The Selection of Ground Stations for Igs Products

Jung, Sungwook; Baek, Ji-Hye; Bae, Tae-Suk; Jo, Jung Hyun; Cho, Sung-Ki; Park, Jong‐Uk

doi:10.5140/jass.2007.24.4.417

Cited by 3 publications

(7 citation statements)

References 2 publications

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“…Preibisch et al 2005;Telleschi et al 2007), which allows for a more direct comparison with our results; differences then being attributable to the updated spectral typing and our use of PMS calibrated intrinsic colours and bolometric corrections. In Appendix D we demonstrate, using the models of Jung & Kim (2007) and Tognelli, Prada Moroni & Degl'Innocenti (2011), that the main results of our paper, described in the following sections, are unaffected by the choice of PMS evolutionary model.…”

Section: Stellar Parameters: Mass Age and Internal Structurementioning

confidence: 81%

“…In this Appendix we demonstrate that our results are independent of the adopted PMS mass tracks and isochrones. Starting with our final sample of 984 PMS stars (including the 34 L X upper limits), see section 3, we recalculated the stellar masses, ages, and radiative core masses, using the PMS evolutionary models of Jung & Kim (2007). Co-author Y.-C. Kim kindly supplied us with more detailed grids than published as well as stellar internal structure information.…”

Section: Appendix D: a Comparison Of The Correlations Using Differentmentioning

confidence: 99%

“…Co-author Y.-C. Kim kindly supplied us with more detailed grids than published as well as stellar internal structure information. All 984 stars fell within the grid of Jung & Kim (2007). We Figure C2.…”

Section: Appendix D: a Comparison Of The Correlations Using Differentmentioning

confidence: 99%

“…The correlation between L X and age, t, does initially appear to be model dependent. For example, in the highest mass bin, 2-3 M , there is no correlation when using the Jung & Kim (2007) or Tognelli et al (2011) models. There are only 15 and 16 stars in this mass range in the two models, respectively, compared to 24 stars when using the Siess et al (2000) models.…”

Section: Appendix D: a Comparison Of The Correlations Using Differentmentioning

confidence: 99%

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The influence of radiative core growth on coronal X-ray emission from pre-main-sequence stars

Gregory¹,

Adams²,

Davies³

2016

Mon. Not. R. Astron. Soc.

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Pre-main sequence (PMS) stars of mass 0.35 M transition from hosting fully convective interiors to configurations with a radiative core and outer convective envelope during their gravitational contraction. This stellar structure change influences the external magnetic field topology and, as we demonstrate herein, affects the coronal X-ray emission as a stellar analog of the solar tachocline develops. We have combined archival X-ray, spectroscopic, and photometric data for ∼1000 PMS stars from five of the best studied star forming regions; the ONC, NGC 2264, IC 348, NGC 2362, and NGC 6530. Using a modern, PMS calibrated, spectral type-to-effective temperature and intrinsic colour scale, we deredden the photometry using colours appropriate for each spectral type, and determine the stellar mass, age, and internal structure consistently for the entire sample. We find that PMS stars on Henyey tracks have, on average, lower fractional X-ray luminosities (L X /L * ) than those on Hayashi tracks, where this effect is driven by changes in L X . X-ray emission decays faster with age for higher mass PMS stars. There is a strong correlation between L * and L X for Hayashi track stars but no correlation for Henyey track stars. There is no correlation between L X and radiative core mass or radius. However, the longer stars have spent with radiative cores, the less X-ray luminous they become. The decay of coronal X-ray emission from young early K to late G-type PMS stars, the progenitors of main sequence A-type stars, is consistent with the dearth of X-ray detections of the latter.

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Section: Stellar Parameters: Mass Age and Internal Structurementioning

confidence: 81%

Section: Appendix D: a Comparison Of The Correlations Using Differentmentioning

confidence: 99%

Section: Appendix D: a Comparison Of The Correlations Using Differentmentioning

confidence: 99%

Section: Appendix D: a Comparison Of The Correlations Using Differentmentioning

confidence: 99%

See 2 more Smart Citations

The influence of radiative core growth on coronal X-ray emission from pre-main-sequence stars

Gregory¹,

Adams²,

Davies³

2016

Mon. Not. R. Astron. Soc.

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“…Unfortunately most published τ c estimates come from models that track the stellar evolution over timescales of order Gyr and across a limited range of stellar mass (Gilliland 1986;Kim & Demarque 1996;Landin et al 2010), and lack the time and mass resolution required for our purposes. An exception is the model of Jung & Kim (2007). Y.-C. Kim has kindly supplied us with finer resolution grids than published.…”

Section: Magnetic Field Topology Rotation Rate and Rossby Numbermentioning

confidence: 99%

Can We Predict the Global Magnetic Topology of a Pre-Main-Sequence Star From Its Position in the Hertzsprung–russell Diagram?

Gregory

Donati

Morin

et al. 2012

ApJ

173

219

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Zeeman-Doppler imaging studies have shown that the magnetic fields of T Tauri stars can be significantly more complex than a simple dipole and can vary markedly between sources. We collect and summarize the magnetic field topology information obtained to date and present Hertzsprung-Russell (HR) diagrams for the stars in the sample. Intriguingly, the large scale field topology of a given pre-main sequence (PMS) star is strongly dependent upon the stellar internal structure, with the strength of the dipole component of its multipolar magnetic field decaying rapidly with the development of a radiative core. Using the observational data as a basis, we argue that the general characteristics of the global magnetic field of a PMS star can be determined from its position in the HR diagram. Moving from hotter and more luminous to cooler and less luminous stars across the PMS of the HR diagram, we present evidence for four distinct magnetic topology regimes. Stars with large radiative cores, empirically estimated to be those with a core mass in excess of ∼40% of the stellar mass, host highly complex and dominantly non-axisymmetric magnetic fields, while those with smaller radiative cores host axisymmetric fields with field modes of higher order than the dipole dominant (typically, but not always, the octupole). Fully convective stars stars above 0.5 M appear to host dominantly axisymmetric fields with strong (kilo-Gauss) dipole components. Based on similarities between the magnetic properties of PMS stars and main sequence M-dwarfs with similar internal structures, we speculate that a bistable dynamo process operates for lower mass stars ( 0.5 M at an age of a few Myr) and that they will be found to host a variety of magnetic field topologies. If the magnetic topology trends across the HR diagram are confirmed they may provide a new method of constraining PMS stellar evolution models.

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The Bifurcation Periods in Low-Mass X-Ray Binaries: The Effect of Magnetic Braking and Mass Loss

2009

ApJ

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The bifurcation period in low-mass X-ray binaries is the initial orbital period which separates the formation of converging systems (which evolve with decreasing orbital periods until the donor becomes degenerate) from the diverging systems (which evolve with increasing orbital periods until the donor star loses its envelope and a wide detached binary is formed). We calculate systematically the bifurcation periods of binary systems with a 1.4M ⊙ neutron star and a 0.5 − 2M ⊙ donor star, taking into account different kinds of magnetic braking and mass loss mechanisms. Our results show that the saturated magnetic braking can considerably decrease the values of bifurcation period compared to the traditional magnetic braking, while the influence of mass loss mechanisms on bifurcation periods is quite weak. We also develop a semi-analytical method to compute the bifurcation period, the result of which agrees well with the numerical method in the leading order.

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The Selection of Ground Stations for Igs Products

Cited by 3 publications

References 2 publications

The influence of radiative core growth on coronal X-ray emission from pre-main-sequence stars

The influence of radiative core growth on coronal X-ray emission from pre-main-sequence stars

Can We Predict the Global Magnetic Topology of a Pre-Main-Sequence Star From Its Position in the Hertzsprung–russell Diagram?

The Bifurcation Periods in Low-Mass X-Ray Binaries: The Effect of Magnetic Braking and Mass Loss

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