Spicule (solar physics)
Encyclopedia
Solar physics
For the physics journal, see Solar Physics Solar physics is the study of our Sun. It is a branch of astrophysics that specializes in exploiting and explaining the detailed measurements that are possible only for our closest star...
, a spicule is a dynamic jet of about 500 km diameter in the chromosphere
Chromosphere
The chromosphere is a thin layer of the Sun's atmosphere just above the photosphere, roughly 2,000 kilometers deep....
of the Sun
Sun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...
. It moves upwards at about 20 km/s from the photosphere
Photosphere
The photosphere of an astronomical object is the region from which externally received light originates. The term itself is derived from Ancient Greek roots, φῶς, φωτός/phos, photos meaning "light" and σφαῖρα/sphaira meaning "sphere", in reference to the fact that it is a spheric surface perceived...
. They were discovered in 1877 by Father Angelo Secchi
Angelo Secchi
-External links:...
of the Vatican Observatory
Vatican Observatory
The Vatican Observatory is an astronomical research and educational institution supported by the Holy See. Originally based in Rome, it now has headquarters and laboratory at the summer residence of the Pope in Castel Gandolfo, Italy, and an observatory at the Mount Graham International...
in Rome.
Description
Spicules live for about 5–10 minutes; at the solar limb they appear elongated (if seen on the disk, they are known as "mottles" or "fibrils"). They are usually associated with regions of high magnetic flux; their mass flux is about 100 times that of the solar windSolar wind
The solar wind is a stream of charged particles ejected from the upper atmosphere of the Sun. It mostly consists of electrons and protons with energies usually between 1.5 and 10 keV. The stream of particles varies in temperature and speed over time...
.
Prevalence
At any one time there are around 60,000 to 70,000 active spicules on the Sun; an individual spicule typically reaches 3,000-10,000 km altitude above the photosphere.Causes
Bart De Pontieu (Lockheed Martin Solar and Astrophysics Laboratory, Palo Alto, CaliforniaPalo Alto, California
Palo Alto is a California charter city located in the northwest corner of Santa Clara County, in the San Francisco Bay Area of California, United States. The city shares its borders with East Palo Alto, Mountain View, Los Altos, Los Altos Hills, Stanford, Portola Valley, and Menlo Park. It is...
), Robert Erdélyi and Stewart James (both from the University of Sheffield
University of Sheffield
The University of Sheffield is a research university based in the city of Sheffield in South Yorkshire, England. It is one of the original 'red brick' universities and is a member of the Russell Group of leading research intensive universities...
, Sheffield, UK) hypothesised in 2004 that spicules formed as a result of P-mode oscillations
Helioseismology
Helioseismology is the study of the propagation of wave oscillations, particularly acoustic pressure waves, in the Sun. Unlike seismic waves on Earth, solar waves have practically no shear component . Solar pressure waves are believed to be generated by the turbulence in the convection zone near...
in the Sun's surface, sound waves with a period of about five minutes that causes the Sun's surface to rise and fall at several hundred meters per second (see helioseismology
Helioseismology
Helioseismology is the study of the propagation of wave oscillations, particularly acoustic pressure waves, in the Sun. Unlike seismic waves on Earth, solar waves have practically no shear component . Solar pressure waves are believed to be generated by the turbulence in the convection zone near...
). Magnetic flux tubes that tilted away from the vertical can focus and guide the rising material up into the solar atmosphere to form a spicule. There is still however some controversy about the issue in the solar physics community.
Literature
- De Pontieu, B., Erdélyi, R. and James, S: Solar chromospheric spicules from the leakage of photospheric oscillations and flows In: Nature. 430/2004, p. 536–539,
In popular culture
In the video game Star Ocean 2, there is a famous attack skill called "Spicule" done by Decus (or Michael in the PlayStation PortablePlayStation Portable
The is a handheld game console manufactured and marketed by Sony Corporation Development of the console was announced during E3 2003, and it was unveiled on , 2004, at a Sony press conference before E3 2004...
version), one of the evil Ten Wise Men villains. He shoots a large pillar of fire upwards, and then yells a random taunt before coming down and bombarding the area with an explosion of fire, damaging the entire party immensely.
In the video game Bokosuka Wars
Bokosuka Wars
is a 1983 action-strategy role-playing video game developed by Kōji Sumii and released by ASCII for the Sharp X1 computer, followed by ports to the MSX, FM-7, NEC PC-6001, NEC PC-8801 and NEC PC-9801 computer platforms, as well as an altered version released for the Nintendo Famicom console and...
, there is an enemy named the "Spicule Man" who attacks the player using horizontal columns of fire.