katsova m.m. , livshits М.А. sternberg astronomical institute, moscow state university

KATSOVA M.M., LIVSHITS М.А. 

Sternberg Astronomical Institute, Moscow State UniversityIZMIRAN, Troitsk

HOW STELLAR FLARE EXPERIENCE CAN HELP IN SOLAR INVESTIGATIONS?

Our SUN

The soft X-ray emission of the late-type stars

- ROSAT, 0.1 – 2.4 keV

- The Sunat the same spectal range, max, min

- Stars from J.Wright et al, 2004

- Stars of HK Project S.Baliunas et al.

The soft X-ray emission of the late-type stars

The chromospheric radiation of the late-type stars

Spots on active late-type stars

• Thus, the Sun enters naturally in a family of cyclic stars:

the Sun among the active stars with cycles is a hotter star, rotating comparatively faster, while solar spots cover relatively less area than spots on active stars.

Some features : cycles

1992 1998

• Evidence for coronal activity cycles on 61 Cyg A and B

• A.Hempelman, J.H.M.M.Schmitt, S.L.Baliunas and R.A.Donahue

A & A (2003) V.406, L.39

61 Cyg A

Ca II

X-Ray

ROSATHRI

Some features: cycles and long-term variability of the Sun and some stars

1975 2000 1965 2000

X-rays

Ca II

Solar irradiance

HD 1835 Optical continuumV

Ca II

HD 10476

V

Ca II

STELLAR CORONAE: spectra, XMM-Newton

M.Güdel, “X-ray astronomy of stellar coronae”. Astron. Astrophys. Rev. 2004

STELLAR CORONAE : ЕМ, Т

6.0 7.0 log T

7.0

6.0

log L(x) 27 29 31

52

50

48

46 M.Güdel. “X-ray astronomy of stellar coronae”.

Astron. Astrophys. Rev. 2004

log EM log T

IMPULSIVE STELLAR FLARES

GAS-DYNAMIC MODELLING:

Livshits, Badalyan, Kosovichev and Katsova, 1981, Solar Phys. 73, 269

Katsova, Boiko, Livshits, 1997A & A , 321, 549

IMPULSIVE FLARES: results and experience

Interpretation of simultaneous observations at various spectral ranges

Estimation of amount of the evaporated plasma

The most reliable method of estimation of the stellar flare area in optics

Analysis of secondary processes allows us to conclude about properties of primary energy release

Flares on red dwarf stars

M. Guedel

“X-ray astronomy

of stellar coronae”

Astron. Astrophys. Rev.

2004

Flares on red dwarf stars

Prox Cen

EQ Peg

Flare duration in optics – 5 minThe EM of flare coronal loops is much

more than it was expected from the optical data

Katsova, Livshits, J.H.M.M.Schmitt 2002, 2005 “Short powerful flare on EQ Peg as an analog of solar compact flares”

UX Ari

I.M.Livshits, M.A.Livshits, R.Pallavicini, 2003, Adv.Space Res. 32(6), 1181

CORONAL HEATING

Red dwarf stars -microflaring

G-K stars with cycles –

plasma heating in coronal loops

Active F-G dwarfs and subgiants – prolonged non-stationary

processes in corona

The Sun among active late-type stars with cycles is a typical one.The soft X-ray emission of stellar coronae allows us to analyse processes in different physical conditions and to distinguish phenomena developing both in strong local and large-scale magnetic fields. It helps to understand how can change the solar corona if heating increases by 3-4 orders of a magnitude and will be realized at small and large spatial structures.If solar non-stationary phenomena are characterized by energies up to 1032 ergs, so stellar flares give possibility to investigate much more powerful events with total energies up to 1036 ergs. Therefore there is a chance to observe phenomena associated either with a pulse only or with prolonged primary energy release

HOW STELLAR FLARE EXPERIENCE CAN HELP IN SOLAR INVESTIGATIONS? CONCLUSIONS

The End