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
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
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
S. N. Breton, R. A. Garcia, J. Ballot, V Delsanti, D. Salabert
Summary: This article introduces the peakbagging methods for extracting stellar oscillation mode parameters and presents a new Python 3 open-source MCMC framework called apollinaire. The apollinaire module allows for the analysis of helio- and asteroseismic observations and demonstrates its precision and reliability through comparisons with other peakbagging codes.
ASTRONOMY & ASTROPHYSICS
(2022)
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
F. Kahraman Alicavus, G. Handler, F. Alicavus, P. De Cat, T. R. Bedding, P. Lampens, O. Ekinci, D. Gumus, F. Leone
Summary: The study of the photometric and spectroscopic properties of the system revealed the presence of mass transfer with mass loss potentially occurring through a hotspot and stellar winds. Most pulsation frequencies were found to originate from the primary component, suggesting it is a tidally tilted pulsator.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Daniel R. Hey, Angela Kochoska, Richard Monier, Oleg Kochukhov, Cole Johnston, Timothy R. Bedding, Simon J. Murphy, Michael Abdul-Masih, John Southworth, Mads Fredslund Andersen, Frank Grundahl, Pere L. Palle
Summary: This study analyzes the eclipsing single-lined spectroscopic binary system a Dra, determining parameters for both primary and secondary components, as well as performing an abundance analysis of the primary star for 21 chemical elements. The results provide valuable insights into the physical characteristics and chemical composition of this binary system.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
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
Tanda Li, Yaguang Li, Shaolan Bi, Timothy R. Bedding, Guy Davies, Minghao Du
Summary: This paper presents a correction to the scaling relations for red giant stars using model-based masses and radii, and calibrates new scaling relations based on observed and model-inferred parameters.
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
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
Jose Vines, James S. Jenkins, Zaira Berdinas, Maritza G. Soto, Matias R. Diaz, Douglas R. Alves, Mikko Tuomi, Robert A. Wittenmyer, Jerome Pitogo de Leon, Pablo Pena, Jack J. Lissauer, Sarah Ballard, Timothy Bedding, Brendan P. Bowler, Jonathan Horner, Hugh R. A. Jones, Stephen R. Kane, John Kielkopf, Peter Plavchan, Avi Shporer, C. G. Tinney, Hui Zhang, Duncan J. Wright, Brett Addison, Matthew W. Mengel, Jack Okumura, Anya Samadi-Ghadim
Summary: Very little is known about the young planet population due to the challenging detection caused by stellar activity and fast rotation. However, a new mini-Neptune planet has been characterized orbiting a bright and nearby K2 dwarf star, HD 18599. The planet has a high density and is the first young planet of its type in the Neptune Desert.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Tiago L. Campante, Tanda Li, J. M. Joel Ong, Enrico Corsaro, Margarida S. Cunha, Timothy R. Bedding, Diego Bossini, Sylvain N. Breton, Derek L. Buzasi, William J. Chaplin, Morgan Deal, Rafael A. Garcia, Michelle L. Hill, Marc Hon, Daniel Huber, Chen Jiang, Stephen R. Kane, Cenk Kayhan, James S. Kuszlewicz, Jorge Lillo-Box, Savita Mathur, Mario J. P. F. G. Monteiro, Filipe Pereira, Nuno C. Santos, Aldo Serenelli, Dennis Stello
Summary: Asteroseismology is being used to study red giant host stars and their planetary systems. The authors conducted asteroseismic modeling of two evolved red giant branch (RGB) host stars and a benchmark star using data from the Kepler and TESS missions. They found that including different sets of observed modes as seismic constraints improved the precision of the stellar parameters, and that the choice of atmospheric physics can affect the results of seismic modeling.
ASTRONOMICAL JOURNAL
(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)
Article
Astronomy & Astrophysics
Timothy R. Bedding, Simon J. Murphy, Courtney Crawford, Daniel R. Hey, Daniel Huber, Hans Kjeldsen, Yaguang Li, Andrew W. Mann, Guillermo Torres, Timothy R. White, George Zhou
Summary: We studied 89 A-and F-type members of the Pleiades open cluster, including five escaped members. Rotational velocities and pulsations were observed, confirming the broadening effect of stellar rotation on the main sequence and the high proportion of d Scuti pulsations in the cluster. The characteristics of the pulsation spectra were varied and showed no correlation with stellar temperature, challenging the existence of a useful nmax relation for young main-sequence stars.
ASTROPHYSICAL JOURNAL LETTERS
(2023)
Article
Astronomy & Astrophysics
Yaguang Li, Timothy R. Bedding, Dennis Stello, Daniel Huber, Marc Hon, Meridith Joyce, Tanda Li, Jean Perkins, Timothy R. White, Joel C. Zinn, Andrew W. Howard, Howard Isaacson, Daniel R. Hey, Hans Kjeldsen
Summary: In asteroseismology, the surface effect is a disparity between observed and modelled frequencies in stars, caused by improper modelling of surface layers. We parameterize the correction as a function of surface gravity, effective temperature, and metallicity, and determine it by fitting a range of stars. Applying this correction improves parameter estimations and brings asteroseismic properties in agreement with those determined from eclipsing binaries.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Yingxiang Wang, Tanda Li, Shaolan Bi, Timothy R. Bedding, Yaguang Li
Summary: This paper presents the estimated stellar parameters of 1153 red giant branch stars using asteroseismic modeling. By utilizing various data sources and observed constraints, the precision of fundamental stellar parameters has been significantly improved. The results provide the best-characterized large sample of red giant stars to date, with important findings on seismic scaling relations and the surface term on the red giant branch.
ASTROPHYSICAL JOURNAL
(2023)