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SUMMARY:On diversity of spectral shapes of hydrogen Lyman lines and Mg II 
 lines in a quiescent prominences
DTSTART;VALUE=DATE-TIME:20230509T154000Z
DTEND;VALUE=DATE-TIME:20230509T155500Z
DTSTAMP;VALUE=DATE-TIME:20240704T115653Z
UID:indico-contribution-306@meetings.aip.de
DESCRIPTION:Speakers: Pavol Schwartz (Astronomical Institute\, Slovak Acad
 emy of Sciences)\nA quiescent prominence was observed on October 22\, 2013
  quasi-simultaneously and nearly co-spatially in the Lyman series of hydro
 gen by SoHO/SUMER and in the Mg II h&k lines by IRIS. Such spectroscopic o
 bservations comprising multiple lines offer an excellent opportunity for d
 iagnostics of prominence plasma and the dynamics of its fine structures. H
 owever\, it also invokes significant challenges when compared with synthet
 ic spectra provided by radiative transfer modelling. Only a few similar co
 ordinated datasets of Lyman and Mg II h&k observations were ever obtained 
 in prominences. We present here the first spectroscopic analysis of this u
 nique dataset. Moreover\, for the first time\, we assess the influence of 
 noise on the statistics of profile characteristics. We focus on the follow
 ing characteristics – the number of distinct peaks\, integrated line int
 ensity\, center-to-peak ratio describing the depth of the reversal of two-
 peaked profiles\, and the asymmetry of peaks. There occur many profiles of
  both Lyman and Mg II lines which except of two major peaks\, contain also
  lower peaks – hereafter called as minor peaks. Nature of these\, possib
 ly spurious minor peaks is uncertain. They may be either due to noise or v
 igorous dynamics of the prominence. We show that noise has a negligible ef
 fect on the integrated intensities of all lines but it significantly affec
 ts the classification of spectral profiles using the number of distinct pe
 aks\, the reversal depth and also the peak asymmetry. We also demonstrate 
 that by taking into account an influence of noise\, we can assess which ch
 aracteristics of particular lines are suitable for diagnostics of differen
 t properties of prominence. For example\, we show that the minor peaks of 
 the Lyman line profiles are mostly caused by noise\, which means that only
  the dominant peaks should be used for statistical analyses or comparisons
  with synthetic spectra. On the other hand\, for Mg II k&h\, distinction b
 etween multi-peaked profiles with low peaks and profiles with deep reversa
 ls lies mainly in the dynamics of multiple fine structures located along a
  line of sight. The complex\, multi-peaked profiles are observed in places
  where multiple fine structures with different line-of-sight velocities ar
 e crossing the line of sight while the profiles with deep reversals likely
  correspond to instances when we observe single fine structure or multiple
  fine structures but with similar line-of-sight velocities. Such results l
 ead to a conclusion that if we are interested in the diagnostics of dynami
 cs of prominence fine structures\, the best approach is to use a combinati
 on of profile asymmetry in the Lyman lines together with the complex profi
 les of Mg II h&k lines. On the other hand\, if we want to diagnose the tem
 perature and pressure of individual prominence fine structures\, we need t
 o focus on deeply reversed Mg II h&k line profiles in combination with the
  Lyman lines and to analyse the depth of central reversal and the integrat
 ed intensity.\n\nhttps://meetings.aip.de/event/24/contributions/306/
LOCATION:Haus H\, Telegrafenberg
URL:https://meetings.aip.de/event/24/contributions/306/
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