Article
Astronomy & Astrophysics
Igor P. Lopin
Summary: The study investigates axisymmetric magnetohydrodynamic wave modes in the model of a coronal magnetic tube, revealing two families of modes and discussing their properties in twisted and untwisted magnetic fields.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
I Lopin
Summary: This study examines the kink oscillations of a curved coronal slab with finite plasma-beta, simulating a loop arcade. The study finds two surface modes, namely the faster mode and slower mode, in the model. As the internal plasma-beta becomes finite and increases, the phase speed of the faster mode increases, while that of the slower mode decreases.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
I Lopin, I Nagorny
Summary: In this work, we study the impact of curvature on slow-mode oscillations in coronal loop arcade using a theoretical approach. By solving a set of magnetohydrodynamic equations, we derive the dispersion relation that governs the compressible MHD modes in a simple model of curved coronal magnetic structures. Our findings reveal the existence of a band of slow body modes and a single hybrid slow mode in coronal loops under typical circumstances, which exhibit radial kink-like displacements and accompanying longitudinal oscillations. These mode properties can explain the observed Doppler shift, intensity oscillations, and spatial displacements in arcade loops.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Rene Kiefer, Anne-Marie Broomhall
Summary: The study investigates the energy supply rates of solar p modes throughout the solar activity cycle and finds that these rates are anticorrelated with the level of solar activity. Different mode frequency and harmonic degrees show varying strengths of anticorrelation with the solar activity level.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
K. Kosak, R. Kiefer, A-M Broomhall
Summary: This study investigates the variation of pseudo-mode frequencies with solar activity during the solar cycle. The results show that acoustic oscillation frequencies are correlated with the solar cycle, while pseudo-mode frequencies vary in antiphase. The analysis is based on data from different instruments, and the findings reveal differences in the frequency variations between the instruments.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Souvik Das, Ahmed Atteya, Pralay Kumar Karmakar
Summary: A recently developed gravito-electrostatic sheath model is used to study the helioseismic oscillation features in the bi-fluidic solar plasma system. The model reveals the evolution of both dispersive and non-dispersive features of the modified gravito-electrostatic sheath mode fluctuations. Different spectral profiles show important features of the perturbations. The stability of the system depends on various parameters and the dispersive features are more pronounced in the self-gravitational domains.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
David Korda, Michal Svanda
Summary: This study aims to construct a model of flows in average supergranular cells using a consistent time-distance inverse methodology. By analyzing travel-time maps of over 10^4 individual supergranular cells, near-surface divergent horizontal flows and upward vertical flows were discovered. However, systematic errors affected the accuracy of vertical flow estimates, while a longitudinal flow pattern was found to align well with the model of solar rotation in subsurface layers.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
Kyuhyoun Cho, Jongchul Chae, Maria S. Madjarska
Summary: The analysis of umbral flashes in merging sunspots suggests that the subsurface of the umbra is an environment where convection can occur more easily than the convergent interface, supporting the cluster model. Further studies based on umbral velocity oscillations in the lower atmosphere are needed for more concrete results.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
David Korda, Michal Svanda, Thierry Roudier
Summary: The study aims to suppress the negative effects of magnetic fields on solar oscillations and measure plasma properties near active regions. This is done through new averaging geometries, a non-linear approach to travel-time measurements, and a consistent inversion method. The new methodology successfully reconstructs surface horizontal flows near active regions and helps understand the depth structure and physical conditions contributing to the evolution of these regions.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
K. Mandal, S. M. Hanasoge, L. Gizon
Summary: This study successfully extends the methodology to measure even azimuthal orders of Rossby waves in the Sun, adding credibility to the mode-coupling methodology in helioseismology. The results indicate significant power close to the theoretical dispersion relation for sectoral Rossby modes, with maximum power occurring at mode t = 8.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
Dan Yang, Laurent Gizon, Helene Barucq
Summary: This study aims to improve helioseismic holography for detecting active regions on the far side of the Sun and enhancing space weather forecasts. By using a clear problem formulation, an accurate forward solver in the frequency domain, and better understanding of noise properties, the method was improved. Active regions on the far side can be detected with high confidence by measuring and averaging phase shifts between the ingression and egression wave fields. The improvements in active region detection rate and false discovery rate are attributed to the use of a complete Green’s function and all available observations on the front side.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
J. Philidet, L. Gizon
Summary: This study investigates the impact of turbulent motions on the inertial modes in the Sun's convective zone. The results suggest that the stochastic excitation mechanism by turbulent convection explains the observed mode amplitudes reasonably well. However, the complex power spectra of the modes make the interpretation of the observations challenging.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
Yuto Bekki, Robert H. Cameron, Laurent Gizon
Summary: The study focuses on detecting and characterizing modes present in nonlinear numerical simulations of solar convection, highlighting equatorial Rossby modes and columnar convective modes. These modes are compared to linear models and solar observations, providing insights into their amplitudes and impact on heat and angular momentum transport.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
T. Mehta, K. Jain, S. C. Tripathy, R. Kiefer, D. Kolotkov, A-M Broomhall
Summary: In this study, we investigated the relationship between the solar cycle and the presence and periodicity of the Quasi-Biennial Oscillation (QBO). Using helioseismic techniques and solar activity proxies, we found that the presence of the QBO varied significantly between solar cycles. The QBO presence was reduced in Cycle 24 compared to Cycle 23, and it was not dependent on the depth or frequency of the p-mode.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Laurent Gizon, Robert H. Cameron, Yuto Bekki, Aaron C. Birch, Richard S. Bogart, Allan Sacha Brun, Cilia Damiani, Damien Fournier, Laura Hyest, Kiran Jain, B. Lekshmi, Zhi-Chao Liang, Bastian Proxauf
Summary: The study reports observations of the Sun's toroidal modes, with comparisons made to normal modes of a differentially rotating spherical shell to identify high-latitude inertial modes, critical-latitude inertial modes, and equatorial Rossby modes. The high-latitude and critical-latitude modes exhibit maximum kinetic energy density at the base of the convection zone, with the high-latitude modes being baroclinically unstable due to the latitudinal entropy gradient.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
Andrea Miglio, Leo Girardi, Frank Grundahl, Benoit Mosser, Nate Bastian, Angela Bragaglia, Karsten Brogaard, Gael Buldgen, William Chantereau, William Chaplin, Cristina Chiappini, Marc-Antoine Dupret, Patrick Eggenberger, Mark Gieles, Robert Izzard, Daisuke Kawata, Christoffer Karoff, Nadege Lagarde, Ted Mackereth, Demetrio Magrin, Georges Meynet, Eric Michel, Josefina Montalban, Valerio Nascimbeni, Arlette Noels, Giampaolo Piotto, Roberto Ragazzoni, Igor Soszynski, Eline Tolstoy, Silvia Toonen, Amaury Triaud, Fiorenzo Vincenzo
Summary: In the past decade, the Kepler and CoRoT missions have shown the potential of asteroseismology as a powerful tool for testing stellar physics and characterizing stellar properties. Advocating for a new space mission dedicated to collecting high-precision photometric data could lead to breakthroughs in stellar astrophysics.
EXPERIMENTAL ASTRONOMY
(2021)
Article
Astronomy & Astrophysics
Alexander J. Lyttle, Guy R. Davies, Tanda Li, Lindsey M. Carboneau, Ho-Hin Leung, Harry Westwood, William J. Chaplin, Oliver J. Hall, Daniel Huber, Martin B. Nielsen, Sarbani Basu, Rafael A. Garcia
Summary: This study improves the inference of stellar parameters for a sample of Kepler dwarfs and subgiants by applying a new method that includes statistical treatment of stellar helium abundance and mixing-length theory parameters. Despite accounting for uncertainties in helium abundance and mixing-length theory parameters, the method is still able to report statistical uncertainties in mass, radius, and age.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Oliver J. Hall, Guy R. Davies, Jennifer van Saders, Martin B. Nielsen, Mikkel N. Lund, William J. Chaplin, Rafael A. Garcia, Louis Amard, Angela A. Breimann, Saniya Khan, Victor See, Jamie Tayar
Summary: Studies using asteroseismic rotation rates suggest that weakened magnetic braking may occur roughly halfway through a main sequence star's lifetime. The Bayesian mixture model showed that the weakened magnetic braking scenario was 98.4% more likely for the stellar ensemble studied.
Article
Astronomy & Astrophysics
Josefina Montalban, J. Ted Mackereth, Andrea Miglio, Fiorenzo Vincenzo, Cristina Chiappini, Gael Buldgen, Benoit Mosser, Arlette Noels, Richard Scuflaire, Mathieu Vrard, Emma Willett, Guy R. Davies, Oliver J. Hall, Martin Bo Nielsen, Saniya Khan, Ben M. Rendle, Walter E. van Rossem, Jason W. Ferguson, William J. Chaplin
Summary: Using asteroseismology, kinematics, and chemical abundances, precise stellar ages have been estimated for a sample of stars observed by the Kepler space mission. This sample includes some of the oldest stars formed inside the Galaxy as well as stars formed externally and subsequently accreted onto the Milky Way. This provides compelling evidence in favor of models suggesting the Galaxy already had a substantial population of stars before the infall of the satellite galaxy Gaia-Enceladus/Sausage around 10 billion years ago.
Article
Astronomy & Astrophysics
Daniel Huber, Timothy R. White, Travis S. Metcalfe, Ashley Chontos, Michael M. Fausnaugh, Cynthia S. K. Ho, Vincent Van Eylen, Warrick H. Ball, Sarbani Basu, Timothy R. Bedding, Othman Benomar, Diego Bossini, Sylvain Breton, Derek L. Buzasi, Tiago L. Campante, William J. Chaplin, Jorgen Christensen-Dalsgaard, Margarida S. Cunha, Morgan Deal, Rafael A. Garcia, Antonio Garcia Munoz, Charlotte Gehan, Lucia Gonzalez-Cuesta, Chen Jiang, Cenk Kayhan, Hans Kjeldsen, Mia S. Lundkvist, Stephane Mathis, Savita Mathur, Mario J. P. F. G. Monteiro, Benard Nsamba, Jia Mian Joel Ong, Erika Pakstiene, Aldo M. Serenelli, Victor Silva Aguirre, Keivan G. Stassun, Dennis Stello, Sissel Norgaard Stilling, Mark Lykke Winther, Tao Wu, Thomas Barclay, Tansu Daylan, Maximilian N. Gunther, J. J. Hermes, Jon M. Jenkins, David W. Latham, Alan M. Levine, George R. Ricker, Sara Seager, Avi Shporer, Joseph D. Twicken, Roland K. Vanderspek, Joshua N. Winn
Summary: The analysis of the first 20 second cadence light curves obtained by the TESS space telescope during its extended mission showed improved precision compared to 2 minute data for bright stars. This improvement enabled the detection of oscillations in solar analogs and recharacterization of a transiting exoplanet, showing the strong potential of TESS 20 second cadence data for stellar astrophysics and exoplanet science.
ASTRONOMICAL JOURNAL
(2022)
Article
Astronomy & Astrophysics
Michelle L. Hill, Stephen R. Kane, Tiago L. Campante, Zhexing Li, Paul A. Dalba, Timothy D. Brandt, Timothy R. White, Benjamin J. S. Pope, Keivan G. Stassun, Benjamin J. Fulton, Enrico Corsaro, Tanda Li, J. M. Joel Ong, Timothy R. Bedding, Diego Bossini, Derek L. Buzasi, William J. Chaplin, Margarida S. Cunha, Rafael A. Garcia, Sylvain N. Breton, Marc Hon, Daniel Huber, Chen Jiang, Cenk Kayhan, James S. Kuszlewicz, Savita Mathur, Aldo Serenelli, Dennis Stello
Summary: Researchers report new observations of the bright giant star Iota Draconis, aiming to further understand the nature of its planetary companion and the presence of a long-period companion in the system. By observing the star, they were able to constrain its properties and discover an unknown companion.
ASTRONOMICAL JOURNAL
(2021)
Article
Astronomy & Astrophysics
A. Moya, L. M. Sarro, E. Delgado-Mena, W. J. Chaplin, V Adibekyan, S. Blanco-Cuaresma
Summary: Dating stars using chemical abundances is a significant challenge with implications for various astrophysical fields. By employing Bayesian inference techniques and accurate observations, researchers have made progress in estimating the ages of FGK stars. Results show good agreement with other reliable sources and benchmarks, indicating the potential of using chemical abundances for stellar dating.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
Ashley Chontos, Daniel Huber, Travis A. Berger, Hans Kjeldsen, Aldo M. Serenelli, Victor Silva Aguirre, Warrick H. Ball, Sarbani Basu, Timothy R. Bedding, William J. Chaplin, Zachary R. Claytor, Enrico Corsaro, Rafael A. Garcia, Steve B. Howell, Mia S. Lundkvist, Savita Mathur, Travis S. Metcalfe, Martin B. Nielsen, Jia Mian Joel Ong, Zeynep Celik Orhan, Sibel Ortel, Maissa Salama, Keivan G. Stassun, R. H. D. Townsend, Jennifer L. van Saders, Mark Winther, Mutlu Yildiz, R. Paul Butler, C. G. Tinney, Robert A. Wittenmyer
Summary: Asteroseismology of bright stars is crucial for determining their fundamental properties, particularly their ages, and the Kepler Space Telescope has revolutionized this field. By utilizing a combination of astrometry, spectroscopy, and asteroseismology, solar-like oscillations in alpha Men A have been accurately characterized. This discovery presents alpha Men A as a prime target for next-generation direct-imaging missions.
ASTROPHYSICAL JOURNAL
(2021)
Article
Astronomy & Astrophysics
M. S. Cunha, I. W. Roxburgh, V. Aguirre Borsen-Koch, W. H. Ball, S. Basu, W. J. Chaplin, M-J Goupil, B. Nsamba, J. Ong, D. R. Reese, K. Verma, K. Belkacem, T. Campante, J. Christensen-Dalsgaard, M. T. Clara, S. Deheuvels, M. J. P. F. G. Monteiro, A. Noll, R. M. Ouazzani, J. L. Rorsted, A. Stokholm, M. L. Winther
Summary: Asteroseismology is a powerful tool for inferring fundamental stellar properties, with an experiment revealing the accuracy of inferred values for mass, radius, and age. Different inference procedures, physics assumptions, and weighting of constraints were found to significantly impact the results. Only a few frequencies were needed for accurate mass and radius estimates, while at least one l = 2 mode was crucial for age estimates.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
M. B. Nielsen, E. Hatt, W. J. Chaplin, W. H. Ball, G. R. Davies
Summary: The study aims to develop an algorithm that can automatically determine evidence of solar-like oscillations in photometric measurements. By testing observable frequencies and repeating oscillation patterns, the algorithm can effectively differentiate solar-like oscillators from nonoscillators with high accuracy rates.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
Joel C. Zinn, Dennis Stello, Yvonne Elsworth, Rafael A. Garcia, Thomas Kallinger, Savita Mathur, Benoit Mosser, Marc Hon, Lisa Bugnet, Caitlin Jones, Claudia Reyes, Sanjib Sharma, Ralph Schonrich, Jack T. Warfield, Rodrigo Luger, Andrew Vanderburg, Chiaki Kobayashi, Marc H. Pinsonneault, Jennifer A. Johnson, Daniel Huber, Sven Buder, Meridith Joyce, Joss Bland-Hawthorn, Luca Casagrande, Geraint F. Lewis, Andrea Miglio, Thomas Nordlander, Guy R. Davies, Gayandhi De Silva, William J. Chaplin, Victor Silva Aguirre
Summary: This passage presents the third and final data release of the K2 Galactic Archaeology Program, which includes asteroseismic radius and mass coefficients for red giant stars. The data is calibrated using Gaia DR2 and compared to GALAH DR3 spectroscopy. Age-abundance relations and various astronomical phenomena are also discussed.
ASTROPHYSICAL JOURNAL
(2022)
Article
Astronomy & Astrophysics
Rachel Howe, W. J. Chaplin, Y. P. Elsworth, S. J. Hale, M. B. Nielsen
Summary: In this study, we examine the solar cycle variation of power in low-degree helioseismic modes and find that the relationship between mode power and magnetic activity is more complex than previously thought.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Warrick H. Ball, Andrea Miglio, William J. Chaplin, Keivan G. Stassun, Rafael Garcia, Lucia Gonzalez-Cuesta, Savita Mathur, Thierry Appourchaux, Othman Benomar, Derek L. Buzasi, Chen Jiang, Cenk Kayhan, Sibel Ortel, Zeynep Celik Orhan, Mutlu Yildiz, J. M. Joel Ong, Sarbani Basu
Summary: Binary stars can provide important constraints on stellar physics, and the 12 Bootis system is particularly promising. By studying the oscillations and light curves of this system, we have obtained new constraints on its properties.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Emily Hatt, Martin B. Nielsen, William J. Chaplin, Warrick H. Ball, Guy R. Davies, Timothy R. Bedding, Derek L. Buzasi, Ashley Chontos, Daniel Huber, Cenk Kayhan, Yaguang Li, Timothy R. White, Chen Cheng, Travis S. Metcalfe, Dennis Stello
Summary: TESS mission provides photometric light curves for stars across nearly the entire sky, enabling the application of asteroseismology to a pool of potential solar-like oscillators unprecedented in size. The aim of this study is to create a catalogue of solar-like oscillators observed by TESS in the 120-s and 20-s cadence modes, focusing on stars oscillating at frequencies above the TESS 30-min cadence Nyquist frequency. Using a new probabilistic detection algorithm, a catalogue of 4177 solar-like oscillators is produced, reporting the asteroseismic parameters v(max) and Delta v for 98% of the total star count.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
Chen Jiang, Tao Wu, Adina D. Feinstein, Keivan G. Stassun, Timothy R. Bedding, Dimitri Veras, Enrico Corsaro, Derek L. Buzasi, Dennis Stello, Yaguang Li, Savita Mathur, Rafael A. Garcia, Sylvain N. Breton, Mia S. Lundkvist, Przemyslaw J. Mikolajczyk, Charlotte Gehan, Tiago L. Campante, Diego Bossini, Stephen R. Kane, Jia Mian Joel Ong, Mutlu Yildiz, Cenk Kayhan, Zeynep celik Orhan, Sibel Ortel, Xinyi Zhang, Margarida S. Cunha, Bruno Lustosa de Moura, Jie Yu, Daniel Huber, Jian-wen Ou, Robert A. Wittenmyer, Laurent Gizon, William J. Chaplin
Summary: The Transiting Exoplanet Survey Satellite (TESS) mission has detected solar-like oscillations in the giant star HD 76920, allowing for detailed asteroseismic analysis. By utilizing TESS data, improved measurements of the stellar parameters and updated parameters of the planet have been determined. It is confirmed that the planet will be engulfed by the stellar envelope within about 100 Myr.
ASTROPHYSICAL JOURNAL
(2023)
