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相关论文: A magnetic field evolution scenario for brown dwar…

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With the discovery of the companions of 51 Peg, 55 Cnc, $\tau$ Boo, $\upsilon$ And, 70 Vir, 47 UMa, and Gl229, evolutionary and spectral models of gas giants and/or brown dwarfs with masses from 0.3 through 60 times that of Jupiter assume a…

天体物理学 · 物理学 2016-08-30 A. Burrows , W. B. Hubbard , J. I. Lunine , M. Marley T. Guillot , D. Saumon , R. S. Freedman

We present a rotational velocity (vsini) survey of 32 stellar/substellar objects and giant planets using Keck/KPIC high-resolution spectroscopy, including 6 giant planets (2-7 M$_\mathrm{Jup}$) and 25 substellar/stellar companions (12-88…

We examine the evolution of low-mass star and brown dwarf eclipsing binaries. These objects are rapid rotators and are believed to shelter large magnetic fields. We suggest that reduced convective efficiency, due to fast rotation and large…

天体物理学 · 物理学 2008-12-18 Gilles Chabrier , Jose Gallardo , Isabelle Baraffe

The formation of gas giant planets must occur during the first few Myr of a star's lifetime, when the protoplanetary disc still contains sufficient gas to be accreted onto the planetary core. The majority of protoplanetary discs are exposed…

地球与行星天体物理 · 物理学 2022-06-08 Andrew J. Winter , Thomas J. Haworth , Gavin A. L. Coleman , Sergei Nayakshin

We present evolutionary models for cool brown dwarfs and extra-solar giant planets. The models reproduce the main trends of observed methane dwarfs in near-IR color-magnitude diagrams. We also present evolutionary models for irradiated…

天体物理学 · 物理学 2009-07-09 I. Baraffe , G. Chabrier , T. Barman , F. Allard , P. H. Hauschildt

Magnetic fields can play an important role in stellar evolution. Among white dwarfs, the most common stellar remnant, the fraction of magnetic systems is more than 20 per cent. The origin of magnetic fields in white dwarfs, which show…

太阳与恒星天体物理 · 物理学 2022-04-27 Ingrid Pelisoli , M. Dorsch , U. Heber , B. Gänsicke , S. Geier , T. Kupfer , P. Németh , S. Scaringi , V. Schaffenroth

A small percentage of normal stars harbor giant planets that orbit within a few tenths of an astronomical unit. At such distances the potential exists for significant tidal and magnetic field interaction resulting in energy dissipation that…

太阳与恒星天体物理 · 物理学 2015-05-19 Caleb A. Scharf

A significant fraction of white dwarfs harbour a magnetic field with strengths ranging from a few kG up to about 1000 MG. The fraction appears to depend on the specific class of white dwarfs being investigated and may hold some clues to the…

太阳与恒星天体物理 · 物理学 2018-01-18 A. Kawka

We present scaling laws for advection, radiation, magnetic drag and ohmic dissipation in the atmospheres of hot giant exoplanets. In the limit of weak thermal ionization, ohmic dissipation increases with the planetary equilibrium…

地球与行星天体物理 · 物理学 2015-05-30 Kristen Menou

Chemically peculiar Ap and Bp stars host strong large-scale magnetic fields in the range of $200$~G up to $30$~kG, which are often considered to be the origin of fossil magnetic fields. We assess the evolution of such fossil fields during…

太阳与恒星天体物理 · 物理学 2023-06-30 Dominik R. G. Schleicher , Juan Pablo Hidalgo , Daniele Galli

We have detected longitudinal magnetic fields between 2 and 4 kG in three (WD 0446$-$790, WD 1105$-$048, WD 2359$-$434) out of a sample of 12 normal DA white dwarfs by using optical spectropolarimetry done with the VLT Antu 8 m telescope…

天体物理学 · 物理学 2016-08-16 R. Aznar Cuadrado , S. Jordan , R. Napiwotzki , H. M. Schmid , S. K. Solanki , G. Mathys

We have detected longitudinal magnetic fields between 2 and 4kG in three normal DA white dwarfs (WD0446-790, WD1105-048, WD2359$-$434) out of a sample of 12 by using optical spectropolarimetry done with the VLT Antu 8 m telescope equipped…

天体物理学 · 物理学 2007-05-23 R. Aznar Cuadrado , S. Jordan , R. Napiwotzki , H. M. Schmid , S. K. Solanki , G. Mathys

We review the current state of our knowledge concerning the rotation and angular momentum evolution of young stellar objects and brown dwarfs from a primarily observational view point. Periods are typically accurate to 1% and available for…

天体物理学 · 物理学 2007-05-23 W. Herbst , J. Eisloeffel , R. Mundt , A. Scholz

We study the cosmic evolution of the magnetic fields of a large sample of spiral galaxies in a cosmologically representative volume by employing a semi-analytic galaxy formation model and numerical dynamo solver in tandem. We start by…

星系天体物理 · 物理学 2019-01-03 Luiz Felippe S. Rodrigues , Luke Chamandy , Anvar Shukurov , Carlton M. Baugh , A. Russ Taylor

Existing upper limits on variations in the photospheric radius of the Sun during the solar magnetic activity cycle are at a fractional amplitude of 2x10^{-4}. At that level, the transit duration of a close-in planet around a Sun-like star…

天体物理学 · 物理学 2009-11-13 Abraham Loeb

Observations and models suggest that the conditions to develop lightning may be present in cloud-forming extrasolar planetary and brown dwarf atmospheres. Whether lightning on these objects is similar to or very different from what is known…

地球与行星天体物理 · 物理学 2021-06-15 G. Hodosán , Ch. Helling , I. Vorgul

We study the magnetic and tidal interactions of a gas-giant exoplanet with its host star and with its exomoons, and focus on their retention. We briefly revisit the scaling law for planetary dynamo in terms of its mass, radius and…

地球与行星天体物理 · 物理学 2024-03-12 Xing Wei , D. N. C. Lin

New results based on methods of population synthesis, concerning magnetic field effects on the evolution of pulsars are reported. The present study confirms that models with timescales for the magnetic field decay longer than the pulsar…

天体物理学 · 物理学 2009-11-06 T. Regimbau , J. A. de Freitas Pacheco

The evolutions of a neutron star's rotation and magnetic field (B-field) have remained unsolved puzzles for over half a century. We ascribe the rotational braking torques of pulsar to both components, the standard magnetic dipole radiation…

The magnetic white dwarfs (MWDs) are found either isolated or in interacting binaries. They divide into two groups: a high field group (0.1-1,000MegaGauss) comprising some 13% of all white dwarfs (WDs), and a low field group (B<0.1MG) whose…

太阳与恒星天体物理 · 物理学 2020-01-29 Lilia Ferrario , D. T. Wickramasinghe , Adela Kawka