X-ray astronomy of stellar coronae

By M. Gudel. 2004

274 citations recorded by the source corpus.

Abstract.X-ray emission from stars in the cool half of the Hertzsprung-Russell diagram is generally attributed to the presence of a magnetic corona that contains plasma at temperatures exceeding 1 million K. Coronae are ubiquitous among these stars, yet many fundamental mechanisms operating in their magnetic fields still elude an interpretation through a detailed physical description. Stellar X-ray astronomy is therefore contributing toward a deeper understanding of the generation of magnetic fields in magnetohydrodynamic dynamos, the release of energy in tenuous astrophysical plasmas through various plasma-physical processes, and the interactions of high-energy radiation with the stellar environment. Stellar X-ray emission also provides important diagnostics to study the structure and evolution of stellar magnetic fields from the first days of a protostellar life to the latest stages of stellar evolution among giants and supergiants. The discipline of stellar coronal X-ray astronomy has now reached a level of sophistication that makes tests of advanced theories in stellar physics possible. This development is based on the rapidly advancing instrumental possibilities that today allow us to obtain images with sub-arcsecond resolution and spectra with resolving powers exceeding 1000. High-resolution X-ray spectroscopy has, in fact, opened new windows into astrophysical sources, and has played a fundamental role in coronal research.The present article reviews the development and current status of various topics in the X-ray astronomy of stellar coronae, focusing on observational results and on theoretical aspects relevant to our understanding of coronal magnetic structure and evolution.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/e1b9974dc65ad61d43e639a273792fd63b39da63

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In Astronomy and Astrophysics

1. Bing Zhang
2. J. Owen
3. Pawan Kumar
4. C. Mordasini
5. Sheng Jin
6. A. Pe’er
7. F. Ryde
8. L. Amati

In Instrumentation

1. Bing Zhang
2. J. Owen
3. Sheng Jin
4. C. Mordasini
5. L. Amati
6. G. Ghisellini
7. Barbara Ercolano
8. R. van Boekel

Citations in the corpus

• Protoplanetary disc evolution and dispersal: the implications of X-ray photoevaporation (2010, background): “…known that the median of the stellar X-ray luminosity function does in fact decrease with age due to stellar spin down (e.g. Hemplemann et al. 1995; Güdel et al. 1997; Güdel 2004), the evolution of the X-ray luminosity during the disc dispersal phase is much smaller (see Figure 41, Güdel 2004).”
• The chemical composition of the Sun (2009, background): “Their sample is, however, heavily biased towards active stars, which experience an inverse FIP effect: elements with χion > 10 eV are enhanced in the corona compared with low ionization potential species (Güdel 2004).”
• KEPLER FLARES. I. ACTIVE AND INACTIVE M DWARFS (2014, background): “Güdel (2004) reviewed X-ray results and noted several studies that obtain α > 2.”
• KEPLER PLANETS: A TALE OF EVAPORATION (2013, background): “For the first ∼ 100 Myrs of their lives, main-sequence stars have X-ray luminosities that reach up to ∼ 10−3 of their bolometric luminosities; this fraction falls off with time roughly as 1/t as the stars age (Güdel 2004; Ribas et al. 2005; Jackson et al. 2012).”
• The Solar Chemical Composition (2004, background): “We suggest, with Güdel (2004), that the solar corona, in some highly magnetically active centers, might perhaps also exhibit such an inverse FIP effect.”
• X-ray luminosity function of faint point sources in the Milky Way (2005, background): “In contrast, the statistics of young coronal stars (YSs), another abundant class of low-luminosity X-ray sources (see Güdel 2004, for a review), is expected to be governed by local star formation history, so that an XLF constructed for this class of sources in the solar neighborhood may not be…”
• Stellar Activity on the Young Suns of Orion: COUP Observations of K5-7 Pre-Main-Sequence Stars (2005, background): “…show high-amplitude rapid variability and the type of hard spectra that are associated with violent magnetic reconnection flares when seen on the surface of the Sun, dMe flare stars, and other magnetically active late-type stars (Feigelson & Montmerle 1999; Favata & Micela 2003; Güdel 2004).”
• Magnetic Reconnection in Astrophysical and (2009, background): “Stellar activity is magnetically driven, and stellar flares are similar to solar flares (Rosner et al. 1985; Haisch, Strong & Rodono 1991; Güdel 2004).”
• PLANETARY POPULATION SYNTHESIS COUPLED WITH ATMOSPHERIC ESCAPE: A STATISTICAL VIEW OF EVAPORATION (2014, background): “On the other hand, the stellar X-ray emissions are highly diverse (Güdel 2004).”
• The Evolution of X-Ray Emission in Young Stars (2005, background): “…of evolution from Class I protostars through the ZAMS (Getman et al. 2005b; Preibisch et al. 2005). activity, exceeding the solar levels by several orders of magnitude both in time-averaged luminosity and power of individual flares (Feigelson & Montmerle 1999; Favata & Micela 2003; Güdel 2004).”
• The THESEUS space mission concept: science case, design and expected performances (2017, background): “X-ray flares have long been detected and cataloged (see, e.g., Pye & McHardy, 1983; Favata, 2002; Güdel, 2004), but rare “superflares” can briefly (∼1000 s) exceed the star’s quiescent bolometric luminosity, and only a handful are known (see, e.g., RS CVn binary II Peg and dMe star EV Lac; Osten…”