Article
Astronomy & Astrophysics
M. Giarrusso, M. Cecconi, R. Cosentino, M. Munari, A. Ghedina, F. Ambrosino, W. Boschin, F. Leone
Summary: In this study, the rotational periods of magnetic chemically peculiar stars of the main sequence were determined by measuring the variability of the integrated magnetic field modulus. New data on the periods of these stars were obtained, and a clear decrease in the field modulus of gamma Equ was observed.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Chris Koen, Cole Johnston
Summary: Theta Car is a bright and well-studied B0 type star in a close binary system with an unseen companion, which has been extensively characterized at multiple wavelengths. Recent observations using the NASA TESS satellite show that the photometric variability of the star may be associated with surface brightness inhomogeneities.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
O. Kobzar, V Khalack, D. Bohlender, G. Mathys, M. E. Shultz, D. M. Bowman, E. Paunzen, C. Lovekin, A. David-Uraz, J. Sikora, P. Lampens, O. Richard
Summary: This study used TESS data to investigate the rotational periods of chemically peculiar stars, and found that the critical rotational fractions decrease with stellar age.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
L. Freour, C. Neiner, J. D. Landstreet, C. P. Folsom, G. A. Wade
Summary: We conducted a spectropolarimetric analysis of the hot star V352 Peg. The analysis showed that the star is a chemically peculiar Bp star with overabundances of iron peak elements and underabundance of He and O. We detected a magnetic field in V352 Peg and determined its geometrical configuration through modelling and Zeeman-Doppler Imaging.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Eugene Semenko, Iosif Romanyuk, Ilya Yakunin, Dmitry Kudryavtsev, Anastasiya Moiseeva
Summary: We conducted a spectropolarimetric survey of 56 chemically peculiar (CP) stars in the Orion OB1 association and identified 31 magnetic stars. We found that the percentage of magnetic CP stars and the strength of their magnetic fields decrease with age. The average longitudinal magnetic field in the young subgroup OB1b is nearly three times stronger than in the older subgroups OB1a and OB1c. In the Orion Nebula, only 20% of CP stars have a magnetic field, which differs significantly from the nearby subgroup OB1c with 83% magnetic CP stars.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Z. Keszthelyi, A. de Koter, Y. Gotberg, G. Meynet, S. A. Brands, V Petit, M. Carrington, A. David-Uraz, S. T. Geen, C. Georgy, R. Hirschi, J. Puls, K. J. Ramalatswa, M. E. Shultz, A. ud-Doula
Summary: Magnetic fields have significant impact on the evolutionary models of massive stars, affecting mass-loss quenching, magnetic braking, and angular momentum transport. In this study, we use the MESA software to compute a grid of stellar structure and evolution models, taking into account the effects of surface fossil magnetic fields. By comparing the models with observations, we quantify the influence of different initial field strengths on the classification of stars and find that chemical mixing is less efficient in magnetic models due to rapid spin-down. We recommend comparing these models with spectropolarimetric and spectroscopic observations to further validate and constrain the magnetic field models.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Z. Keszthelyi, G. Meynet, F. Martins, A. de Koter, A. David-Uraz
Summary: tau Sco is a magnetic B-type star with surprising characteristics such as slow rotation and nitrogen excess. To reconcile its properties with single-star models, an increase in the efficiency of rotational mixing and magnetic braking is necessary.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
J. Labadie-Bartz, S. Huemmerich, K. Bernhard, E. Paunzen, M. E. Shultz
Summary: This study investigates the photometric variability of 1002 magnetic chemically peculiar (mCP) stars, determines their rotational periods, and identifies interesting objects for further studies. The results show that the rotation periods of the stars are related to their evolutionary stages, which supports the assumption of angular momentum conservation during the main-sequence evolution.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
Marcin Hajduk, Paolo Leto, Harish Vedantham, Corrado Trigilio, Marijke Haverkorn, Timothy Shimwell, Joseph R. Callingham, Glenn J. White
Summary: Chemically peculiar stars are upper main sequence stars with anomalies in their optical spectra, indicating peculiar chemical abundances of certain elements. Some of them exhibit strong magnetic fields, leading to non-thermal radio and X-ray emission from electrons in the ionising stellar wind traveling in the magnetosphere. Using LOFAR, radio emission from chemically peculiar stars was constrained in the frequency band 120-168 MHz, with results showing lower incidence rates at these frequencies.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
S. P. Owocki, M. E. Shultz, A. ud-Doula, P. Chandra, B. Das, P. Leto
Summary: Magnetic B-stars exhibit circularly polarized radio emission that is related to magnetic field strength and stellar rotation rate. The acceleration of energetic electrons that emit the radio emission is found to be driven by centrifugal breakout (CBO) driven magnetic reconnection, challenging the conventional paradigm. This finding has significant implications for studying the magnetic field and rotation as well as other observed characteristics of B-stars.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Adam Griffiths, Patrick Eggenberger, Georges Meynet, Facundo Moyano, Miguel-A Aloy
Summary: This study explores the effects of the magneto-rotational instability (MRI) on the evolution of massive stars. The results show that the activation of MRI is highly sensitive to the treatment of meridional circulation and the existence of chemical gradients. The MRI efficiently transports matter and angular momentum, leading to noticeable differences in rotation rates and chemical structure of stars.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
S. K. Lander, P. Haensel, B. Haskell, J. L. Zdunik, M. Fortin
Summary: The study explores the thermal and magnetic field structure of a late-stage proto-neutron star, establishing a simplified equation of state for hot neutron stars and solving the stellar equilibrium equations numerically. The ellipticity increases with temperature for a fixed magnetic field strength, and the Keplerian velocity is considerably lower for hotter stars. Magnetic fields stronger than around 10^14 G have qualitatively similar equilibrium states in both hot and cold neutron stars, with the poloidal field component dominating over the toroidal one.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
M. P. Roriz, C. B. Pereira, S. Junqueira, M. Lugaro, N. A. Drake, C. Sneden
Summary: We present detailed chemical compositions of four chemically peculiar stars on the first-ascent red giant branch, which lack high spectral resolution comprehensive analyses. These stars, BD+03 degrees 2688, HE 0457-1805, HE 1255-2324, and HE 2207-1746, exhibit a range in Galactic population membership with metallicities of [Fe/H] = -1.21, -0.19, -0.31, and -0.55, respectively. We obtained elemental abundances for 28 elements, including CNO group and C-12/C-13 ratios, as well as novel results for the heavy elements tungsten and thallium. All four stars show significant enhancements of neutron-capture elements, indicating enrichments from the slow neutron capture (s-process).
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
E. Paunzen, M. Prisegen
Summary: In this study, the possibility of detecting the characteristic 520 nm flux depression of magnetic chemically peculiar (mCP) stars using low-resolution BP/RP spectra was investigated. The results indicate that mCP stars can be clearly distinguished from normal-type objects, and the BP/RP spectra are qualified for efficiently searching for and detecting mCP stars.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
Umin Lee
Summary: The study focuses on overstable convective (OsC) modes in stars, finding that as rotation frequency increases, OsC modes tend towards stabilization and excite envelope g modes, aiding stellar rotation and maintaining low core rotation frequency.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Kevin France, Brian Fleming, Arika Egan, Jean-Michel Desert, Luca Fossati, Tommi T. Koskinen, Nicholas Nell, Pascal Petit, Aline A. Vidotto, Matthew Beasley, Nicholas DeCicco, Aickara Gopinathan Sreejith, Ambily Suresh, Jared Baumert, P. Wilson Cauley, Carolina Villarreal D'Angelo, Keri Hoadley, Robert Kane, Richard Kohnert, Julian Lambert, Stefan Ulrich
Summary: Atmospheric escape is a fundamental process that affects the structure and evolution of planets. The Colorado Ultraviolet Transit Experiment (CUTE) is a CubeSat mission designed to study the extended atmospheres of nearby planets using near-ultraviolet stellar brightness distribution. CUTE carries a magnifying near-ultraviolet spectrograph and has been conducting transit spectroscopy survey since its launch in September 2021. This paper presents the mission details and initial on-orbit science observations, demonstrating the potential of small satellites in this type of research.
ASTRONOMICAL JOURNAL
(2023)
Article
Astronomy & Astrophysics
Michel Rieutord, Pascal Petit, Daniel Reese, Torsten Bohm, Arturo Lopez Ariste, Giovanni M. M. Mirouh, Armando Domiciano de Souza
Summary: This study investigates the effect of rapid rotation on the stellar evolution of early-type stars and provides observational evidence of the presence of gravito-inertial waves and acoustic waves on the surface of the nearby star Altair.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
Alexis Heitzmann, George Zhou, Samuel N. Quinn, Chelsea X. Huang, Jiayin Dong, L. G. Bouma, Rebekah I. Dawson, Stephen C. Marsden, Duncan Wright, Pascal Petit, Karen A. Collins, Khalid Barkaoui, Robert A. Wittenmyer, Edward Gillen, Rafael Brahm, Melissa Hobson, Coel Hellier, Carl Ziegler, Cesar Briceno, Nicholas Law, Andrew W. Mann, Steve B. Howell, Crystal L. Gnilka, Colin Littlefield, David W. Latham, Jack J. Lissauer, Elisabeth R. Newton, Daniel M. Krolikowski, Ronan Kerr, Rayna Rampalli, Stephanie T. Douglas, Nora L. Eisner, Nathalie Guedj, Guoyou Sun, Martin Smit, Marc Huten, Thorsten Eschweiler, Lyu Abe, Tristan Guillot, George Ricker, Roland Vanderspek, Sara Seager, Jon M. Jenkins, Eric B. Ting, Joshua N. Winn, David R. Ciardi, Andrew M. Vanderburg, Christopher J. Burke, David R. Rodriguez, Tansu Daylan
Summary: We report the discovery of a Jovian planet, TOI-4562b, orbiting a young F7V-type star. This planet has an unusually long orbital period and substantial eccentricity. By observing this planet through TESS, we were able to measure its period accurately. Follow-up photometry and spectroscopy measurements provided the radius and mass of TOI-4562b.
ASTRONOMICAL JOURNAL
(2023)
Article
Astronomy & Astrophysics
J. Labadie-Bartz, S. Huemmerich, K. Bernhard, E. Paunzen, M. E. Shultz
Summary: This study investigates the photometric variability of 1002 magnetic chemically peculiar (mCP) stars, determines their rotational periods, and identifies interesting objects for further studies. The results show that the rotation periods of the stars are related to their evolutionary stages, which supports the assumption of angular momentum conservation during the main-sequence evolution.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
A. Carmona, X. Delfosse, S. Bellotti, P. Cortes-Zuleta, M. Ould-Elhkim, N. Heidari, L. Mignon, J. F. Donati, C. Moutou, N. Cook, E. Artigau, P. Fouque, E. Martioli, C. Cadieux, J. Morin, T. Forveille, I. Boisse, G. Hebrard, R. F. Diaz, D. Lafreniere, F. Kiefer, P. Petit, R. Doyon, L. Acuna, L. Arnold, X. Bonfils, F. Bouchy, V. Bourrier, S. Dalal, M. Deleuil, O. Demangeon, X. Dumusque, N. Hara, S. Hoyer, O. Mousis, A. Santerne, D. Segrasan, M. Stalport, S. Udry
Summary: The periodic variability of the optical radial velocity of Gl 388 is found to be caused by stellar activity rather than a co-rotating planet, as demonstrated by near-infrared measurements.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
P. Fouque, E. Martioli, J. -F. Donati, L. T. Lehmann, B. Zaire, S. Bellotti, E. Gaidos, J. Morin, C. Moutou, P. Petit, S. H. P. Alencar, L. Arnold, E. Artigau, T. -Q. Cang, A. Carmona, N. J. Cook, P. Cortes-Zuleta, P. I. Cristofari, X. Delfosse, R. Doyon, G. Hebrard, L. Malo, C. Reyle, C. Usher
Summary: This study measured the rotation periods of 43 quiet M dwarfs using circular polarization in near-infrared spectral lines and compared the results with other methods. By analyzing Stokes V spectropolarimetric sequences, the longitudinal magnetic field was derived for each star, and Gaussian process regression was applied to determine the rotation period. The study successfully obtained rotation periods for 27 stars, including 8 previously unknown periods. The results demonstrate the importance of near-infrared spectropolarimetry for measuring rotation periods, even for magnetically quiet stars. Additionally, the ages of 20 stars were calculated using gyrochronology.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
P. Cortes-Zuleta, I. Boisse, B. Klein, E. Martioli, P. I. Cristofari, A. Antoniadis-Karnavas, J. -f. Donati, X. Delfosse, C. Cadieux, N. Heidari, E. Artigau, S. Bellotti, X. Bonfils, A. Carmona, N. J. Cook, R. F. Diaz, R. Doyon, P. Fouque, C. Moutou, P. Petit, T. Vandal, L. Acuna, L. Arnold, N. Astudillo-Defru, V. Bourrier, F. Bouchy, R. Cloutier, S. Dalal, M. Deleuil, O. D. S. Demangeon, X. Dumusque, T. Forveille, J. Gomes da Silva, N. Hara, G. Hebrard, S. Hoyer, G. Hussain, F. Kiefer, J. Morin, A. Santerne, N. C. Santos, D. Segransan, M. Stalport, S. Udry
Summary: The study aims to characterize the magnetic field and stellar activity of the early, moderately active M dwarf Gl 205 in the optical and near-infrared domains. The results show that the RV variations observed in Gl 205 are due to stellar activity, with different expressions in the optical and NIR. Spectropolarimetry is the best technique to constrain the stellar rotation period over standard activity indicators for moderately active M dwarfs.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
J-F Donati, P. Cristofari, B. Finociety, B. Klein, C. Moutou, E. Gaidos, C. Cadieux, E. Artigau, A. C. M. Correia, G. Boue, N. J. Cook, A. Carmona, L. T. Lehmann, J. Bouvier, E. Martioli, J. Morin, P. Fouque, X. Delfosse, R. Doyon, G. Hebrard, S. H. P. Alencar, J. Laskar, L. Arnold, P. Petit, A. Kospal, A. Vidotto, C. P. Folsom
Summary: In this paper, the authors analyze the near-infrared spectropolarimetric and velocimetric data of the M dwarf star AU Mic collected from 2019 to 2022. They find that the large- and small-scale magnetic fields of AU Mic show modulation with the stellar rotation period and evolve on a timescale of months. The small-scale field reaches a strength of 2.61 +/- 0.05 kG, while the large-scale field has an average intensity of 550 +/- 30 G and is mainly poloidal and axisymmetric. They also detect the radial velocity signatures of transiting planets b and c, as well as a new candidate planet e with a period near the 4:1 resonance with b.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
S. C. Marsden, D. Evensberget, E. L. Brown, C. Neiner, J. M. Seach, J. Morin, P. Petit, S. Jeffers, C. P. Folsom
Summary: This paper investigates the magnetic field of the mature F7V primary star in the bright chi Draconis system. Observations and analysis reveal that the magnetic field of chi Dra A is relatively stable over a 5-year timespan, with no polarity reversals. Simulations also show that the stellar wind from chi Dra A has a mass-loss rate 3-6 times higher and an angular momentum loss rate 3-4 times higher than the current solar value.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
I. D. Berry, M. E. Shultz, S. P. Owocki, A. ud-Doula
Summary: Early-type B stars with strong magnetic fields and rapid rotation form centrifugal magnetospheres. These magnetospheres can become optically thick enough for emission to occur via electron scattering. The magnetic and rotational properties of these stars can be inferred by comparing photometric modelling with spectropolarimetry data, but there are discrepancies between expected and observed values for optical depth.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
P. Cristofari, J-F Donati, C. P. Folsom, T. Masseron, P. Fouque, C. Moutou, E. Artigau, A. Carmona, P. Petit, X. Delfosse, E. Martioli
Summary: We present a new method for characterizing atmospheric parameters and magnetic properties of M dwarfs using high-resolution near-IR spectra recorded with SPIRou. Our analysis relies on fitting synthetic spectra computed from MARCS model atmospheres to selected spectral lines sensitive and insensitive to magnetic fields. We introduce a new code, ZeeTurbo, which includes the Zeeman effect and polarized radiative transfer capabilities.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
O. Kochukhov, H. Gursoytrak Mutlay, A. M. Amarsi, P. Petit, I Mutlay, B. Gurol
Summary: In this study, we observed and characterized the surface structure of 45 Her, a weak-field Ap star, to better understand the origin of magnetic fields and chemical spot formation. With the help of Zeeman Doppler imaging, we found that despite its weak magnetic field, 45 Her exhibits surface chemical inhomogeneities. We also discovered that chemical spot formation does not necessarily require strong magnetic fields and that the stellar structure and global field can remain stable for sub-100 G field strengths contrary to theoretical predictions.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
S. Bellotti, J. Morin, L. T. Lehmann, C. P. Folsom, G. A. J. Hussain, P. Petit, J. -f. Donati, A. Lavail, A. Carmona, E. Martioli, B. Romano Zaire, E. Alecian, C. Moutou, P. Fouque, S. Alencar, E. Artigau, I. Boisse, F. Bouchy, C. Cadieux, R. Cloutier, N. J. Cook, X. Delfosse, R. Doyon, G. Hebrard, O. Kochukhov, G. A. Wade
Summary: This study aims to monitor the evolution of the large-scale magnetic field of the active M dwarf AD Leo. It found evidence of a long-term evolution of the magnetic field and suggests that low-mass M dwarfs can undergo magnetic cycles.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
A. G. Sreejith, Kevin France, Luca Fossati, Tommi T. Koskinen, Arika Egan, P. Wilson Cauley, Patricio. E. Cubillos, S. Ambily, Chenliang Huang, Panayotis Lavvas, Brian T. Fleming, Jean-Michel Desert, Nicholas Nell, Pascal Petit, Aline Vidotto
Summary: Ultraviolet observations of ultrahot Jupiters provide an opportunity to study atmospheric escape and its impact on their upper atmosphere. The first near-ultraviolet observations of WASP-189b using the Colorado Ultraviolet Transit Experiment (CUTE) revealed the presence of strong metal lines and an extended, hot upper atmosphere. The results indicate a higher upper atmospheric temperature than predicted by current models.
ASTROPHYSICAL JOURNAL LETTERS
(2023)
Article
Astronomy & Astrophysics
J. -d. do Nascimento Jr, S. A. Barnes, S. H. Saar, G. F. Porto de Mello, J. C. Hall, F. Anthony, L. de Almeida, E. N. Velloso, J. S. da Costa, P. Petit, A. Strugarek, B. J. Wargelin, M. Castro, K. G. Strassmeier, A. S. Brun
Summary: Studying the magnetic activity of stars similar to the Sun helps us understand solar magnetism, space weather, and dynamos of other cool stars. We found that the solar twin 18 Scorpii has a longer activity cycle of 15 years, compared to the solar cycle. This suggests that 18 Scorpii may be a magnetic proxy for a younger Sun, providing important data for testing dynamo theory and magnetic evolution of low-mass stars.
ASTROPHYSICAL JOURNAL
(2023)