Editing Sungrazing comet (section)

==== Coronagraphic observations ====
The 20th century greatly impacted sungrazing comet research with the launch of [[coronagraphic]] telescopes including [[P78-1|Solwind]], [[Solar Maximum Mission|SMM]], and [[Solar and Heliospheric Observatory|SOHO]].  Until this point, sungrazing comets were only seen with the [[naked eye]] but with the coronagraphic telescopes many sungrazers were observed that were much smaller and very few have survived perihelion passage.  The comets observed by Solwind and SMM from 1981 to 1989 had [[Apparent magnitude|visual magnitudes]] from about -2.5 to +6 which is much fainter than Comet Ikeya-Seki with a visual magnitude of about -10.<ref name=Marsden />

In 1987 and 1988 it was first observed by SMM that there could be pairs of sungrazing comets that can appear within very short time periods ranging from a half of a day up to about two weeks. Calculations were made to determine that the pairs were part of the same parent body but broke apart at tens of AU from the Sun.<ref>{{cite journal|last=Sekanina|first=Zdenek|title=Secondary Fragmentation of the ''Solar and Heliospheric Observatory'' Sungrazing Comets at Very Large Heliocentric Distance|journal=The Astrophysical Journal|date=20 October 2000|volume=542|issue=2|pages=L147–L150|doi=10.1086/312943|bibcode=2000ApJ...542L.147S|s2cid=122413384|doi-access=free}}</ref> The breakup velocities were only on the order of a few meters per second which is comparable to the speed of rotation for these comets. This led to the conclusion that these comets break from [[tidal force]]s and that comets C/1882 R1, C/1965 S1, and C/1963 R1 probably broke off from the Great Comet of 1106.<ref>{{cite journal|last=Sekanina|first=Zdenek|author2=Chodas, Paul W. |title=Common Origin of Two Major Sungrazing Comets|journal=The Astrophysical Journal|date=10 December 2002|volume=581|issue=1|pages=760–769|doi=10.1086/344216|bibcode=2002ApJ...581..760S|doi-access=free}}</ref>

Coronagraphs allowed for measuring the properties of the comet as it reached very close to the Sun.  It was noted that sungrazing comets tend to peak in brightness at a distance of about 12.3 [[Solar radius|solar radii]] or 11.2 solar radii.  It is thought that this variation stems from a difference in dust composition.  Another small peak in brightness has been found at about 7 solar radii from the sun and it is possibly due to a fragmentation of the comet nucleus.<ref name=Marsden /> An alternative explanation is that the brightness peak at 12 solar radii comes from the sublimation of [[Amorphous solid|amorphous]] [[olivine]]s and the peak at 11.2 solar radii is from the sublimation of [[Crystallinity|crystalline]] olivines.  The peak at 7 solar radii could then be the [[Sublimation (phase transition)|sublimation]] of [[pyroxene]].<ref>{{cite journal|last=Kimura|first=H|title=Dust Grains in the Comae and Tails of Sungrazing Comets: Modeling of Their Mineralogical and Morphological Properties|journal=Icarus|date=October 2002|volume=159|issue=2|pages=529–541|doi=10.1006/icar.2002.6940|bibcode=2002Icar..159..529K}}</ref>