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14 results on '"Karinkuzhi, Drisya"'

1. From the s -Process to the i -Process: A New Perspective on the Chemical Enrichment of Extrinsic Stars.

Author

Van Eck, Sophie, Giribaldi, Riano, Merle, Thibault, Lambotte, Adrian, Karinkuzhi, Drisya, Goriely, Stéphane, Choplin, Arthur, Storm, Nicholas, Gerber, Jeffrey, Siess, Lionel, Bergemann, Maria, and Jorissen, Alain

Subjects
NUCLEOSYNTHESIS, MIXTURES
Abstract

Separating stars enriched in the s- and r-processes of nucleosynthesis is usually achieved by analyzing the element ratios of s-process elements (like Ba or La) to r-process elements (like Eu). The situation becomes more complex when analyzing CEMP-rs stars, which are carbon-enriched metal-poor objects enriched in a mixture of s- and r-elements. These objects, possibly resulting from the i-process of nucleosynthesis, are notoriously difficult to classify based on elemental ratios. Recent theoretical studies have outlined, however, that the s-, i-, and r-processes produce distinct isotopic mixtures. Here, we propose to analyze a sample of stars known to be enriched in s, r, or r + s elements and to determine the odd-to-even isotopic ratio measured on atomic lines of barium, in order to validate or disprove their assignation. [ABSTRACT FROM AUTHOR]

Published
2024
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2. Asteroseismology of the mild Am δ Sct star HD 118660: TESS photometry and modelling.

Author

Sarkar, Mrinmoy, Joshi, Santosh, Dupret, Marc-Antoine, Trust, Otto, De Cat, Peter, Semenko, Eugene, Lampens, Patricia, Goswami, Aruna, Mkrtichian, David, Karinkuzhi, Drisya, Yakunin, Ilya, and Gupta, Archana

Subjects
STELLAR evolution, TEMPERATURE of stars, ASTEROSEISMOLOGY, PHOTOMETRY, VELOCITY
Abstract

We present the results of an asteroseismic study of HD 118660 (TIC 171729860), being a chemically peculiar (mild Am) star exhibiting |$\delta$| Scuti (⁠|$\delta$|  Sct) pulsations. It is based on the analysis of two sectors of time-series photometry from the space mission TESS (Transiting Exoplanet Survey Satellite) and seismic modelling. It yielded the detection of 15 and 16 frequencies for TESS sectors 23 and 50, respectively. The identified pulsation modes include four radial (⁠|$\ell =0$|⁠) and five dipolar (⁠|$\ell =1$|⁠) ones. The radial modes are overtones with order n ranging from 3 and 6. Such high values of n are theoretically not expected for stars with the effective temperature of HD 118660 (⁠|$T_{\rm eff}\approx 7550\,\rm K$|⁠) located near the red edge of the |$\delta$|  Sct instability strip. To estimate the asteroseismic parameters, we have generated a grid of stellar models assuming a solar metallicity (⁠|$Z=0.014$|⁠) and different values for the convective overshooting parameter (⁠|$0.1\le \alpha _{\rm ov}\le 0.3$|⁠). We conclude that the analysis of the radial modes is insufficient to constrain |$\alpha _{\rm ov}$| and Z for |$\delta$|  Sct stars. The value for the equatorial velocity of HD 118660 derived from the seismic radius and the rotational frequency is consistent with values found in the literature. [ABSTRACT FROM AUTHOR]

Published
2024
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4. Mass–radius relation for magnetized white dwarfs from SDSS.

Author

Karinkuzhi, Drisya, Mukhopadhyay, Banibrata, Wickramasinghe, Dayal, and Tout, Christopher A

Subjects
*WHITE dwarf stars, *MAGNETIC flux density, *SPECTRAL energy distribution, *STELLAR luminosity function, *HR diagrams, *STELLAR magnetic fields, *RADIUS (Geometry)
Abstract

We present the observational mass–radius (M–R) relation for a sample of 47 magnetized white dwarfs (WDs) with the magnetic field strength (B) ranging from 1 to 773 MG, identified from the SDSS data release 7 (DR7). We derive their effective temperature, surface gravity (log g), luminosity, radius, and mass. While atmospheric parameters are derived using a Virtual Observatory Spectral Energy Distribution Analyzer (VOSA), the mass is derived using their location in the HR diagram in comparison with the evolutionary tracks of different masses. We implement this mass measurement instead of a more traditional method of deriving masses from log g , which is unreliable as is based on SED and generates errors from other physical parameters involved. The main disadvantage of this method is that we need to assume a core composition of WDs. As it is complicated to identify the exact composition of these WDs from low-resolution spectra, we use tracks for the masses 0.2 to 0.4 M⊙ assuming a He-core, 0.5 to 1.0 M⊙ assuming CO core, and above M⊙ assuming O–Ne–Mg core. We compare the observed M–R relation with those predicted by the finite temperature model by considering different B , which are well in agreement considering their relatively low-surface fields, ≲109 G. Currently, there is no direct observational detection of magnetized WDs with B > 109 G. We propose that our model can be further extrapolated to higher B , which may indicate the existence of super-Chandrasekhar mass (M > 1.4 M⊙) WDs at higher B. [ABSTRACT FROM AUTHOR]

Published
2024
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5. Binary interaction along the Red Giant Branch: The Barium Star perspective

Author

Escorza, Ana, Siess, Lionel, Karinkuzhi, Drisya, Boffin, Henri M. J., Jorissen, Alain, and Van Winckel, Hans

Subjects
Astrophysics - Solar and Stellar Astrophysics, Astrophysics::Solar and Stellar Astrophysics, FOS: Physical sciences, Astrophysics::Earth and Planetary Astrophysics, Astrophysics::Galaxy Astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysique
Abstract

Barium (Ba) stars form via mass-transfer in binary systems, and can subsequently interact with their white dwarf companion in a second stage of binary interaction. We used observations of main-sequence Ba systems as input for our evolutionary models, and try to reproduce the orbits of the Ba giants. We show that to explain short and sometimes eccentric orbits, additional interaction mechanisms are needed along the RGB., Comment: Proceedings IAU Symposium 343 2 pages, 2 figures

Published
2019

6. The Detailed Science Case for the Maunakea Spectroscopic Explorer, 2019 edition

Author

The MSE Science Team, Babusiaux, Carine, Bergemann, Maria, Burgasser, Adam, Ellison, Sara, Haggard, Daryl, Huber, Daniel, Kaplinghat, Manoj, Li, Ting, Marshall, Jennifer, Martell, Sarah, McConnachie, Alan, Percival, Will, Robotham, Aaron, Shen, Yue, Thirupathi, Sivarani, Tran, Kim-Vy, Yeche, Christophe, Yong, David, Adibekyan, Vardan, Aguirre, Victor Silva, Angelou, George, Asplund, Martin, Balogh, Michael, Banerjee, Projjwal, Bannister, Michele, Barría, Daniela, Battaglia, Giuseppina, Bayo, Amelia, Bechtol, Keith, Beck, Paul G., Beers, Timothy C., Bellinger, Earl P., Berg, Trystyn, Bestenlehner, Joachim M., Bilicki, Maciej, Bitsch, Bertram, Bland-Hawthorn, Joss, Bolton, Adam S., Boselli, Alessandro, Bovy, Jo, Bragaglia, Angela, Buzasi, Derek, Caffau, Elisabetta, Cami, Jan, Carleton, Timothy, Casagrande, Luca, Cassisi, Santi, Catelan, Márcio, Chang, Chihway, Cortese, Luca, Damjanov, Ivana, Davies, Luke J. M., de Grijs, Richard, de Rosa, Gisella, Deason, Alis, di Matteo, Paola, Drlica-Wagner, Alex, Erkal, Denis, Escorza, Ana, Ferrarese, Laura, Fleming, Scott W., Font-Ribera, Andreu, Freeman, Ken, Gänsicke, Boris T., Gabdeev, Maksim, Gallagher, Sarah, Gandolfi, Davide, García, Rafael A., Gaulme, Patrick, Geha, Marla, Gennaro, Mario, Gieles, Mark, Gilbert, Karoline, Gordon, Yjan, Goswami, Aruna, Greco, Johnny P., Grillmair, Carl, Guiglion, Guillaume, Hénault-Brunet, Vincent, Hall, Patrick, Handler, Gerald, Hansen, Terese, Hathi, Nimish, Hatzidimitriou, Despina, Haywood, Misha, Santisteban, Juan V. Hernández, Hillenbrand, Lynne, Hopkins, Andrew M., Howlett, Cullan, Hudson, Michael J., Ibata, Rodrigo, Ilić, Dragana, Jablonka, Pascale, Ji, Alexander, Jiang, Linhua, Juneau, Stephanie, Karakas, Amanda, Karinkuzhi, Drisya, Kim, Stacy Y., Kong, Xu, Konstantopoulos, Iraklis, Krogager, Jens-Kristian, Lagos, Claudia, Lallement, Rosine, Laporte, Chervin, Lebreton, Yveline, Lee, Khee-Gan, Lewis, Geraint F., Lianou, Sophia, Liu, Xin, Lodieu, Nicolas, Loveday, Jon, Mészáros, Szabolcs, Makler, Martin, Mao, Yao-Yuan, Marchesini, Danilo, Martin, Nicolas, Mateo, Mario, Melis, Carl, Merle, Thibault, Miglio, Andrea, Mohammad, Faizan Gohar, Molaverdikhani, Karan, Monier, Richard, Morel, Thierry, Mosser, Benoit, Nataf, David, Necib, Lina, Neilson, Hilding R., Newman, Jeffrey A., Nierenberg, A. M., Nord, Brian, Noterdaeme, Pasquier, O'Dea, Chris, Oshagh, Mahmoudreza, Pace, Andrew B., Palanque-Delabrouille, Nathalie, Pandey, Gajendra, Parker, Laura C., Pawlowski, Marcel S., Peter, Annika H. G., Petitjean, Patrick, Petric, Andreea, Placco, Vinicius, Popović, Luka Č., Price-Whelan, Adrian M., Prsa, Andrej, Ravindranath, Swara, Rich, R. Michael, Ruan, John, Rybizki, Jan, Sakari, Charli, Sanderson, Robyn E., Schiavon, Ricardo, Schimd, Carlo, Serenelli, Aldo, Siebert, Arnaud, Siudek, Malgorzata, Smiljanic, Rodolfo, Smith, Daniel, Sobeck, Jennifer, Starkenburg, Else, Stello, Dennis, Szabó, Gyula M., Szabo, Robert, Taylor, Matthew A., Thanjavur, Karun, Thomas, Guillaume, Tollerud, Erik, Toonen, Silvia, Tremblay, Pier-Emmanuel, Tresse, Laurence, Tsantaki, Maria, Valentini, Marica, Van Eck, Sophie, Variu, Andrei, Venn, Kim, Villaver, Eva, Walker, Matthew G., Wang, Yiping, Wang, Yuting, Wilson, Michael J., Wright, Nicolas, Xu, Siyi, Yildiz, Mutlu, Zhang, Huawei, Zwintz, Konstanze, Anguiano, Borja, Bedell, Megan, Chaplin, William, Collet, Remo, Cuillandre, Jean-Charles, Duc, Pierre-Alain, Flagey, Nicolas, Hermes, JJ, Hill, Alexis, Kamath, Devika, Laychak, Mary Beth, Małek, Katarzyna, Marley, Mark, Sheinis, Andy, Simons, Doug, Sousa, Sérgio G., Szeto, Kei, Ting, Yuan-Sen, Vegetti, Simona, Wells, Lisa, Babas, Ferdinand, Bauman, Steve, Bosselli, Alessandro, Côté, Pat, Colless, Matthew, Comparat, Johan, Courtois, Helene, Crampton, David, Croom, Scott, Davies, Luke, Denny, Kelly, Devost, Daniel, Driver, Simon, Fernandez-Lorenzo, Mirian, Guhathakurta, Raja, Han, Zhanwen, Higgs, Clare, Hill, Vanessa, Ho, Kevin, Hopkins, Andrew, Hudson, Mike, Isani, Sidik, Jarvis, Matt, Johnson, Andrew, Jullo, Eric, Kaiser, Nick, Kneib, Jean-Paul, Koda, Jun, Koshy, George, Mignot, Shan, Murowinski, Rick, Newman, Jeff, Nusser, Adi, Pancoast, Anna, Peng, Eric, Peroux, Celine, Pichon, Christophe, Poggianti, Bianca, Richard, Johan, Salmon, Derrick, Seibert, Arnaud, Shastri, Prajval, Smith, Dan, Sutaria, Firoza, Tao, Charling, Taylor, Edwar, Tully, Brent, van Waerbeke, Ludovic, Vermeulen, Tom, Walker, Matthew, Willis, Jon, Willot, Chris, Withington, Kanoa, International Max Planck Research School for Astronomy and Cosmic Physics (University of Heidelberg), Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS), Center for Astrophysics and Space Sciences [La Jolla] (CASS), University of California [San Diego] (UC San Diego), University of California-University of California, Cognition, Langues, Langage, Ergonomie (CLLE-ERSS), École pratique des hautes études (EPHE)-Université Toulouse - Jean Jaurès (UT2J)-Université Bordeaux Montaigne-Centre National de la Recherche Scientifique (CNRS), Technicolor R & I [Cesson Sévigné], Technicolor, University of Edinburgh, University of Texas-Pan American (UTPA), University of Texas-Pan, Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Max-Planck-Institut für Astrophysik (MPA), Max-Planck-Gesellschaft, Australian National University (ANU), Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7), Max-Planck-Institut für Astronomie (MPIA), Lund Observatory, Lund University [Lund], Anglo-Australian Observatory (AAO), Laboratoire d'Astrophysique de Marseille (LAM), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), Zentrum für Astronomie der Universität Heidelberg (ZAH), Universität Heidelberg [Heidelberg], Department of Physics and Astronomy [London, ON], University of Western Ontario (UWO), National Research Council of Canada (NRC), STScI, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Institute of Astronomy, University of Cambridge [UK] (CAM), Joseph Louis LAGRANGE (LAGRANGE), Université Nice Sophia Antipolis (... - 2019) (UNS), Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Galaxies, Etoiles, Physique, Instrumentation (GEPI), PSL Research University (PSL)-PSL Research University (PSL)-Centre National de la Recherche Scientifique (CNRS), Caltech Department of Astronomy [Pasadena], California Institute of Technology (CALTECH), Département d'Astrophysique (ex SAP) (DAP), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Institut d'Astrophysique de Paris (IAP), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), European Southern Observatory (ESO), Institut de Physique de Rennes (IPR), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS), Lawrence Berkeley National Laboratory [Berkeley] (LBNL), State Key Laboratory of Fine Chemicals, Franche-Comté Électronique Mécanique, Thermique et Optique - Sciences et Technologies (UMR 6174) (FEMTO-ST), Université de Franche-Comté (UFC)-Centre National de la Recherche Scientifique (CNRS)-Ecole Nationale Supérieure de Mécanique et des Microtechniques (ENSMM)-Université de Technologie de Belfort-Montbeliard (UTBM), School of Physics and Astronomy, University of Birmingham [Birmingham], Laboratoire Univers et Particules de Montpellier (LUPM), Université de Montpellier (UM)-Université Montpellier 2 - Sciences et Techniques (UM2)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Department of Physics and Astronomy [Pittsburgh], University of Pittsburgh (PITT), Pennsylvania Commonwealth System of Higher Education (PCSHE)-Pennsylvania Commonwealth System of Higher Education (PCSHE), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Sciences, Philosophie, Histoire (SPHERE UMR 7219), Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Department of Physics and Astronomy [UCLA Los Angeles], University of California [Los Angeles] (UCLA), Institute of Space Sciences [Barcelona] (ICE-CSIC), Spanish National Research Council [Madrid] (CSIC), Stellar Astrophysics Centre [Aarhus] (SAC), Aarhus University [Aarhus], High Speed Networks Laboratory, Dept. of Telecommunications and Media Informatics, Budapest University of Technology and Economics [Budapest] (BME), Laboratoire Interdisciplinaire Carnot de Bourgogne (LICB), Université de Bourgogne (UB)-Centre National de la Recherche Scientifique (CNRS), Institut d'Astrophysique et de Géophysique [Liège], Université de Liège, College of Life Sciences, Peking Univertsity, Department of Mathematics [UCLA], Department of Psychology, St John's University, Canada-France-Hawaii Telescope Corporation (CFHT), National Research Council of Canada (NRC)-Centre National de la Recherche Scientifique (CNRS)-University of Hawai'i [Honolulu] (UH), Institut d'astrophysique spatiale (IAS), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Departamento de FisicaTeorica e IFT-UAM/CSIC, Universidad Autonoma de Madrid (UAM), Institut de Physique Nucléaire de Lyon (IPNL), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Herzberg Institute of Astrophysics, Department of electronic engineering, Chang Gung University, Observatoire astronomique de Strasbourg (ObAS), Université de Strasbourg (UNISTRA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), The Open Group Research Institute (TOGRI), Université Joseph Fourier - Grenoble 1 (UJF), École normale supérieure - Paris (ENS Paris), Laboratoire Astrophysique de Toulouse-Tarbes (LATT), Centre National de la Recherche Scientifique (CNRS)-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées, Observatoire astronomique de Strasbourg (OAS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS), Centre de Physique des Particules de Marseille (CPPM), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Aix Marseille Université (AMU), MSE Science Team, Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Toulouse - Jean Jaurès (UT2J)-Université Bordeaux Montaigne-Centre National de la Recherche Scientifique (CNRS), 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), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Institute of Astronomy [Cambridge], 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), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Université de Technologie de Belfort-Montbeliard (UTBM)-Ecole Nationale Supérieure de Mécanique et des Microtechniques (ENSMM)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC)-Centre National de la Recherche Scientifique (CNRS), Université Montpellier 2 - Sciences et Techniques (UM2)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Sciences, Philosophie, Histoire (SPHERE (UMR_7219)), Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Université Paris sciences et lettres (PSL), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Aix Marseille Université (AMU)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Université de Bourgogne (UB), University of California (UC)-University of California (UC), École Pratique des Hautes Études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Toulouse - Jean Jaurès (UT2J), Université de Toulouse (UT)-Université de Toulouse (UT)-Université Bordeaux Montaigne (UBM)-Centre National de la Recherche Scientifique (CNRS), Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), Universität Heidelberg [Heidelberg] = Heidelberg University, Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-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), Université de Rennes (UR)-Centre National de la Recherche Scientifique (CNRS), Université de Technologie de Belfort-Montbeliard (UTBM)-Ecole Nationale Supérieure de Mécanique et des Microtechniques (ENSMM)-Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Interdisciplinaire Carnot de Bourgogne (ICB), Peking University [Beijing], Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Universidad Autónoma de Madrid (UAM), École normale supérieure - Paris (ENS-PSL), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), and Lebreton, Yveline

Subjects
[PHYS]Physics [physics], Cosmology and Nongalactic Astrophysics (astro-ph.CO), Astrophysics::Instrumentation and Methods for Astrophysics, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics - Astrophysics of Galaxies, [PHYS] Physics [physics], [SDU] Sciences of the Universe [physics], [SDU]Sciences of the Universe [physics], Astrophysics of Galaxies (astro-ph.GA), Astrophysics::Earth and Planetary Astrophysics, Astrophysics - Instrumentation and Methods for Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), Astrophysics::Galaxy Astrophysics, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

(Abridged) The Maunakea Spectroscopic Explorer (MSE) is an end-to-end science platform for the design, execution and scientific exploitation of spectroscopic surveys. It will unveil the composition and dynamics of the faint Universe and impact nearly every field of astrophysics across all spatial scales, from individual stars to the largest scale structures in the Universe. Major pillars in the science program for MSE include (i) the ultimate Gaia follow-up facility for understanding the chemistry and dynamics of the distant Milky Way, including the outer disk and faint stellar halo at high spectral resolution (ii) galaxy formation and evolution at cosmic noon, via the type of revolutionary surveys that have occurred in the nearby Universe, but now conducted at the peak of the star formation history of the Universe (iii) derivation of the mass of the neutrino and insights into inflationary physics through a cosmological redshift survey that probes a large volume of the Universe with a high galaxy density. MSE is positioned to become a critical hub in the emerging international network of front-line astronomical facilities, with scientific capabilities that naturally complement and extend the scientific power of Gaia, the Large Synoptic Survey Telescope, the Square Kilometer Array, Euclid, WFIRST, the 30m telescopes and many more., 9 chapters, 301 pages, 100 figures. This version of the DSC is a comprehensive update of the original version, released in 2016, which can be downloaded at arXiv:1606.00043. A detailed summary of the design of MSE is available in the MSE Book 2018, available at arXiv:1810.08695

Published
2019

7. Research at the Institute of Astronomy and Astrophysics of the Université Libre de Bruxelles

Author

Karinkuzhi, Drisya, Chamel, Nicolas, Goriely, Stéphane, Jorissen, Alain, Pourbaix, Dimitri, Siess, Lionel, and Van Eck, Sophie

Subjects
instrumentation, Engineering, Multidisciplinary, astrophysics, observatoires, business.industry, observatories, Astrophysics::Instrumentation and Methods for Astrophysics, Library science, Astrophysics::Cosmology and Extragalactic Astrophysics, astronomy, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, astronomie, Instrumentation (computer programming), business, Astrophysics::Galaxy Astrophysics, astrophysique
Abstract

Over the years, a coherent research strategy has developed in the field of stellar physics at the Institute of Astronomy and Astrophysics (IAA). It involves observational studies (chemical composition of giant stars, binary properties, tomography of stellar atmospheres) that make use of the large ESO telescopes as well as of other major instruments. The presence of a high-resolution spectrograph on the 3.6-m Devasthal Optical Telescope (DOT) would therefore be highly beneficial to IAA research. These observations are complemented and supported by theoretical studies of mass transfer in binary systems, of standard and non-standard stellar evolution (including the modelling of stellar hydrodynamical nuclear burning for application to certain thermonuclear supernovae) and of nuclear astrophysics (a field in which IAA has been recognized for a long time as an international centre of excellence), including the theory of nucleosynthesis. IAA also addresses the end-points of stellar evolution as it is carrying out research on the compact remnants of stellar evolution of massive stars: neutron stars.

Published
2018
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8. Chemical analysis of three barium stars: HD 51959, HD 88035, and HD 121447.

Author

Karinkuzhi, Drisya, Goswami, Aruna, Sridhar, Navin, Masseron, Thomas, and Purandardas, Meenakshi

Subjects
*ANALYTICAL chemistry, *BARIUM, *STARS, *SPECTRUM analysis, *NITROGEN
Abstract

We present elemental abundance results from high-resolution spectral analysis of three nitrogen-enhanced barium stars. The analysis is based on spectra obtained with the fibre-fed extended range optical spectrograph attached to 1.52 m telescope at European Southern Observatory, Chile. The spectral resolution is R  ∼ 48,000 and the spectral coverage spans from 3500 to 9000Å . For the objects HD 51959 and HD 88035, we present the first-time abundance analyses results. Although a few studies are available in literature on the object HD 121447, the results are significantly different from each other. We have therefore carried out a detailed chemical composition study for this object based on a high-resolution spectrum with high S/N ratio, for a better understanding of the origin of the abundance patterns observed in this star. Stellar atmospheric parameters, the effective temperature, surface gravity, microturbulence, and metallicity of the stars are determined from the local thermodynamic equilibrium analysis using model atmospheres. The metallicities of HD 51959 and HD 88035 are found to be near-solar; they exhibit enhanced abundances of neutron-capture elements. HD 121447 is found to be moderately metal-poor with [Fe/H] = −0.65. While carbon is near-solar in the other two objects, HD 121447 shows carbon enhancement at a level, [C/Fe] = 0.82. Neutron-capture elements are highly enhanced with [X/Fe] >  2 (X: Ba, La, Pr, Nd, Sm) in this object. The α- and iron-peak elements show abundances very similar to field giants with the same metallicity. From kinematic analysis all the three objects are found to be members of thin disc population with a high probability of 0.99, 0.99, and 0.92 for HD 51959, HD 88035, and HD 121447, respectively. [ABSTRACT FROM AUTHOR]

Published
2018
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9. Abundance analysis of s-process enhanced barium stars.

Author

Mahanta, Upakul, Karinkuzhi, Drisya, Goswami, Aruna, and Duorah, Kalpana

Subjects
*PECULIAR stars, *BARIUM, *NEUTRON capture, *NUCLEOSYNTHESIS, *WAVELENGTHS, *THERMODYNAMIC equilibrium
Abstract

Detailed chemical composition studies of stars with enhanced abundances of neutron-capture elements can provide observational constraints for neutron-capture nucleosynthesis studies and clues for understanding their contribution to the Galactic chemical enrichment. We present abundance results from high-resolution spectral analyses of a sample of four chemically peculiar stars characterized by s-process enhancement. High-resolution spectra (R ~ 42 000) of these objects spanning a wavelength range from 4000 to 6800 Å are taken from the ELODIE archive. We have estimated the stellar atmospheric parameters, the effective temperature Teff, the surface gravity log g and metallicity [Fe/H] from local thermodynamic equilibrium analysis using model atmospheres. We report estimates of elemental abundances for several neutroncapture elements, Sr, Y, Zr, Ba, La, Ce, Pr, Nd, Sm, Eu and Dy. While HD 49641 and HD 58368 show [Ba/Fe] ≽ 1.16, the other two objects HD 119650 and HD 191010 are found to be mild barium stars with [Ba/Fe] ~ 0.4. The derived abundances of the elements are interpreted on the basis of existing theories for understanding their origin and evolution. [ABSTRACT FROM AUTHOR]

Published
2016
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10. Subaru/HDS study of CH stars: elemental abundances for stellar neutron-capture process studies.

Author

Goswami, Aruna, Aoki, Wako, and Karinkuzhi, Drisya

Subjects
N stars, SPECTRUM analysis, STARS, THERMODYNAMIC equilibrium, NEUTRON capture, HEAVY elements
Abstract

A comprehensive abundance analysis providing rare insight into the chemical history of lead stars is still lacking.We present results from high-resolution (R ∼ 50 000) spectral analyses of three CH stars, HD 26, HD 198269 and HD 224959, and, a carbon star with a dusty envelope, HD 100764. Previous studies on these objects are limited by both resolution and wavelength regions and the results differ significantly from each other.We have undertaken to reanalyse the chemical composition of these objects based on high-resolution Subaru spectra covering the wavelength regions 4020-6775 Å. Considering local thermodynamic equilibrium and using model atmospheres, we have derived the stellar parameters, the effective temperatures Teff, surface gravities log g, and metallicities [Fe/H] for these objects. The derived parameters for HD 26, HD 100764, HD 198269 and HD 224959 are (5000, 1.6, -1.13), (4750, 2.0 -0.86), (4500, 1.5, -2.06) and (5050, 2.1, -2.44), respectively. The stars are found to exhibit large enhancements of heavy elements relative to iron in conformity to previous studies. Large enhancement of Pb with respect to iron is also confirmed. Updates on the elemental abundances for several s-process elements (Y, Zr, La, Ce, Nd, Sm and Pb) along with the first-time estimates of abundances for a number of other heavy elements (Sr, Ba, Pr, Eu, Er and W) are reported. Our analysis suggests that neutron-capture elements in HD 26 primarily originate in the s-process while the major contributions to the abundances of neutron-capture elements in the more metal-poor objects HD 224959 and HD 198269 are from the r-process, possibly from materials that are pre-enriched with products of the r-process. [ABSTRACT FROM AUTHOR]

Published
2016
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11. Chemical analysis of CH stars - II. Atmospheric parameters and elemental abundances.

Author

Karinkuzhi, Drisya and Goswami, Aruna

Subjects
*COSMIC abundances, *GRAVITY, *THERMODYNAMIC equilibrium, *RADIAL velocity of stars, *ANALYTICAL chemistry, *PARAMETERS (Statistics)
Abstract

We present detailed chemical analyses for a sample of 12 stars selected from the CH star catalogue of Bartkevicius. The sample includes two confirmed binaries, four objects that are known to show radial velocity variations and the rest with no information on the binary status. A primary objective is to examine if all these objects exhibit chemical abundances characteristics of CH stars, based on detailed chemical composition study using high-resolution spectra. We have used high-resolution (R ~ 42 000) spectra from the ELODIE archive. These spectra cover 3900 to 6800 Å in the wavelength range. We have estimated the stellar atmospheric parameters, the effective temperature Teff, the surface gravity log g, and metallicity [Fe/H] from local thermodynamic equilibrium analysis using model atmospheres. Estimated temperatures of these objects cover a wide range from 4200 to 6640 K, the surface gravity from 0.6 to 4.3 and metallicity from - 0.13 to - 1.5. We report updates on elemental abundances for several heavy elements, Sr, Y, Zr, Ba, La, Ce, Pr, Nd, Sm, Eu and Dy. For the object HD 89668, we present the first abundance analyses results. Enhancement of heavy elements relative to Fe, a characteristic property of CH stars is evident from our analyses in the case of four objects, HD 92545, HD 104979, HD 107574 and HD 204613. A parametric-model-based study is performed to understand the relative contributions from the s- and r-process to the abundances of the heavy elements. [ABSTRACT FROM AUTHOR]

Published
2015
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12. The CH fraction of carbon stars at high Galactic latitudes.

Author

Goswami, Aruna, Karinkuzhi, Drisya, and Shantikumar, N. S.

Subjects
*GALACTIC center, *TEMPERATURE of stars, *ASTRONOMICAL instruments, *ASTRONOMICAL photography, *ASTRONOMICAL observatories
Abstract

CH stars form a distinct class of objects with characteristic properties like iron deficiency, enrichment of carbon and overabundance of heavy elements. These properties can provide strong observational constraints for the theoretical computation of nucleosynthesis at low metallicity. An important issue is the relative surface density of CH stars, which can provide valuable input to our understanding of the role of low- to intermediate-mass stars in early Galactic chemical evolution. Spectroscopic characterization provides an effective way of identifying CH stars. The present analysis aims at a quantitative assessment of the fraction of CH stars in a sample using a set of spectral classification criteria. The sample consists of 92 objects selected from a collection of candidate faint high-latitude carbon stars from the Hamburg/ESO survey. Medium-resolution spectra for these objects were obtained using the Optomechanics Research (OMR) spectrograph at the Vainu Bappu Observatory (VBO), Kavalur and the Himalaya Faint Object Spectrograph (HFOSC) at the Himalayan Chandra Telescope (HCT), Indian Astronomical Observatory, Hanle, during 2007–2009, spanning a wavelength range 3800–6800 Å. Spectral analysis shows 36 of the 92 objects to be potential CH stars; combined with our earlier studies this implies ∼37 per cent (of 243 objects) as the CH fraction. We present spectral descriptions of the newly identified CH star candidates. Estimated effective temperatures, 12C/13C isotopic ratios and their locations on the two-colour versus plot are used to support their identification. [ABSTRACT FROM AUTHOR]

Published
2010
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