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BEGIN:VEVENT
DTSTART;TZID=Atlantic/Canary:20110719T000000
DTEND;TZID=Atlantic/Canary:20110719T010000
UID:iactalks-298
X-WR-CALNAME: IAC Talks: Open Astronomy Seminars
X-ORIGINAL-URL: /iactalks/Talks/view/298
CREATED:2011-07-19T00:00:00+01:00
X-WR-CALDESC: IAC Talks upcomming talks
SUMMARY:M43, the little sister of the Orion Nebula
DESCRIPTION:M43, the little sister of the Orion Nebula\nDr. Sergio Simón D
 íaz, Dr. Jorge García Rojas\n\nWe have selected the Galactic HII region 
 M43, a close-by apparently  spherical nebula ionized by a single star (HD3
 7061, B0.5V) to investigate several topics of recent interest in the field
  of HII  regions and massive stars. We perform a combined, comprehensive s
 tudy of the nebula and its ionizing star by using as many observational co
 nstraints as possible. For this study we collected a set of high-quality o
 bservations, including the optical spectrum of HD3706,  along with nebular
  optical imaging and long-slit spatially resolved spectroscopy. On the one
  hand, we have carried out a quantitative spectroscopic analysis of the io
 nizing star from which we have determined the stellar parameters of HD3706
 1 and the total number of  ionizing photons emitted by the star; on the ot
 her hand, we have done a empirical analysis of the nebular images and spec
 troscopy from which we  have find observational evidence of scattered ligh
 t from the Huygens region (the brightest part of the Orion nebula) in the 
 M43 region. We  show the importance of an adequate correction of this scat
 tered light in both the imagery and spectroscopic observations of M43 in a
 ccurately  determining the total nebular Halpha luminosity, the nebular ph
 ysical conditions. and chemical abundances. We have computed total abundan
 ces  for three of the analyzed elements (O, S, and N), directly from obser
 vable ions (no ionization correction factors are needed). The  comparison 
 of these abundances with those derived from the spectrum of the Orion nebu
 la indicates the importance of the atomic data and,  specially in the case
  of M42, the considered ionization correction  factors.
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