Main sequence stars beyond G2 that experience hot corona phenomena include F-, G-, K-, and M-type stars, which possess chromospheres and coronae similar to the Sun. FK Comae Berenices serves as a notable example, exhibiting extreme activity and luminous X-ray coronae with temperatures reaching up to 40 MK. The primary mechanism for coronal heating is linked to interactions with stellar magnetic fields, although the exact energy transfer processes remain under investigation. Upcoming missions like the Parker Solar Probe are anticipated to provide further insights into these phenomena.
PREREQUISITESAstronomers, astrophysicists, and students interested in stellar phenomena, particularly those studying stellar coronae and magnetic field interactions.
spossatamente said:We know that solar corona is heated up although we don't know yet the mechanism
spossatamente said:I was wondering which other type of stars, else than G2, in the main sequence suffer of the same effect?
regardsStellar coronae[edit]
Coronal stars are ubiquitous among the stars in the cool half of the Hertzsprung–Russell diagram.[17] These coronae can be detected using X-ray telescopes. Some stellar coronae, particularly in young stars, are much more luminous than the Sun's. For example, FK Comae Berenices is the prototype for the FK Com class of variable star. These are giants of spectral types G and K with an unusually rapid rotation and signs of extreme activity. Their X-ray coronae are among the most luminous (Lx ≥ 1032 erg·s−1 or 1025W) and the hottest known with dominant temperatures up to 40 MK.[17]
The astronomical observations planned with the Einstein Observatory by Giuseppe Vaiana and his group[18] showed that F-, G-, K- and M-stars have chromospheres and often coronae much like our Sun. The O-B stars, which do not have surface convection zones, have a strong X-ray emission. However these stars do not have coronae, but the outer stellar envelopes emit this radiation during shocks due to thermal instabilities in rapidly moving gas blobs. Also A-stars do not have convection zones but they do not emit at the UV and X-ray wavelengths. Thus they appear to have neither chromospheres nor coronae