Altair – the “hottest” magnetically active star in X-rays

@article{Robrade2009AltairT,
  title={Altair – the “hottest” magnetically active star in X-rays},
  author={J. Robrade and J{\"u}rgen H. M. M. Schmitt},
  journal={Astronomy and Astrophysics},
  year={2009},
  volume={497},
  pages={511-520}
}
Context. The onset of stellar magnetic activity is related to the operation of dynamo processes that require the development of an outer convective layer. This transition of stellar interior structure is expected to occur in late A-type stars. Aims. The A7 star Altair is one of the hottest magnetically active stars. Its proximity to the Sun allows a detailed investigation of a corona in X-rays for a star with a shallow convection zone. Methods. We used a deep XMM-Newton observation of Altair… 

Figures and Tables from this paper

BURN OUT OR FADE AWAY? ON THE X-RAY AND MAGNETIC DEATH OF INTERMEDIATE MASS STARS
The nature of the mechanisms apparently driving X-rays from intermediate mass stars lacking strong convection zones or massive winds remains poorly understood, and the possible role of hidden, lower
Intriguing X-ray and optical variations of the γ Cassiopeiae analog HD 45314
Context. A growing number of Be and Oe stars, named the γ Cas stars, are known for their unusually hard and intense X-ray emission. This emission could either trace accretion by a compact companion
Search of X-ray emission from roAp stars: the case of γ Equulei
The detection of X-ray emission from Ap stars can be an indicator for the presence of magnetic activity and dynamo action, provided different origins for the emission, such as wind shocks and close
X-ray emission from the remarkable A-type star HR 8799
We present a Chandra observation of the exceptional planet bearing A5V star HR 8799, more precisely classified as a kA5hF0mA5 star and search for intrinsic X-ray emission. We clearly detect HR 8799
New X-ray observations of IQ Aurigae and α2 Canum Venaticorum - Probing the magnetically channeled wind shock model in A0p stars
We present new X-ray observations of the A0p stars alpha^2 CVn (log Lx < 26.0 erg/s) and IQ Aur (log Lx = 29.6 erg/s) and find that their X-ray luminosities differ by at least three orders of
LOCATING THE ACCRETION FOOTPRINT ON A HERBIG Ae STAR: MWC 480
Accretion is a fundamental process which establishes the dynamics of the protoplanetary disk and the final properties of the forming star. In solar-type stars, the star–disk coupling is determined by
The Relative Emission from Chromospheres and Coronae: Dependence on Spectral Type and Age
Extreme-ultraviolet and X-ray emission from stellar coronae drives mass loss from exoplanet atmospheres, and ultraviolet emission from stellar chromospheres drives photochemistry in exoplanet
A Chandra/LETGS Survey of Main-sequence Stars
We analyze the X-ray spectra of 19 main-sequence stars observed by Chandra using its LETGS configuration. Emission measure (EM) distributions are computed based on emission line measurements, an
Chromospheric emission of solar-type stars with asteroseismic ages
Stellar magnetic activity decays over the main-sequence life of cool stars due to the stellar spin-down driven by magnetic braking. The evolution of chromospheric emission is well studied for
...
...

References

SHOWING 1-10 OF 35 REFERENCES
An Einstein Observatory X-ray survey of main-sequence stars with shallow convection zones
The results of an X-ray survey of bright late A and early F stars on the main B-V sequence between 0.1 and 0.5 are presented. All the stars were observed with the Einstein Observatory for a period of
High Chromospheres of Late A Stars
We report the detection of N V 1239 Å transition region emission in HST/Goddard High Resolution Spectrograph spectra of the A7 V stars, α Aql and α Cep. Our observations provide the first direct
Doppler imaging an X-ray flare on the ultrafast rotator BO Mic - A contemporaneous multiwavelength
We present an analysis of contemporaneous photospheric, chromospheric and coronal structures on the highly active K-dwarf star BO Mic (Speedy Mic). We concentrate on a moderate flare that we localize
X-ray emission from A-type stars
Being fully radiative, stars of spectral type A are not expected to harbor magnetic dynamos and hence such stars are not expected to produce X-ray emission. Indeed, while the X-ray detection rate of
Chromospheric models for Altair (A7 IV-V)
The star, Altair (A7 IV-V), is clearly shown to have Lyman-alpha emission of chromospheric origin, while no evidence is found for the Mg II emission reported in previous investigations. We present
Rotation, convection, and magnetic activity in lower main-sequence stars
Rotation periods are reported for 14 main-sequence stars, bringing the total number of such stars with well-determined rotation periods to 41. It is found that the mean level of their Ca n H and K
Einstein Observations of X-ray emission from A stars
Results are reported from the combined CfA Stellar Survey of selected bright A stars and an Einstein Guest Observer program for Ap and Am stars. In an initial report of results from the CfA Stellar
The stellar activity-rotation relationship revisited: Dependence of saturated and non-saturated X-ray emission regimes on stellar mass for late-type dwarfs ?
We present the results of a new study on the relationship between coronal X-ray emission and stellar rotation in late-type main-sequence stars. We have selected a sample of 259 dwarfs in the B V
Coronal activity-rotation relations for lower main-sequence stars
The relationship between stellar soft X-ray emission and rotation has been examined using a sample of 157 lower main-sequence stars from various clusters and the field. The highest correlation
On the sizes of stellar X-ray coronae
Spatial information from stellar X-ray coronae cannot be assessed directly, but scaling laws from the solar corona make it possible to estimate sizes of stellar coronae from the physical parameters
...
...