The structure of coronal plasma in active stellar coronae from density measurements

Giovanni Peres, Drake, Paola Testa, Paola Testa

Risultato della ricerca: Other

Abstract

We have analyzed high-resolution X-ray spectra of a sample of 22 active stars observed with the High Energy Transmission Grating Spectrometer (HETGS) on Chandra in order to investigate their coronal plasma density, using the lines of the He-like ions O VII, Mg XI, and Si XIII. Si XII lines in all stars of the sample axe compatible with the low-density limit (i.e. n(e) < 10(13) cm(-3)); Mg XI lines reveal the presence of high plasma densities up to a few 10(12) cm(-3) for most of the sources with higher X-ray luminosity (>= 10(30) erg/s); O VII lines yield much lower densities of a few 10(10) cm(-3). Our results indicate that the "hot" and "cool" plasma resides in physically different structures.Our findings imply remarkably compact coronal structures, especially for the hotter (similar to 7 MK) plasma emitting the Mg xi lines characterized by coronal surface filling factor, f(MgXI), ranging from 10(-4) to 10(-1), while we find f(OVII) values from a few 10(-3) up to similar to 1 for the cooler (similar to 2 MK) plasma emitting the O VII lines.
Lingua originaleEnglish
Numero di pagine4
Stato di pubblicazionePublished - 2005

Fingerprint

stellar coronas
corona
Plasmas
plasma
Stars
stars
Plasma density
Diffraction gratings
coolers
plasma density
Spectrometers
gratings
spectrometers
erg
X rays
spectrometer
high resolution
Ions
ion
ions

All Science Journal Classification (ASJC) codes

  • Aerospace Engineering
  • Space and Planetary Science

Cita questo

The structure of coronal plasma in active stellar coronae from density measurements. / Peres, Giovanni; Drake; Testa, Paola; Testa, Paola.

2005.

Risultato della ricerca: Other

@conference{32d61063143b47e8b9fe044b9ee9f236,
title = "The structure of coronal plasma in active stellar coronae from density measurements",
abstract = "We have analyzed high-resolution X-ray spectra of a sample of 22 active stars observed with the High Energy Transmission Grating Spectrometer (HETGS) on Chandra in order to investigate their coronal plasma density, using the lines of the He-like ions O VII, Mg XI, and Si XIII. Si XII lines in all stars of the sample axe compatible with the low-density limit (i.e. n(e) < 10(13) cm(-3)); Mg XI lines reveal the presence of high plasma densities up to a few 10(12) cm(-3) for most of the sources with higher X-ray luminosity (>= 10(30) erg/s); O VII lines yield much lower densities of a few 10(10) cm(-3). Our results indicate that the {"}hot{"} and {"}cool{"} plasma resides in physically different structures.Our findings imply remarkably compact coronal structures, especially for the hotter (similar to 7 MK) plasma emitting the Mg xi lines characterized by coronal surface filling factor, f(MgXI), ranging from 10(-4) to 10(-1), while we find f(OVII) values from a few 10(-3) up to similar to 1 for the cooler (similar to 2 MK) plasma emitting the O VII lines.",
author = "Giovanni Peres and Drake and Paola Testa and Paola Testa",
year = "2005",
language = "English",

}

TY - CONF

T1 - The structure of coronal plasma in active stellar coronae from density measurements

AU - Peres, Giovanni

AU - Drake, null

AU - Testa, Paola

AU - Testa, Paola

PY - 2005

Y1 - 2005

N2 - We have analyzed high-resolution X-ray spectra of a sample of 22 active stars observed with the High Energy Transmission Grating Spectrometer (HETGS) on Chandra in order to investigate their coronal plasma density, using the lines of the He-like ions O VII, Mg XI, and Si XIII. Si XII lines in all stars of the sample axe compatible with the low-density limit (i.e. n(e) < 10(13) cm(-3)); Mg XI lines reveal the presence of high plasma densities up to a few 10(12) cm(-3) for most of the sources with higher X-ray luminosity (>= 10(30) erg/s); O VII lines yield much lower densities of a few 10(10) cm(-3). Our results indicate that the "hot" and "cool" plasma resides in physically different structures.Our findings imply remarkably compact coronal structures, especially for the hotter (similar to 7 MK) plasma emitting the Mg xi lines characterized by coronal surface filling factor, f(MgXI), ranging from 10(-4) to 10(-1), while we find f(OVII) values from a few 10(-3) up to similar to 1 for the cooler (similar to 2 MK) plasma emitting the O VII lines.

AB - We have analyzed high-resolution X-ray spectra of a sample of 22 active stars observed with the High Energy Transmission Grating Spectrometer (HETGS) on Chandra in order to investigate their coronal plasma density, using the lines of the He-like ions O VII, Mg XI, and Si XIII. Si XII lines in all stars of the sample axe compatible with the low-density limit (i.e. n(e) < 10(13) cm(-3)); Mg XI lines reveal the presence of high plasma densities up to a few 10(12) cm(-3) for most of the sources with higher X-ray luminosity (>= 10(30) erg/s); O VII lines yield much lower densities of a few 10(10) cm(-3). Our results indicate that the "hot" and "cool" plasma resides in physically different structures.Our findings imply remarkably compact coronal structures, especially for the hotter (similar to 7 MK) plasma emitting the Mg xi lines characterized by coronal surface filling factor, f(MgXI), ranging from 10(-4) to 10(-1), while we find f(OVII) values from a few 10(-3) up to similar to 1 for the cooler (similar to 2 MK) plasma emitting the O VII lines.

UR - http://hdl.handle.net/10447/231962

M3 - Other

ER -