A possible mechanism of solar flare

Self Cite

Abstract. Explosive evolution of nuclei of sungrazing comets near the solar surface, which occurs at conditions of intense interaction between the solar atmosphere and falling high-velocity comet nuclei as well as the relation of the phenomenon to the character of solar activity are analytically considered. It is found that, due to aerodynamic fragmentation of the falling body in the solar chromosphere and transversal expansion of the fragmented mass under the action of pressure gradient on the frontal surface, thermalization of the kinetic energy of the body occurs by sharp stopping of the disklike hypervelocity fragmented mass near the solar surface within a relatively very thin subphotospheric layer and has, therefore, an essentially impulsive and strongly explosive character. The specific energy release in the explosion region, erg/g, considerably exceeds the evaporation/sublimation heat of the body so that the process is accompanied by production of a high-temperature plasma. The energetics of such an explosive process corresponds to that of very large solar flares for falling bodies having masses equal to the mass of the nucleus of Comet Halley. Spectral observations of sungrazing comets by SOHO-like telescopes in a wide spectral range, including X rays, with a high time resolution, of the order of 0.1-10 s, are important for revealing solar activity in the form of an impact-generated photospheric flare.

Section: Disintegration Of Comets In the Solar Atmospherementioning

confidence: 99%

Section: Disintegration Of Comets In the Solar Atmospherementioning

confidence: 99%

Explosion of sungrazing comets in the solar atmosphere and solar flares

Ibadov¹,

Ibodov²,

Grigorian³

2008

Self Cite

“…The characteristic time for thermalization of the FEB's kinetic energy within the "exploding" layer is ∼0.3 sec, at a layer thickness of roughly 0.7H = 140 km (where H is height scale of photosphere). FEBs similar to comet Halley 1986 III would release explosive energy close to the energies of large solar flares, 10 32 erg, while FEBs similar to comet Hale-Bopp 1995 OI (radius 30 km) should lead to stellar super-flares (Grigorian et al 2000;Ibadov et al 2009;Eichler & Mordecai 2012). Using similar arguments, we have explained the heights of plumes observed with HST during the collision of comet SL-9 with Jupiter in July 1994 and have predicted the ejection of plumes from young stars due to FEBs (Ibodov & Ibadov 2014 and references therein).…”

Section: Explosions Of Febs In Stellar and Planetary Atmospheresmentioning

confidence: 99%

Young Stars and Planets Near the Sun: Explosive Phenomena from Falling Evaporating Bodies

Ibadov

Ibodov

2015

Abstract. Impacts of falling evaporating bodies (FEBs) with stars and planets at velocities V 10 − 20 km/s will be accompanied, due to aerodynamic effects such as crushing and transversal expansion of the crushed mass, by the FEB's "explosion" and the generation of a strong "blast" wave, resulting in FEB-generated explosive/flare phenomena. Multiwavelength monitoring of nearby young stars (and exoplanets) with dense protoplanetary disks rich in FEB's is hence of interest for identifying such FEB-related mechanisms possibly underlying their variability.

“…Using (2.1) with ρ n = 0.5 g/cm 3 , R n = 10 5 cm, V * = V 0 , A = 20, z = 5, x 1 = 3 we have Δh e = 140 km, E e = 7 · 10 29 erg, T 0 = 7 · 10 6 K. Hence, "superflares" may be due to impacts with comets like comet Hale-Bopp 1995 OI (cf. Ibadov et al 1999;Grigoryan et al 2000;Ibadov et al 2009;Eichler & Mordecai 2012;Ibodov & Ibadov 2014).…”

Section: Massive Stars Comet-induced Flaresmentioning

confidence: 99%

Massive stars: flare activity due to infalls of comet-like bodies

Ibadov

Ibodov

2014

Abstract. Passages of comet-like bodies through the atmosphere/chromosphere of massive stars at velocities more than 600 km/s will be accompanied, due to aerodynamic effects as crushing and flattening, by impulse generation of hot plasma within a relatively very thin layer near the stellar surface/photosphere as well as "blast" shock wave, i.e., impact-generated photospheric stellar/solar flares. Observational manifestations of such high-temperature phenomena will be eruption of the explosive layer's hot plasma, on materials of the star and "exploding" comet nuclei, into the circumstellar environment and variable anomalies in chemical abundances of metal atoms/ions like Fe, Si etc. Interferometric and spectroscopic observations/monitoring of young massive stars with dense protoplanetary discs are of interest for massive stars physics/evolution, including identification of mechanisms for massive stars variability.