Cracking the Conundrum of F-Supergiant Coronae

@article{Ayres2016CrackingTC,
  title={Cracking the Conundrum of F-Supergiant Coronae},
  author={T. Ayres},
  journal={arXiv: Solar and Stellar Astrophysics},
  year={2016}
}
  • T. Ayres
  • Published 2016
  • Physics, Materials Science
  • arXiv: Solar and Stellar Astrophysics
Chandra X-ray and HST far-ultraviolet (FUV) observations of three early-F supergiants have shed new light on a previous puzzle involving a prominent member of the class: Alpha Persei (HD20902: F5Ib). The warm supergiant is a moderately strong, hard coronal (T~10MK) X-ray source, but has ten times weaker "sub-coronal" Si IV 139 nm (T~80,000 K) emissions than early-G supergiants of similar high-energy properties. The Alpha Per X-ray excess speculatively was ascribed to a close-in hyperactive G… Expand

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References

SHOWING 1-10 OF 19 REFERENCES
THE CURIOUS CASE OF THE ALPHA PERSEI CORONA: A DWARF IN SUPERGIANT'S CLOTHING?
Alpha Persei (HD 20902: F5 Iab) is a luminous, nonvariable supergiant located at the blue edge of the Cepheid instability strip. It is one of the brightest coronal X-ray sources in the young openExpand
A Closer Look at the Alpha Persei Coronal Conundrum
A ROSAT survey of the Alpha Per open cluster in 1993 detected its brightest star, mid-F supergiant Alpha Persei: the X-ray luminosity and spectral hardness were similar to coronally active late-typeExpand
Chandra Observations of Coronal Emission from the Early G Supergiants α and β Aquarii
We report Chandra detections of coronal X-rays from the early G supergiants α Aquarii (HD 209750: G2 Ib) and β Aquarii (HD 204867: G0 Ib). Previous ROSAT observations of these archetypical "hybridExpand
The Flare-ona of EK Draconis
EK Draconis (HD 129333: G1.5 V) is a well-known young (50 Myr) solar analog. In 2012, Hubble Space Telescope returned to EK Dra to follow up a far-ultraviolet (FUV) SNAPshot visit by Cosmic OriginsExpand
BURIED ALIVE IN THE CORONAL GRAVEYARD
We have used the High Resolution Camera (HRC-I) of the Chandra X-Ray Observatory to search for coronal (T � 10 6 K) emission from the archetype ‘‘ noncoronal ’’ red giants Arcturus (� Bootis=HDExpand
The Secret Lives of Cepheids: δ Cep - The Prototype of a New Class of Pulsating X-Ray Variable Stars∗
From our Secret Lives of Cepheids program, the prototype Classical Cepheid, $\delta$ Cep, is found to be an X-ray source with periodic pulsation-modulated X-ray variations. This finding complementsExpand
An analysis of the shapes of interstellar extinction curves. V. The IR-through-UV curve morphology
We study the IR-through-UV wavelength dependence of 328 Galactic interstellar extinction curves affecting normal, near-main-sequence B and late O stars. We derive the curves using a new techniqueExpand
The secret lives of Cepheids: evolutionary changes and pulsation-induced shock heating in the prototype classical Cepheid δ Cep
Over the past decade, the Secret Lives of Cepheids (SLiC) program has been carried out at Villanova University to study aspects and behaviors of classical Cepheids that are still not well understood.Expand
An atlas of ultraviolet P Cygni profiles
We have selected spectra of 232 stars from the International Ultraviolet Explorer (IUE) archives for inclusion in an atlas intended for various uses but tailored especially for the study of stellarExpand
Precision Kinematics and Related Parameters of the α Persei Open Cluster
A kinematical study of the nearby open cluster α Persei is presented based on the astrometric proper motions and positions in the Tycho-2 catalog and Second USNO CCD Astrographic Catalog (UCAC2).Expand
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