Article
Astronomy & Astrophysics
V. F. Braga, G. Fiorentino, G. Bono, P. B. Stetson, C. E. Martinez-Vazquez, S. Kwak, M. Tantalo, M. Dall'Ora, M. Di Criscienzo, M. Fabrizio, M. Marengo, S. Marinoni, P. M. Marrese, M. Monelli
Summary: We investigated the properties of mixed-mode RR Lyrae variables in the Fornax dwarf spheroidal galaxy and compared them with variables in the Magellanic Clouds and nearby dwarf spheroidals. We found that the ratio of mixed-mode RR Lyrae decreases with metallicity, and Fornax fills a period gap in the Petersen diagram similarly to Small Magellanic Cloud variables. Additionally, a new pulsation diagnostics method reveals that Large Magellanic Cloud variables can be separated into two groups with different evolutionary properties. Our findings suggest that Fornax and Sculptor dwarf spheroidals have undergone different chemical enrichment histories.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Ata Sarajedini, Sevinc Gokmen
Summary: This study compares two relations for calculating the metal abundance of ab-type RR Lyrae variables and determines that knowing only the period of these variables is sufficient to determine the mean metallicity of a globular cluster. Both tested equations accurately reproduce the spectroscopic metal abundance of each cluster, with an accuracy of ±0.28 dex.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Christina K. Gilligan, Brian Chaboyer, Massimo Marengo, Joseph P. Mullen, Giuseppe Bono, Vittorio F. Braga, Juliana Crestani, Massimo Dall'Ora, Giuliana Fiorentino, Matteo Monelli, Jill R. Neeley, Michele Fabrizio, Clara E. Martinez-Vazquez, Frederic Thevenin, Christopher Sneden
Summary: Accurate metallicities of RR Lyrae stars were analyzed in this study using high-resolution spectra from the Southern African Large Telescope. The study presented new period-luminosity-metallicity relationships in WISE W1 and W2 magnitudes, as well as the Wesenheit magnitudes W(W1, V - W1) and W(W2, V- W2) by combining new spectroscopic abundances with literature determinations for 93 stars.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
F. Cusano, M. Moretti, G. Clementini, V Ripepi, M. Marconi, M-R L. Cioni, S. Rubele, A. Garofalo, R. de Grijs, M. A. T. Groenewegen, J. M. Oliveira, S. Subramanian, N-C Sun, J. Th van Loon
Summary: An analysis of around 29000 RR Lyrae stars in the Large Magellanic Cloud revealed important details about individual star distances and the three-dimensional structure of the LMC, providing insights into the distribution and characteristics of these stars in the galaxy.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
M. A. Yepez, A. Arellano Ferro, D. Deras, I Bustos Fierro, S. Muneer, K-P Schroder
Summary: We conducted a photometric study of the globular cluster M14, focusing on the variable stars. By analyzing the light curves of RR Lyrae stars, we determined the cluster's metallicity and average distance. We compared the color-magnitude diagram outlined by the cluster members with theoretical predictions and confirmed the cluster's Oosterhoff type and the distribution of pulsating modes of RR Lyrae stars. We also modeled the mass-loss to analyze the blue tail of the horizontal branch. Our results support that M14 is not of extragalactic origin.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Yoichi Takeda
Summary: The photospheric abundances of C, N, O, and Na in RR Lyr stars were studied to investigate the mixing mechanism in low-mass giant stars. The study confirmed the deficiency in C and enrichment in N in these stars, with the extent of peculiarities increasing with a decrease in metallicity. However, no apparent Na anomaly was observed, contradicting theoretical expectations. Further improvements in the current theory may be necessary.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Ata Sarajedini
Summary: In this study, we analyze archival images of the Wolf-Lundmark-Melotte (WLM) galaxy taken with the Hubble Space Telescope, and identify and characterize RR Lyrae and Cepheid variables. We find that the WLM globular cluster has a lower metallicity than previously thought.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
H. Netzel, L. Molnar, E. Plachy, J. M. Benko
Summary: This article utilizes samples of first-overtone RR Lyrae stars observed by the Kepler telescope during the K2 mission to search for and characterize additional low-amplitude signals. The study discovers new sequences of period ratios and unknown periodicity phenomena.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
G. Clementini, V. Ripepi, A. Garofalo, R. Molinaro, T. Muraveva, S. Leccia, L. Rimoldini, B. Holl, G. Jevardat de Fombelle, P. Sartoretti, O. Marchal, M. Audard, K. Nienartowicz, R. Andrae, M. Marconi, L. Szabados, D. W. Evans, I. Lecoeur-Taibi, N. Mowlavi, I. Musella, L. Eyer
Summary: This study uses RR Lyrae stars as tracers of the oldest stars and as standard candles for distance measurements. The Gaia DR3 publishes a catalogue of these stars, which is validated and characterized using a specific pipeline. The resulting catalogue is the largest and most parameter-rich of all-sky RR Lyrae stars published so far.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
Geza Kovacs, Behrooz Karamiqucham
Summary: The study combines observational data with models to derive average luminosities for RR Lyrae stars and finds that they are in agreement with high accuracy parallax measurements. However, about 10% of the sample shows a curious distance keeping behavior between evolutionary and pulsation models, which may be addressed by increasing reddening excessively.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
Mojgan Aghakhanloo, Nathan Smith, Jennifer Andrews, Knut Olsen, Gurtina Besla, Yumi Choi
Summary: This study investigates the kinematics of LBVs in the LMC and finds that LBVs have a higher velocity dispersion and more runaway stars compared to red supergiants. It suggests that LBVs are preferentially kicked by a companion's supernova explosion. The study also discovers binary companions in some LBVs and identifies a new LBV.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Thomas A. Molnar, Jason L. Sanders, Leigh C. Smith, Vasily Belokurov, Philip Lucas, Dante Minniti
Summary: The study introduces the VIVACE catalogue which extracts variable stars from the VVV infrared survey data through an automated classification pipeline. Utilizing a two-stage hierarchical classifier, the research identifies and classifies variable sources, resulting in a catalogue of approximately 1.4 million likely variable stars with different types and classification probabilities.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
A. Katherina Vivas, Clara E. Martinez-Vazquez, Alistair R. Walker, Vasily Belokurov, Ting S. Li, Denis Erkal
Summary: We report the discovery of 350 pulsating variable stars in four DECam fields covering the Antlia 2 satellite galaxy, including 318 RR Lyrae stars and eight anomalous Cepheids. Reclassification of some previously designated RR Lyrae objects as anomalous Cepheids supports the updated proper motion and pericenter measurements, indicating a lack of tidal disruption in the dwarf galaxy. The presence of bright foreground RR Lyrae stars and distant background variables suggests that Antlia 2 is a large galaxy extending beyond the observed area.
ASTROPHYSICAL JOURNAL
(2022)
Article
Astronomy & Astrophysics
Henryka Netzel, Radoslaw Smolec
Summary: This paper discusses the phenomenon and explanation of additional signals observed in the frequency spectra of first-overtone RR Lyrae stars, and attempts to model these stars with non-radial modes, finding that pulsation masses seem higher than evolutionary masses.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
M. Marconi, R. Molinaro, V Ripepi, S. Leccia, I Musella, G. De Somma, M. Gatto, M. Moretti
Summary: Theoretical light curves in Gaia bands G, G(BP), and G(RP) for RR Lyrae pulsators are derived based on extended non-linear convective models. The effects of chemical composition on the derived parameters and Period-Wesenheit relations are discussed, and theoretical estimates of individual parallaxes for Galactic RR Lyrae in Gaia Data Release 2 are compared with astrometric solutions. A very small offset, consistent with zero, is required to reconcile the predicted distances with Gaia results.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Federica B. Bianco, Zeljko Ivezic, R. Lynne Jones, Melissa L. Graham, Phil Marshall, Abhijit Saha, Michael A. Strauss, Peter Yoachim, Tiago Ribeiro, Timo Anguita, A. E. Bauer, Franz E. Bauer, Eric C. Bellm, Robert D. Blum, William N. Brandt, Sarah Brough, Marcio Catelan, William Clarkson, Andrew J. Connolly, Eric Gawiser, John E. Gizis, Renee Hlozek, Sugata Kaviraj, Charles T. Liu, Michelle Lochner, Ashish A. Mahabal, Rachel Mandelbaum, Peregrine McGehee, Eric H. Jr Jr Neilsen, Knut A. G. Olsen, Hiranya Peiris, Jason Rhodes, Gordon T. Richards, Stephen Ridgway, Megan E. Schwamb, Dan Scolnic, Ohad Shemmer, Colin T. Slater, Anze Slosar, Stephen J. Smartt, Jay Strader, Rachel Street, David E. Trilling, Aprajita Verma, A. K. Vivas, Risa H. Wechsler, Beth Willman
Summary: The Vera C. Rubin Observatory is a ground-based astronomical facility designed to conduct a 10-year optical survey of the Southern Hemisphere sky. It aims to probe dark energy and dark matter, catalog the solar system, explore the transient optical sky, and map the Milky Way. The massive data throughput of the survey will have transformative effects on other areas of astrophysics.
ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES
(2022)
Article
Astronomy & Astrophysics
N. Rodriguez-Segovia, G. Hajdu, M. Catelan, F. Espinoza-Arancibia, G. Boggiano, C. Cenzano, E. H. Garces, K. Joachimi, C. Munoz-Lopez, C. Ordenes-Huanca, C. Orquera-Rojas, P. Torres, A. Valenzuela-Navarro
Summary: Studying PCR as a probe of changes in the interior structure and evolutionary stages of classical Cepheids in the LMC, researchers obtained accurate PCR values for 1303 stars, the largest single galaxy sample to date. The derived PCR values are largely consistent with theoretical expectations and previous computations, with the discovery of cyclic behavior in long-period sources and two first-crossing Cepheid candidates.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Dani Sprague, Connor Culhane, Marina Kounkel, Richard Olney, K. R. Covey, Brian Hutchinson, Ryan Lingg, Keivan G. Stassun, Carlos G. Roman-Zuniga, Alexandre Roman-Lopes, David Nidever, Rachael L. Beaton, Jura Borissova, Amelia Stutz, Guy S. Stringfellow, Karla Pena Ramirez, Valeria Ramirez-Preciado, Jesus Hernandez, Jinyoung Serena Kim, Richard R. Lane
Summary: This paper presents a convolutional neural network, APOGEE Net, trained on APOGEE spectra to predict T-eff, log g, and [Fe/H] parameters for stars of different masses. The catalog of stars predicted by this network allows for a detailed investigation of the star-forming history of the Milky Way and the Magellanic clouds.
ASTRONOMICAL JOURNAL
(2022)
Article
Astronomy & Astrophysics
Athanasios Papageorgiou, Panagiota-Eleftheria Christopoulou, C. E. Ferreira Lopes, Eleni Lalounta, Marcio Catelan, Andrew J. Drake
Summary: In this study, the photometric analysis of three ultra-short-period total eclipsing binaries in contact configuration was presented. The relative physical parameters and approximate absolute parameters of these systems were derived using archival light curves and new multiband photometric observations. The best photometric solution and error budget estimation for each system were obtained through optimization and sampling methods. The origin and evolutionary status of these ultra-short-period contact binaries were discussed in detail in the context of the detached binary formation channel.
ASTRONOMICAL JOURNAL
(2023)
Article
Astronomy & Astrophysics
Hunter Campbell, Elliott Khilfeh, Kevin R. Covey, Marina Kounkel, Richard Ballantyne, Sabrina Corey, Carlos G. Roman-Zuniga, Jesus Hernandez, Ezequiel Manzo Martinez, Karla Pena Ramirez, Alexandre Roman-Lopes, Keivan G. Stassun, Guy S. Stringfellow, Jura Borissova, S. Drew Chojnowski, Valeria Ramirez-Preciado, Jinyoung Serena Kim, Javier Serna, Amelia M. Stutz, Ricardo Lopez-Valdivia, Genaro Suarez, Jason E. Ybarra, Penelope Longa-Pena, Jose G. Fernandez-Trincado
Summary: Very young stars with strong magnetic fields channel ionized gas from their circumstellar disks to their surfaces, emitting hydrogen spectral lines upon impact. We measured the equivalent widths of Brackett emission lines in 1101 APOGEE spectra of 326 pre-main sequence accretors to determine the density and temperature of the gas in these accretion streams. Our measurements and model fitting show that the electron density ranges from 10^11 to 10^12 cm^-3, and the excitation temperature is inversely correlated with the electron density, ranging from 5000 K to 12,500 K.
ASTROPHYSICAL JOURNAL
(2023)
Article
Astronomy & Astrophysics
Justin A. Kader, Catherine A. Pilachowski, Christian Johnson, R. Michael Rich, Michael D. Young, Iulia T. Simion, William Clarkson, Scott Michael, Andrea Kunder, Anna Katherina Vivas, Andreas J. Koch-Hansen, Tommaso Marchetti
Summary: We present photometric evidence for multiple stellar populations in globular clusters, indicating the importance of ground-based u-band photometry in studying resolved GCs. Our study reveals the presence of at least two populations in all 14 clusters, with some clusters potentially containing three populations.
ASTROPHYSICAL JOURNAL
(2022)
Article
Astronomy & Astrophysics
Melissa L. Graham, Robert A. Knop, Thomas D. Kennedy, Peter E. Nugent, Eric Bellm, Marcio Catelan, Avi Patel, Hayden Smotherman, Monika Soraisam, Steven Stetzler, Lauren N. Aldoroty, Autumn Awbrey, Karina Baeza-Villagra, Pedro H. Bernardinelli, Federica Bianco, Dillon Brout, Riley Clarke, William Clarkson, Thomas Collett, James R. A. Davenport, Shenming Fu, John E. Gizis, Ari Heinze, Lei Hu, Saurabh W. Jha, Mario Juric, J. Bryce Kalmbach, Alex Kim, Chien-Hsiu Lee, Chris Lidman, Mark Magee, Clara E. Martinez-Vazquez, Thomas Matheson, Gautham Narayan, Antonella Palmese, Christopher A. Phillips, Markus Rabus, Armin Rest, Nicolas Rodriguez-Segovia, Rachel Street, A. Katherina Vivas, Lifan Wang, Nicholas Wolf, Jiawen Yang
Summary: This paper presents a new optical imaging survey using the Dark Energy Camera (DECam) on the 4-m Blanco telescope at the Cerro Tololo Inter-American Observatory (CTIO) to study four deep drilling fields (two Galactic and two extragalactic). The survey provides >4000 images covering 21 deg(2), with multiple epochs and filters, and focuses on characterizing and analyzing the detected sources, including faint and fast variable and transient sources. The paper also presents calibrated light curves and discusses preliminary scientific findings in various areas of research.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
P. Sanchez-Saez, J. Arredondo, A. Bayo, P. Arevalo, F. E. Bauer, G. Cabrera-Vives, M. Catelan, P. Coppi, P. A. Estevez, F. Forster, L. Hernandez-Garcia, P. Huijse, R. Kurtev, P. Lira, A. M. Munoz Arancibia, G. Pignata
Summary: This study presents a classifier based on variability, color, and morphology to identify different classes of transients and non-variable sources from ZTF DR11 data. The model was developed primarily to identify AGN for observation by the ChANGES survey, but it also has broader applications in time-domain astronomy.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
Justin A. Kader, Catherine A. Pilachowski, Christian I. Johnson, R. Michael Rich, Michael D. Young, Iulia T. Simion, William I. Clarkson, Scott Michael, Andrea Kunder, Anna Katherina Vivas, Andreas J. Koch-Hansen, Tommaso Marchetti
Summary: We present wide-field, high resolution maps of the color excess for 14 globular clusters toward the Southern Galactic bulge. These maps trace interstellar extinction by dust down to 5'' scales and show residual broadening in the color-magnitude diagrams for the target globular clusters. The broadening is likely driven by star-to-star elemental abundance variations.
ASTROPHYSICAL JOURNAL
(2023)
Article
Astronomy & Astrophysics
Shivani P. Shah, Rana Ezzeddine, Alexander P. Ji, Terese T. Hansen, Ian U. Roederer, Marcio Catelan, Zoe Hackshaw, Erika M. Holmbeck, Timothy C. Beers, Rebecca Surman
Summary: The uranium abundances of metal-poor r-process enhanced (RPE) stars can be reliably determined using multiple uranium ii lines, which allows for the accurate determination of their ages. This provides valuable insights into the chemical enrichment and evolution of the early universe.
ASTROPHYSICAL JOURNAL
(2023)
Article
Astronomy & Astrophysics
Caleb I. Canas, Chad F. Bender, Suvrath Mahadevan, Dmitry Bizyaev, Nathan De Lee, Scott W. Fleming, Fred Hearty, Steven R. Majewski, Christian Nitschelm, Donald P. Schneider, Javier Serna, Keivan G. Stassun, Gudmundur Stefansson, Guy S. Stringfellow, John C. Wilson
Summary: We have characterized 28 low-mass companions to Kepler objects of interest (KOIs), which were detected as transiting companions to Sunlike stars by the Kepler mission. Using the APOGEE-N, we confirm these companions as single-lined spectroscopic binaries and derive fundamental parameters for them. The APOGEE-N data provide reliable radial velocities and enable detailed characterization of individual systems and the inference of orbital elements for faint KOIs.
ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES
(2023)
Article
Astronomy & Astrophysics
F. Perez-Galarce, K. Pichara, P. Huijse, M. Catelan, D. Mery
Summary: Machine learning models and algorithms have been used to process and extract knowledge from time-series surveys, but few studies have addressed the data shift problem in labeled training sets, which can undermine prediction performance on unseen data. In this paper, a scalable and adaptable approach is proposed to mitigate the data shift problem during the training of a multi-layer perceptron for RR Lyrae classification. The approach incorporates informative regularization and uses a two-step back-propagation algorithm to integrate prior knowledge into the neural network's training process.
ASTRONOMY AND COMPUTING
(2023)
Article
Astronomy & Astrophysics
Athanasios Papageorgiou, Panagiota-Eleftheria Christopoulou, Eleni Lalounta, C. E. Ferreira Lopes, Marcio Catelan, Andrew J. Drake, Panayiotis Hantzios, Ioannis Alikakos
Summary: We conducted a multiband photometric analysis of the low-mass-ratio contact binary system CRTS J163819.6+03485, which has a period of 0.2053321 day below the contact binary period limit. The unique combination of mass ratio and period makes this system a valuable object for studying eclipsing binaries. By using new multiband photometric observations and the pikaia genetic algorithm optimizer, we explored the parameter space of this system through a detailed scan in the mass ratio-inclination plane. We obtained the best set of relative physical parameters and uncertainties using the Markov Chain Monte Carlo sampling method.
ASTROPHYSICAL JOURNAL
(2023)
Correction
Astronomy & Astrophysics
Caleb I. Canas, Chad F. Bender, Suvrath Mahadevan, Dmitry Bizyaev, Nathan De Lee, Scott W. Fleming, Fred Hearty, Steven R. Majewski, Christian Nitschelm, Donald P. Schneider, Javier Serna, Keivan G. Stassun, Gudmundur Stefansson, Guy S. Stringfellow, John C. Wilson
ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES
(2023)
Proceedings Paper
Engineering, Mechanical
John C. Wilson, Dan Rocheleau, John Fox, Louis Green, Donald Harkins, Dirk E. Schoellner, Stuart Melton, Lori Seagle, Zane Fitzgerald, David Nidever, Nathan De Lee, Jon Holtzman, Emily Farr, Sarah E. Tuttle, Audrey Oravetz, Katie Grabowski, Kaike Pan, Dmitry Bizyaev, Jamey Eriksen, Stefanie Wachter, Solange Ramirez, Juna A. Kollmeier
Summary: This passage discusses the field retermination of high-fiber count MTP fiber connectors used with the APOGEE spectrograph at Apache Point Observatory (APO) in 2021, addressing lessons-learned, wear-analysis of removed MTPs, and throughput of the fiber train with the newly terminated fibers in SDSS-V. For the past decade, the spectrograph at APO has relied upon rapid changes of ten MTP connectors, each containing 30 terminated fibers, and all contained within a custom gang connector system.
ADVANCES IN OPTICAL AND MECHANICAL TECHNOLOGIES FOR TELESCOPES AND INSTRUMENTATION V
(2022)
