Non-equilibrium ionization by a periodic electron beam II. Synthetic Si IV and O IV transition region spectra

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F67985815%3A_____%2F18%3A00494687" target="_blank" >RIV/67985815:_____/18:00494687 - isvavai.cz</a>

Výsledek na webu

<a href="http://dx.doi.org/10.1051/0004-6361/201731744" target="_blank" >http://dx.doi.org/10.1051/0004-6361/201731744</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1051/0004-6361/201731744" target="_blank" >10.1051/0004-6361/201731744</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Non-equilibrium ionization by a periodic electron beam II. Synthetic Si IV and O IV transition region spectra

Popis výsledku v původním jazyce

To investigate the combination of non-equilibrium ionization and high-energy particles, we apply the model of the periodic electron beam, represented by a kappa-distribution that recurs at periods of several seconds, to plasma at chromospheric temperatures of 10(4) K. This simple model can approximate a burst of energy release involving accelerated particles. Instantaneous time-dependent charge states of silicon and oxygen were calculated and used to synthesize the instantaneous and period-averaged spectra of Si IV and O IV. The electron beam drives the plasma out of equilibrium. At electron densities of N-e = 10(10) cm(-3), the plasma is out of ionization equilibrium at all times in all cases we considered, while for a higher density of N-e = 10(11) cm(-3), ionization equilibrium can be reached toward the end of each period, depending on the conditions. In turn, the character of the period-averaged synthetic spectra also depends on the properties of the beam. While the case of kappa = 2 results in spectra with strong or even dominant O IV, higher values of kappa can approximate a range of observed TR spectra. Spectra similar to typically observed spectra, with the Si IV 1402.8 angstrom line about a factor 5 higher than O IV 1401.2 angstrom, are obtained for kappa = 3. An even higher value of kappa = 5 results in spectra that are exclusively dominated by Si IV, with negligible O IV emission. This is a possible interpretation of the TR spectra of UV (Ellerman) bursts, although an interpretation that requires a density that is 1-3 orders of magnitude lower than for equilibrium estimates.nn

Název v anglickém jazyce

Non-equilibrium ionization by a periodic electron beam II. Synthetic Si IV and O IV transition region spectra

Popis výsledku anglicky

To investigate the combination of non-equilibrium ionization and high-energy particles, we apply the model of the periodic electron beam, represented by a kappa-distribution that recurs at periods of several seconds, to plasma at chromospheric temperatures of 10(4) K. This simple model can approximate a burst of energy release involving accelerated particles. Instantaneous time-dependent charge states of silicon and oxygen were calculated and used to synthesize the instantaneous and period-averaged spectra of Si IV and O IV. The electron beam drives the plasma out of equilibrium. At electron densities of N-e = 10(10) cm(-3), the plasma is out of ionization equilibrium at all times in all cases we considered, while for a higher density of N-e = 10(11) cm(-3), ionization equilibrium can be reached toward the end of each period, depending on the conditions. In turn, the character of the period-averaged synthetic spectra also depends on the properties of the beam. While the case of kappa = 2 results in spectra with strong or even dominant O IV, higher values of kappa can approximate a range of observed TR spectra. Spectra similar to typically observed spectra, with the Si IV 1402.8 angstrom line about a factor 5 higher than O IV 1401.2 angstrom, are obtained for kappa = 3. An even higher value of kappa = 5 results in spectra that are exclusively dominated by Si IV, with negligible O IV emission. This is a possible interpretation of the TR spectra of UV (Ellerman) bursts, although an interpretation that requires a density that is 1-3 orders of magnitude lower than for equilibrium estimates.nn

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10308 - Astronomy (including astrophysics,space science)

Projekt

—

Návaznosti

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2018

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Astronomy & Astrophysics

ISSN

1432-0746

e-ISSN

—

Svazek periodika

610

Číslo periodika v rámci svazku

March

Stát vydavatele periodika

FR - Francouzská republika

Počet stran výsledku

12

Strana od-do

—

Kód UT WoS článku

000427139000005

EID výsledku v databázi Scopus

2-s2.0-85042885763