R. Tomas Garcia

R. Tomas Garcia
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R. Tomas Garcia

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Pub Categories

Solar and Stellar Astrophysics (38)
Astrophysics of Galaxies (7)
Earth and Planetary Astrophysics (7)
Instrumentation and Methods for Astrophysics (3)
Mathematics - Commutative Algebra (2)
Quantitative Biology - Neurons and Cognition (2)
Nuclear Theory (1)
Physics - Plasma Physics (1)
Computer Science - Programming Languages (1)
High Energy Astrophysical Phenomena (1)
General Relativity and Quantum Cosmology (1)
Mathematics - Dynamical Systems (1)
Physics - Atmospheric and Oceanic Physics (1)
Mathematics - Algebraic Geometry (1)
Quantitative Biology - Subcellular Processes (1)
Physics - Geophysics (1)
Physics - Accelerator Physics (1)
High Energy Physics - Experiment (1)
Mathematics - Metric Geometry (1)

Publications Authored By R. Tomas Garcia

We present a comparison of parallaxes and radii from asteroseismology and Gaia DR1 (TGAS) for 2200 Kepler stars spanning from the main sequence to the red giant branch. We show that previously identified offsets between TGAS parallaxes and distances derived from asteroseismology and eclipsing binaries have likely been overestimated for parallaxes <~ 5-10 mas (~ 90-98% of the TGAS sample). The observed differences in our sample can furthermore be partially compensated by adopting a hotter Teff scale (such as the infrared flux method) instead of spectroscopic temperatures for dwarfs and subgiants. Read More

We present an analysis of 168 oscillating red giants from NASA's $Kepler$ mission that exhibit anomalous peaks in their Fourier amplitude spectra. These peaks result from ellipsoidal variations which are indicative of binary star systems, at frequencies such that the orbit of any stellar companion would be within the convective envelope of the red giant. Alternatively, the observed phenomenon may be due to a close binary orbiting a red giant in a triple system, or chance alignments of foreground or background binary systems contaminating the target pixel aperture. Read More

In the updated APOGEE-Kepler catalog, we have asteroseismic and spectroscopic data for over 3000 first ascent red giants. Given the size and accuracy of this sample, these data offer an unprecedented test of the accuracy of stellar models on the post-main-sequence. When we compare these data to theoretical predictions, we find a metallicity dependent temperature offset with a slope of around 100 K per dex in metallicity. Read More

During asymmetric cell divisions, cortical dyneins generate forces essential to position the spindle after polarity cues, prescribing daughter cells fate. In nematode zygote, cortical dynein pulls on microtubules transiently, raising the question of its targeting and dynamics. Tracking and fluorescence correlation spectroscopy revealed that in the cytoplasm, dynein spots displayed directed motions toward the cortex, localized at microtubule plus-ends through EBP-2/EB but are not actively transported. Read More

Stellar clusters form by gravitational collapse of turbulent molecular clouds, with up to several thousand stars per cluster. They are thought to be the birthplace of most stars and therefore play an important role in our understanding of star formation, a fundamental problem in astrophysics. The initial conditions of the molecular cloud establish its dynamical history until the stellar cluster is born. Read More

Since CoRoT observations unveiled the very low amplitude modes that form a flat plateau in the power spectrum structure of delta Scuti stars, the nature of this phenomenon, including the possibility of spurious signals due to the light curve analysis, has been a matter of long-standing scientific debate. We contribute to this debate by finding the structural parameters of a sample of four delta Scuti stars, CID 546, CID 3619, CID 8669, and KIC 5892969, and looking for a possible relation between these stars' structural parameters and their power spectrum structure. For the purposes of characterization, we developed a method of studying and analysing the power spectrum with high precision and have applied it to both CoRoT and Kepler light curves. Read More

We present stellar properties (mass, age, radius, distances) of 57 stars from a seismic inference using full-length data sets from Kepler. These stars comprise active stars, planet-hosts, solar-analogs, and binary systems. We validate the distances derived from the astrometric Gaia-Tycho solution. Read More

The Kepler space telescope has provided time series of red giants of such unprecedented quality that a detailed asteroseismic analysis becomes possible. For a limited set of about a dozen red giants, the observed oscillation frequencies obtained by peak-bagging together with the most recent pulsation codes allowed us to reliably determine the core/envelope rotation ratio. The results so far show that the current models are unable to reproduce the rotation ratios, predicting higher values than what is observed and thus indicating that an efficient angular momentum transport mechanism should be at work. Read More

We report here on our search for excess power in photometry of Neptune collected by the K2 mission that may be due to intrinsic global oscillations of the planet Neptune. To conduct this search, we developed new methods to correct for instrumental effects such as intrapixel variability and gain variations. We then extracted and analyzed the time-series photometry of Neptune from 49 days of nearly continuous broadband photometry of the planet. Read More

Lithium abundance A(Li) and surface rotation are good diagnostic tools to probe the internal mixing and angular momentum transfer in stars. We explore the relation between surface rotation, A(Li) and age in a sample of seismic solar-analogue (SA) stars and study their possible binary nature. We select a sample of 18 SA observed by the NASA Kepler satellite for an in-depth analysis. Read More

The Kepler space telescope yielded unprecedented data for the study of solar-like oscillations in other stars. The large samples of multi-year observations posed an enormous data analysis challenge that has only recently been surmounted. Asteroseismic modeling has become more sophisticated over time, with better methods gradually developing alongside the extended observations and improved data analysis techniques. Read More

The brain processes information about the environment via neural codes. The neural ideal was introduced recently as an algebraic object that can be used to better understand the combinatorial structure of neural codes. Every neural ideal has a particular generating set, called the canonical form, that directly encodes a minimal description of the receptive field structure intrinsic to the neural code. Read More

Context: Constraints on the internal rotation of red giants are now available thanks to asteroseismic observations. Preliminary comparisons with rotating stellar models indicate that an undetermined additional process for the internal transport of angular momentum is required in addition to purely hydrodynamic processes. Aims: We investigate how asteroseismic measurements of red giants can help us characterize the additional transport mechanism. Read More

The SEIS (Seismic Experiment for Interior Structures) instrument onboard the InSight mission to Mars is the critical instrument for determining the interior structure of Mars, the current level of tectonic activity and the meteorite flux. Meeting the performance requirements of the SEIS instrument is vital to successfully achieve these mission objectives. Here we analyse in-situ wind measurements from previous Mars space missions to understand the wind environment that we are likely to encounter on Mars, and then we use an elastic ground deformation model to evaluate the mechanical noise contributions on the SEIS instrument due to the interaction between the Martian winds and the InSight lander. Read More

NASA's K2 mission is observing tens of thousands of stars along the ecliptic, providing data suitable for large scale asteroseismic analyses to inform galactic archaeology studies. Its first campaign covered a field near the north galactic cap, a region never covered before by large asteroseismic-ensemble investigations, and was therefore of particular interest for exploring this part of our Galaxy. Here we report the asteroseismic analysis of all stars selected by the K2 Galactic Archaeology Program during the mission's "North Galactic Cap" campaign 1. Read More

Quasi-periodic modulations of the stellar light curve may result from dark spots crossing the visible stellar disc. Due to differential rotation, spots at different latitudes generally have different rotation periods. Hence, by studying spot-induced modulations, one can learn about stellar surface (differential) rotation and magnetic activity. Read More

Starspots are cooler and darker than the stellar surface. Therefore, the emitted flux of a star changes when spots are visible on its surface. The presence of spots together with the stellar rotation leads to a periodic modulation on the light curve. Read More

Calibration issues associated to scrambled collateral smear affecting the Kepler short-cadence data were discovered in the Data Release 24 and were found to be present in all the previous data releases since launch. In consequence, a new Data Release 25 was reprocessed to correct for these problems. We perform here a preliminary study to evaluate the impact on the extracted global seismic and background parameters between data releases. Read More

Stars similar to the Sun, known as solar analogues, provide an excellent opportunity to study the preceding and following evolutionary phases of our host star. The unprecedented quality of photometric data collected by the \Kepler NASA mission allows us to characterise solar-like stars through asteroseismology and study diagnostics of stellar evolution, such as variation of magnetic activity, rotation and the surface lithium abundance. In this project, presented in a series of papers by Salabert et al. Read More

The Kepler mission has been a success in both exoplanet search and stellar physics studies. Red giants have actually been quite a highlight in the Kepler scene. The Kepler long and almost continuous four-year observations allowed us to detect oscillations in more than 15,000 red giants targeted by the mission. Read More

Sun-as-a star observations put our star as a reference for stellar observations. Here, I review the activities in which the SPACEINN global seismology team (Working Package WP4.1) has worked during the past 3 years. Read More

The unparalleled photometric data obtained by NASA's Kepler Space Telescope has led to an improved understanding of stellar structure and evolution - in particular for solar-like oscillators in this context. Binary stars are fascinating objects. Because they were formed together, binary systems provide a set of two stars with very well constrained parameters. Read More

Finding solar-analog stars with fundamental properties as close as possible to the Sun and studying the characteristics of their surface magnetic activity is a very promising way to understand the solar variability and its associated dynamo process. However, the identification of solar-analog stars depends on the accuracy of the estimated stellar parameters. Thanks to the photometric CoROT and Kepler space missions, the addition of asteroseismic data was proven to provide the most accurate fundamental properties that can be derived from stellar modeling today. Read More

A major area in neuroscience research is the study of how the brain processes spatial information. Neurons in the brain represent external stimuli via neural codes. These codes often arise from stereotyped stimulus-response maps, associating to each neuron a convex receptive field. Read More

Binary star systems are important for understanding stellar structure and evolution, and are especially useful when oscillations can be detected and analysed with asteroseismology. However, only four systems are known in which solar-like oscillations are detected in both components. Here, we analyse the fifth such system, HD 176465, which was observed by Kepler. Read More

Authors: The CLIC, CLICdp collaborations, :, M. J. Boland, U. Felzmann, P. J. Giansiracusa, T. G. Lucas, R. P. Rassool, C. Balazs, T. K. Charles, K. Afanaciev, I. Emeliantchik, A. Ignatenko, V. Makarenko, N. Shumeiko, A. Patapenka, I. Zhuk, A. C. Abusleme Hoffman, M. A. Diaz Gutierrez, M. Vogel Gonzalez, Y. Chi, X. He, G. Pei, S. Pei, G. Shu, X. Wang, J. Zhang, F. Zhao, Z. Zhou, H. Chen, Y. Gao, W. Huang, Y. P. Kuang, B. Li, Y. Li, J. Shao, J. Shi, C. Tang, X. Wu, L. Ma, Y. Han, W. Fang, Q. Gu, D. Huang, X. Huang, J. Tan, Z. Wang, Z. Zhao, T. Laštovička, U. Uggerhoj, T. N. Wistisen, A. Aabloo, K. Eimre, K. Kuppart, S. Vigonski, V. Zadin, M. Aicheler, E. Baibuz, E. Brücken, F. Djurabekova, P. Eerola, F. Garcia, E. Haeggström, K. Huitu, V. Jansson, V. Karimaki, I. Kassamakov, A. Kyritsakis, S. Lehti, A. Meriläinen, R. Montonen, T. Niinikoski, K. Nordlund, K. Österberg, M. Parekh, N. A. Törnqvist, J. Väinölä, M. Veske, W. Farabolini, A. Mollard, O. Napoly, F. Peauger, J. Plouin, P. Bambade, I. Chaikovska, R. Chehab, M. Davier, W. Kaabi, E. Kou, F. LeDiberder, R. Pöschl, D. Zerwas, B. Aimard, G. Balik, J. -P. Baud, J. -J. Blaising, L. Brunetti, M. Chefdeville, C. Drancourt, N. Geoffroy, J. Jacquemier, A. Jeremie, Y. Karyotakis, J. M. Nappa, S. Vilalte, G. Vouters, A. Bernard, I. Peric, M. Gabriel, F. Simon, M. Szalay, N. van der Kolk, T. Alexopoulos, E. N. Gazis, N. Gazis, E. Ikarios, V. Kostopoulos, S. Kourkoulis, P. D. Gupta, P. Shrivastava, H. Arfaei, M. K. Dayyani, H. Ghasem, S. S. Hajari, H. Shaker, Y. Ashkenazy, H. Abramowicz, Y. Benhammou, O. Borysov, S. Kananov, A. Levy, I. Levy, O. Rosenblat, G. D'Auria, S. Di Mitri, T. Abe, A. Aryshev, T. Higo, Y. Makida, S. Matsumoto, T. Shidara, T. Takatomi, Y. Takubo, T. Tauchi, N. Toge, K. Ueno, J. Urakawa, A. Yamamoto, M. Yamanaka, R. Raboanary, R. Hart, H. van der Graaf, G. Eigen, J. Zalieckas, E. Adli, R. Lillestøl, L. Malina, J. Pfingstner, K. N. Sjobak, W. Ahmed, M. I. Asghar, H. Hoorani, S. Bugiel, R. Dasgupta, M. Firlej, T. A. Fiutowski, M. Idzik, M. Kopec, M. Kuczynska, J. Moron, K. P. Swientek, W. Daniluk, B. Krupa, M. Kucharczyk, T. Lesiak, A. Moszczynski, B. Pawlik, P. Sopicki, T. Wojtoń, L. Zawiejski, J. Kalinowski, M. Krawczyk, A. F. Żarnecki, E. Firu, V. Ghenescu, A. T. Neagu, T. Preda, I-S. Zgura, A. Aloev, N. Azaryan, J. Budagov, M. Chizhov, M. Filippova, V. Glagolev, A. Gongadze, S. Grigoryan, D. Gudkov, V. Karjavine, M. Lyablin, A. Olyunin, A. Samochkine, A. Sapronov, G. Shirkov, V. Soldatov, A. Solodko, E. Solodko, G. Trubnikov, I. Tyapkin, V. Uzhinsky, A. Vorozhtov, E. Levichev, N. Mezentsev, P. Piminov, D. Shatilov, P. Vobly, K. Zolotarev, I. Bozovic Jelisavcic, G. Kacarevic, S. Lukic, G. Milutinovic-Dumbelovic, M. Pandurovic, U. Iriso, F. Perez, M. Pont, J. Trenado, M. Aguilar-Benitez, J. Calero, L. Garcia-Tabares, D. Gavela, J. L. Gutierrez, D. Lopez, F. Toral, D. Moya, A. Ruiz Jimeno, I. Vila, T. Argyropoulos, C. Blanch Gutierrez, M. Boronat, D. Esperante, A. Faus-Golfe, J. Fuster, N. Fuster Martinez, N. Galindo Muñoz, I. García, J. Giner Navarro, E. Ros, M. Vos, R. Brenner, T. Ekelöf, M. Jacewicz, J. Ögren, M. Olvegård, R. Ruber, V. Ziemann, D. Aguglia, N. Alipour Tehrani, A. Andersson, F. Andrianala, F. Antoniou, K. Artoos, S. Atieh, R. Ballabriga Sune, M. J. Barnes, J. Barranco Garcia, H. Bartosik, C. Belver-Aguilar, A. Benot Morell, D. R. Bett, S. Bettoni, G. Blanchot, O. Blanco Garcia, X. A. Bonnin, O. Brunner, H. Burkhardt, S. Calatroni, M. Campbell, N. Catalan Lasheras, M. Cerqueira Bastos, A. Cherif, E. Chevallay, B. Constance, R. Corsini, B. Cure, S. Curt, B. Dalena, D. Dannheim, G. De Michele, L. De Oliveira, N. Deelen, J. P. Delahaye, T. Dobers, S. Doebert, M. Draper, F. Duarte Ramos, A. Dubrovskiy, K. Elsener, J. Esberg, M. Esposito, V. Fedosseev, P. Ferracin, A. Fiergolski, K. Foraz, A. Fowler, F. Friebel, J-F. Fuchs, C. A. Fuentes Rojas, A. Gaddi, L. Garcia Fajardo, H. Garcia Morales, C. Garion, L. Gatignon, J-C. Gayde, H. Gerwig, A. N. Goldblatt, C. Grefe, A. Grudiev, F. G. Guillot-Vignot, M. L. Gutt-Mostowy, M. Hauschild, C. Hessler, J. K. Holma, E. Holzer, M. Hourican, D. Hynds, Y. Inntjore Levinsen, B. Jeanneret, E. Jensen, M. Jonker, M. Kastriotou, J. M. K. Kemppinen, R. B. Kieffer, W. Klempt, O. Kononenko, A. Korsback, E. Koukovini Platia, J. W. Kovermann, C-I. Kozsar, I. Kremastiotis, S. Kulis, A. Latina, F. Leaux, P. Lebrun, T. Lefevre, L. Linssen, X. Llopart Cudie, A. A. Maier, H. Mainaud Durand, E. Manosperti, C. Marelli, E. Marin Lacoma, R. Martin, S. Mazzoni, G. Mcmonagle, O. Mete, L. M. Mether, M. Modena, R. M. Münker, T. Muranaka, E. Nebot Del Busto, N. Nikiforou, D. Nisbet, J-M. Nonglaton, F. X. Nuiry, A. Nürnberg, M. Olvegard, J. Osborne, S. Papadopoulou, Y. Papaphilippou, A. Passarelli, M. Patecki, L. Pazdera, D. Pellegrini, K. Pepitone, E. Perez Codina, A. Perez Fontenla, T. H. B. Persson, M. Petrič, F. Pitters, S. Pittet, F. Plassard, R. Rajamak, S. Redford, Y. Renier, S. F. Rey, G. Riddone, L. Rinolfi, E. Rodriguez Castro, P. Roloff, C. Rossi, V. Rude, G. Rumolo, A. Sailer, E. Santin, D. Schlatter, H. Schmickler, D. Schulte, N. Shipman, E. Sicking, R. Simoniello, P. K. Skowronski, P. Sobrino Mompean, L. Soby, M. P. Sosin, S. Sroka, S. Stapnes, G. Sterbini, R. Ström, I. Syratchev, F. Tecker, P. A. Thonet, L. Timeo, H. Timko, R. Tomas Garcia, P. Valerio, A. L. Vamvakas, A. Vivoli, M. A. Weber, R. Wegner, M. Wendt, B. Woolley, W. Wuensch, J. Uythoven, H. Zha, P. Zisopoulos, M. Benoit, M. Vicente Barreto Pinto, M. Bopp, H. H. Braun, M. Csatari Divall, M. Dehler, T. Garvey, J. Y. Raguin, L. Rivkin, R. Zennaro, A. Aksoy, Z. Nergiz, E. Pilicer, I. Tapan, O. Yavas, V. Baturin, R. Kholodov, S. Lebedynskyi, V. Miroshnichenko, S. Mordyk, I. Profatilova, V. Storizhko, N. Watson, A. Winter, J. Goldstein, S. Green, J. S. Marshall, M. A. Thomson, B. Xu, W. A. Gillespie, R. Pan, M. A Tyrk, D. Protopopescu, A. Robson, R. Apsimon, I. Bailey, G. Burt, D. Constable, A. Dexter, S. Karimian, C. Lingwood, M. D. Buckland, G. Casse, J. Vossebeld, A. Bosco, P. Karataev, K. Kruchinin, K. Lekomtsev, L. Nevay, J. Snuverink, E. Yamakawa, V. Boisvert, S. Boogert, G. Boorman, S. Gibson, A. Lyapin, W. Shields, P. Teixeira-Dias, S. West, R. Jones, N. Joshi, R. Bodenstein, P. N. Burrows, G. B. Christian, D. Gamba, C. Perry, J. Roberts, J. A. Clarke, N. A. Collomb, S. P. Jamison, B. J. A. Shepherd, D. Walsh, M. Demarteau, J. Repond, H. Weerts, L. Xia, J. D. Wells, C. Adolphsen, T. Barklow, M. Breidenbach, N. Graf, J. Hewett, T. Markiewicz, D. McCormick, K. Moffeit, Y. Nosochkov, M. Oriunno, N. Phinney, T. Rizzo, S. Tantawi, F. Wang, J. Wang, G. White, M. Woodley

The Compact Linear Collider (CLIC) is a multi-TeV high-luminosity linear e+e- collider under development. For an optimal exploitation of its physics potential, CLIC is foreseen to be built and operated in a staged approach with three centre-of-mass energy stages ranging from a few hundred GeV up to 3 TeV. The first stage will focus on precision Standard Model physics, in particular Higgs and top-quark measurements. Read More

The Hyades open cluster was targeted during Campaign 4 (C4) of the NASA K2 mission, and short-cadence data were collected on a number of cool main-sequence stars. Here, we report results on two F-type stars that show detectable oscillations of a quality that allows asteroseismic analyses to be performed. These are the first ever detections of solar-like oscillations in main-sequence stars in an open cluster. Read More

Authors: SDSS Collaboration, Franco D. Albareti, Carlos Allende Prieto, Andres Almeida, Friedrich Anders, Scott Anderson, Brett H. Andrews, Alfonso Aragon-Salamanca, Maria Argudo-Fernandez, Eric Armengaud, Eric Aubourg, Vladimir Avila-Reese, Carles Badenes, Stephen Bailey, Beatriz Barbuy, Kat Barger, Jorge Barrera-Ballesteros, Curtis Bartosz, Sarbani Basu, Dominic Bates, Giuseppina Battaglia, Falk Baumgarten, Julien Baur, Julian Bautista, Timothy C. Beers, Francesco Belfiore, Matthew Bershady, Sara Bertran de Lis, Jonathan C. Bird, Dmitry Bizyaev, Guillermo A. Blanc, Michael Blanton, Michael Blomqvist, Adam S. Bolton, J. Borissova, Jo Bovy, William Nielsen Brandt, Jonathan Brinkmann, Joel R. Brownstein, Kevin Bundy, Etienne Burtin, Nicolas G. Busca, Hugo Orlando Camacho Chavez, M. Cano Diaz, Michele Cappellari, Ricardo Carrera, Yanping Chen, Brian Cherinka, Edmond Cheung, Cristina Chiappini, Drew Chojnowski, Chia-Hsun Chuang, Haeun Chung, Rafael Fernando Cirolini, Nicolas Clerc, Roger E. Cohen, Julia M. Comerford, Johan Comparat, Marie-Claude Cousinou, Kevin Covey, Jeffrey D. Crane, Rupert Croft, Katia Cunha, Luiz da Costa, Gabriele da Silva Ilha, Jeremy Darling, James W. Davidson Jr., Kyle Dawson, Nathan De Lee, Axel de la Macorra, Sylvain de la Torre, Alice Deconto Machado, Timothee Delubac, Aleksandar M. Diamond-Stanic, John Donor, Juan Jose Downes, Niv Drory, Helion du Mas des Bourboux, Cheng Du, Tom Dwelly, Garrett Ebelke, Arthur Eigenbrot, Daniel J. Eisenstein, Yvonne P. Elsworth, Eric Emsellem, Michael Eracleous, Stephanie Escoffier, Michael L. Evans, Jesus Falcon-Barroso, Xiaohui Fan, Ginevra Favole, Emma Fernandez-Alvar, J. G. Fernandez-Trincado, Diane Feuillet, Scott W. Fleming, Andreu Font-Ribera, Gordon Freischlad, Peter Frinchaboy, Hai Fu, Yang Gao, D. A. Garcia-Hernandez, Ana E. Garcia Perez, Rafael A. Garcia, R. Garcia-Dias, Patrick Gaulme, Junqiang Ge, Douglas Geisler, Hector Gil Marin, Bruce Gillespie, Leo Girardi, Daniel Goddard, Yilen Gomez Maqueo Chew, Violeta Gonzalez-Perez, Kathleen Grabowski, Paul Green, Catherine J. Grier, Thomas Grier, Hong Guo, Julien Guy, Alex Hagen, Matt Hall, Paul Harding, R. E. Harley, Sten Hasselquist, Suzanne Hawley, Christian R. Hayes, Fred Hearty, Saskia Hekker, Hector Hernandez Toledo, Shirley Ho, David W. Hogg, Kelly Holley-Bockelmann, Jon A. Holtzman, Parker H. Holzer, Jian Hu, Daniel Huber, Timothy Alan Hutchinson, Ho Seong Hwang, Hector J. Ibarra-Medel, Inese I. Ivans, KeShawn Ivory, Kurt Jaehnig, Trey W. Jensen, Jennifer A. Johnson, Amy Jones, Eric Jullo, T. Kallinger, Karen Kinemuchi, David Kirkby, Mark Klaene, Jean-Paul Kneib, Juna A. Kollmeier, Ivan Lacerna, Richard R. Lane, Dustin Lang, Pierre Laurent, David R. Law, Jean-Marc Le Goff, Alexie Leauthaud, Cheng Li, Ran Li, Chen Li, Niu Li, Fu-Heng Liang, Yu Liang, Marcos Lima, Lihwai Lin, Lin Lin, Yen-Ting Lin, Dan Long, Sara Lucatello, Nicholas MacDonald, Chelsea L. MacLeod, J. Ted Mackereth, Suvrath Mahadevan, Marcio Antonio-Geimba Maia, Roberto Maiolino, Steven R. Majewski, Olena Malanushenko, Nicolas Dullius Mallmann, Arturo Manchado, Claudia Maraston, Rui Marques-Chaves, Inma Martinez Valpuesta, Karen L. Masters, Savita Mathur, Ian D. McGreer, Andrea Merloni, Michael R. Merrifield, Szabolcs Meszaros, Andres Meza, Andrea Miglio, Ivan Minchev, Karan Molaverdikhani, Antonio D. Montero-Dorta, Benoit Mosser, Demitri Muna, Adam Myers, Preethi Nair, Kirpal Nandra, Melissa Ness, Jeffrey A. Newman, Robert C. Nichol, David L. Nidever, Christian Nitschelm, Julia O'Connell, Audrey Oravetz, Nelson Padilla, Nathalie Palanque-Delabrouille, Kaike Pan, John Parejko, Isabelle Paris, John A. Peacock, Sebastien Peirani, Marcos Pellejero-Ibanez, Samantha Penny, Will J. Percival, Jeffrey W. Percival, Ismael Perez-Fournon, Patrick Petitjean, Matthew Pieri, Marc H. Pinsonneault, Alice Pisani, Francisco Prada, Abhishek Prakash, Natalie Price-Jones, M. Jordan Raddick, Mubdi Rahman, Anand Raichoor, Sandro Barboza Rembold, A. M. Reyna, James Rich, Hannah Richstein, Jethro Ridl, Rogerio Riffel, Rogemar A. Riffel, Hans-Walter Rix, Annie C. Robin, Constance M. Rockosi, Sergio Rodriguez-Torres, Thaise S. Rodrigues, Natalie Roe, A. Roman Lopes, Carlos Roman-Zuniga, Ashley J. Ross, Graziano Rossi, John Ruan, Rossana Ruggeri, Jessie C. Runnoe, Salvador Salazar-Albornoz, Mara Salvato, Ariel G. Sanchez, Sebastian F. Sanchez, Jose R. Sanchez-Gallego, Basilio Xavier Santiago, Ricardo Schiavon, Jaderson S. Schimoia, Eddie Schlafly, David J. Schlegel, Donald P. Schneider, Ralph Schoenrich, Mathias Schultheis, Axel Schwope, Hee-Jong Seo, Aldo Serenelli, Branimir Sesar, Zhengyi Shao, Matthew Shetrone, Michael Shull, Victor Silva Aguirre, M. F. Skrutskie, Anže Slosar, Michael Smith, Verne V. Smith, Jennifer Sobeck, Garrett Somers, Diogo Souto, David V. Stark, Keivan G. Stassun, Matthias Steinmetz, Dennis Stello, Thaisa Storchi Bergmann, Michael A. Strauss, Alina Streblyanska, Guy S. Stringfellow, Genaro Suarez, Jing Sun, Manuchehr Taghizadeh-Popp, Baitian Tang, Charling Tao, Jamie Tayar, Mita Tembe, Daniel Thomas, Jeremy Tinker, Rita Tojeiro, Christy Tremonti, Nicholas Troup, Jonathan R. Trump, Eduardo Unda-Sanzana, O. Valenzuela, Remco van den Bosch, Mariana Vargas-Magana, Jose Alberto Vazquez, Sandro Villanova, M. Vivek, Nicole Vogt, David Wake, Rene Walterbos, Yuting Wang, Enci Wang, Benjamin Alan Weaver, Anne-Marie Weijmans, David H. Weinberg, Kyle B. Westfall, David G. Whelan, Eric Wilcots, Vivienne Wild, Rob A. Williams, John Wilson, W. M. Wood-Vasey, Dominika Wylezalek, Ting Xiao, Renbin Yan, Meng Yang, Jason E. Ybarra, Christophe Yeche, Fang-Ting Yuan, Nadia Zakamska, Olga Zamora, Gail Zasowski, Kai Zhang, Cheng Zhao, Gong-Bo Zhao, Zheng Zheng, Zheng Zheng, Zhi-Min Zhou, Guangtun Zhu, Joel C. Zinn, Hu Zou

The fourth generation of the Sloan Digital Sky Survey (SDSS-IV) began observations in July 2014. It pursues three core programs: APOGEE-2, MaNGA, and eBOSS. In addition, eBOSS contains two major subprograms: TDSS and SPIDERS. Read More

We identify a set of 18 solar analogs among the seismic sample of solar-like stars observed by the Kepler satellite rotating between 10 and 40 days. This set is constructed using the asteroseismic stellar properties derived using either the global oscillation properties or the individual acoustic frequencies. We measure the magnetic activity properties of these stars using observations collected by the photometric Kepler satellite and by the ground-based, high-resolution Hermes spectrograph mounted on the Mercator telescope. Read More

The locus of centers of inscribed circles in triangles, the 3-periodic orbits of an elliptic billiard, is also an ellipse. In this work we obtain the canonical equation of this ellipse, complementing the previous results obtained by O. Romaskevich. Read More

Asteroseismology has proven to be an excellent tool to determine not only the global stellar properties with a good precision but also to infer stellar structure, dynamics, and evolution for a large sample of Kepler stars. Prior to the launch of the mission the properties of Kepler targets were inferred from broadband photometry, leading to the Input Catalog (KIC Brown et al. 2011). Read More

Frequencies of acoustic and mixed modes in red giant stars are now determined with high precision thanks to the long continuous observations provided by the NASA Kepler mission. Here we consider the eigenfrequencies of nineteen low-luminosity red giant stars selected by Corsaro et al. (2015) for a detailed peak-bagging analysis. Read More

With the advent of the space missions CoRoT and Kepler, it has become feasible to determine precise asteroseismic masses and ages for large samples of red-giant stars. In this paper, we present the CoRoGEE dataset -- obtained from CoRoT lightcurves for 606 red giant stars in two fields of the Galactic disc which have been co-observed for an ancillary project of APOGEE. We have used the Bayesian parameter estimation code PARAM to calculate distances, extinctions, masses, and ages for these stars in a homogeneous analysis, resulting in relative statistical uncertainties of $\sim2\%$ in distance, $\sim4\%$ in radius, $\sim9\%$ in mass and $\sim25\%$ in age. Read More

Aims. We aim studying the use of cross-correlation techniques to infer the frequency shifts induced by changing magnetic fields in the p-mode frequencies and provide precise estimation of the error bars. Methods. Read More

The continuous photometric observations collected by the Kepler satellite over 4 years provide a whelm of data with an unequalled quantity and quality for the study of stellar evolution of more than 200000 stars. Moreover, the length of the dataset provide a unique source of information to detect magnetic activity and associated temporal variability in the acoustic oscillations. In this regards, the Kepler mission was awaited with great expectation. Read More

The asteroseismology of red giant stars has continued to yield surprises since the onset of high-precision photometry from space-based observations. An exciting new theoretical result shows that the previously observed suppression of dipole oscillation modes in red giants can be used to detect strong magnetic fields in the stellar cores. A fundamental facet of the theory is that nearly all the mode energy leaking into the core is trapped by the magnetic greenhouse effect. Read More

Dipole mixed pulsation modes of consecutive radial order have been detected for thousands of low-mass red-giant stars with the NASA space telescope Kepler. Such modes have the potential to reveal information on the physics of the deep stellar interior. Different methods have been proposed to derive an observed value for the gravity-mode period spacing, the most prominent one relying on a relation derived from asymptotic pulsation theory applied to the gravity-mode character of the mixed modes. Read More

We study radial particle transport in stellarator plasmas using cryogenic pellet injection. By means of perturbative experiments, we estimate the experimental particle flux and compare it with neoclassical simulations. Experimental evidence is obtained of the fact that core depletion in helical devices can be slowed-down even by pellets that do not reach the core region. Read More

We report the discovery of a partial conservation law obeyed by a schematic Hamiltonian of two protons and two neutrons in a j shell. In our Hamiltonian the interaction matrix element of two nucleons with combined angular momentum J is linear in J for even J and constant for odd J. It turns out that in some stationary states the sum J_p + J_n of the angular momenta J_p and J_n of the proton and neutron pairs is conserved. Read More

A knowledge of stellar ages is crucial for our understanding of many astrophysical phenomena, and yet ages can be difficult to determine. As they become older, stars lose mass and angular momentum, resulting in an observed slowdown in surface rotation. The technique of 'gyrochronology' uses the rotation period of a star to calculate its age. Read More

Magnetic fields play a role in almost all stages of stellar evolution. Most low-mass stars, including the Sun, show surface fields that are generated by dynamo processes in their convective envelopes. Intermediate-mass stars do not have deep convective envelopes, although 10% exhibit strong surface fields that are presumed to be residuals from the stellar formation process. Read More

We present a set of simulations of relativistic jets from accretion disk initial setup with a new code in Fortran 90 to get numerical solutions of a system of General Relativistic Magnetohydrodynamics (GRMHD) partial differential equations in a fixed Black Hole (BH) spacetime which is able to show substructures formations inside the jet as well as a lobe formation on the disk. For this, a central scheme of finite volume method without dimensional split and no Riemann solvers (a Nessyahu-Tadmor method) was implemented. Thus, we were able to obtain stable numerical solutions with spurious oscillations under control and no excessive numerical dissipation. Read More

Solar-analog stars provide an excellent opportunity to study the Sun's evolution, i.e. the changes with time in stellar structure, activity, or rotation for solar-like stars. Read More

In this paper we study the dynamics of the stellar interior of the early red-giant star KIC 4448777 by asteroseismic inversion of 14 splittings of the dipole mixed modes obtained from {\it Kepler} observations. In order to overcome the complexity of the oscillation pattern typical of red-giant stars, we present a procedure which involves a combination of different methods to extract the rotational splittings from the power spectrum. We find not only that the core rotates faster than the surface, confirming previous inversion results generated for other red giants (Deheuvels et al. Read More

Abstracting Gradual Typing (AGT) is an approach to systematically deriving gradual counterparts to static type disciplines. The approach consists of defining the semantics of gradual types by interpreting them as sets of static types, and then defining an optimal abstraction back to gradual types. These operations are used to lift the static discipline to the gradual setting. Read More

One of the most difficult properties to derive for stars is their age. For cool main-sequence stars, gyrochronology relations can be used to infer stellar ages from measured rotation pe- riods and HR Diagram positions. These relations have few calibrators with known ages for old, long rotation period stars. Read More

Internal stellar magnetic fields are inaccessible to direct observations and little is known about their amplitude, geometry and evolution. We demonstrate that strong magnetic fields in the cores of red giant stars can be identified with asteroseismology. The fields can manifest themselves via depressed dipole stellar oscillation modes, which arises from a magnetic greenhouse effect that scatters and traps oscillation mode energy within the core of the star. Read More