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Titolo:
EUV SPECTROSCOPY OF THE SUNSPOT REGION NOAA-7981 USING SOHO-II - VELOCITIES AND LINE-PROFILES
Autore:
BRYNILDSEN N; BREKKE P; FREDVIK T; HAUGAN SVH; KJELDSETHMOE O; MALTBY P; HARRISON RA; PIKE CD; RIMMELE T; THOMPSON WT; WILHELM K;
Indirizzi:
UNIV OSLO,INST THEORET ASTROPHYS OSLO NORWAY RUTHERFORD APPLETON LAB,DEPT SPACE SCI DIDCOT OX11 0QX OXON ENGLAND NATL SOLAR OBSERV SUNSPOT NM 88349 APPL RES CORP LANDOVER MD 20785 MAX PLANCK INST AERON D-37191 KATLENBURG DUHM GERMANY
Titolo Testata:
Solar physics
fascicolo: 2, volume: 179, anno: 1998,
pagine: 279 - 312
SICI:
0038-0938(1998)179:2<279:ESOTSR>2.0.ZU;2-A
Fonte:
ISI
Lingua:
ENG
Soggetto:
CORONA TRANSITION REGION; HIGH-RESOLUTION TELESCOPE; QUIET-SUN CONNECTION; SOLAR OBSERVATORY 8; IV RESONANCE LINES; FLUID MOTIONS; OBSERVED REDSHIFTS; DOPPLER-SHIFT; MASS MOTIONS; CHROMOSPHERE;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
96
Recensione:
Indirizzi per estratti:
Citazione:
N. Brynildsen et al., "EUV SPECTROSCOPY OF THE SUNSPOT REGION NOAA-7981 USING SOHO-II - VELOCITIES AND LINE-PROFILES", Solar physics, 179(2), 1998, pp. 279-312

Abstract

We have studied the dynamics in the sunspot transition region betweenthe chromosphere and the corona and investigated the extension of theBow field into the corona. Based on EUV spectra of a medium size sunspot and its surroundings, NOAA 7981, observed with CDS and SUMER on SOHO, we derive line-of-sight velocities and study the line profiles fora series of emission lines. The flow field in the low corona is foundto differ markedly from that in the transition region. In the transition region the relative line-of-sight velocity shows ar. upflow in theumbra and relatively large areas with downflow that cover part of thepenumbra. The spatial extent of these arf:as with upflow and downflowincreases with increasing temperature in the transition region, but the whole Bow field changes character as the temperature increases fromthe upper transition region to the low corona. Based on a calibrationof the SUMER wavelength scale we find that the entire sunspot transition zone appears to be moving downwards towards the chromosphere. The relation between this finding and the general tendency for transition-region lines to show a net red shift is discussed, Several of the transition-region spectral line profiles are observed to show two line components with Gaussian shape and line-of-sight velocities that differ markedly. Several of the line profiles that are composed of two spectral line components occur close to the dividing line between up-and downflow. A discussion of this observation is presented. In small regions with spatial extent of a few are sec we detect enhanced continuum emission underlying explosive events. The similarities between explosive events with continuum emission and the moustaches observed in H alpha close to sunspots are so striking that we are tempted to introduce the notation 'transition-region moustaches'.

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Documento generato il 27/09/20 alle ore 01:02:34