Non-LTE Calculation of the Ni I 676.8 Nanometer Line in a Flaring Atmosphere

Details Non-LTE Calculation of the Ni I 676.8 Nanometer Line in a Flaring Atmosphere Non-LTE Calculation of the Ni I 676.8 Nanometer Line in a Flaring Atmosphere

Sep 2002

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2002apj...576l..83d&link_type=abstract

The Astrophysical Journal, Volume 576, Issue 1, pp. L83-L86.

Astronomy and Astrophysics

Astronomy

37

Line: Profiles, Sun: Activity, Sun: Atmosphere, Sun: Flares

Scientific paper

The Ni I 676.8 nm line is used by the Solar and Heliospheric Observatory Michelson Doppler Imager to measure the magnetic field and velocity field in the solar atmosphere. We make non-LTE calculations of this line in an atmosphere that is bombarded by an energetic electron beam. This case is associated with the occurrence of solar flares. The electron beam produces nonthermal ionization and excitation of the hydrogen atoms and redistributes the level populations. This results in an enhanced opacity near the Ni I line and an upward shift of its formation height, as well as an increased line source function. We find that the Ni I line may appear in emission in the presence of a fairly strong electron beam and preferentially in a cool atmosphere (i.e., sunspot umbrae/penumbrae). On the other hand, if there is no bombarding electron beam, the profile can hardly turn to emission even though the atmosphere may be heated to higher temperatures through other ways. This result implies that the sign reversal of the longitudinal magnetic field observed in some flare events may not be a true reversal but just an artifact associated with the production of an emission profile.

Affiliated with

Also associated with

No associations

Rating

Non-LTE Calculation of the Ni I 676.8 Nanometer Line in a Flaring Atmosphere does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Non-LTE Calculation of the Ni I 676.8 Nanometer Line in a Flaring Atmosphere, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Non-LTE Calculation of the Ni I 676.8 Nanometer Line in a Flaring Atmosphere will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1311622