
ASTROPHYSICAL JOURNAL
(2023)