Spicule


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Related to Spicule: spongin

spicule:

see chromospherechromosphere
[Gr.,=color sphere], layer of rarefied, transparent gases in the solar atmosphere; it measures 6,000 mi (9,700 km) in thickness and lies between the photosphere (the sun's visible surface) and the corona (its outer atmosphere).
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Spicule

 

Spicules are spike-like prominences visible at the limb of the sun during solar eclipses or during observation of the sun in monochromatic light, for example, the light of the hydrogen line Hλ. They extend into the solar corona to heights of 6,000–10,000 km and have diameters of 200–2,000 km. The average lifetime of a spicule is 5–7 min. Spicules move upward at speeds of 20–30 km/sec; the speeds of internal movements are 5–10 km/sec. The temperature of a spicule is approximately 8000°K in the lower part and about 16,000°K in the upper part. The density of spicules varies with height from 2 × 1011 to 3 × 1010 atoms/cm3. Hundreds of thousands of spicules exist on the sun at one time. They arise primarily at the edges of the cells of the chromospheric network.


Spicule

 

(1) In certain invertebrates a skeletal element consisting of calcium carbonate or, less commonly, silica (silicon dioxide). Spicules occur in sponges (in the form of one-, three-, four-, and many-rayed needles), octocorallians, aplacophorans, mollusks, holothurians and other echinoderms (in the form of small wheels, anchors, or lattices), and ascidians (in the form of thorny spheres).

(2) In nematodes, a part of the male copulatory organ. In some species the spicules are supplementary formations; they protrude from the cloacal opening of the male and serve to widen the female’s vagina. In other species sulcate spicules come together and conduct the spermatozoa into the vagina of the female.

spicule

[′spik·yül]
(astronomy)
One of an irregular distribution of jets shooting up from the sun's chromosphere. Also known as solar spicule.
(botany)
An empty diatom shell.
(invertebrate zoology)
A calcareous or siliceous, usually spikelike supporting structure in many invertebrates, particularly in sponges and alcyonarians.
References in periodicals archive ?
Precloca or species Spicule length(p) midventral fans affinis 220-230 6 cahirensis 170 7 splindida 207 8 author's 275 8 specimen
At first glance, spicules are thought to have a magnetic origin, as these fields seem to flood the chromosphere [148, 150, 206-215].
Scientists led by Wolfgang Tremel, a professor at Johannes Gutenberg Universitat Mainz, built the artificial spicules by mixing silicatein-[alpha] with calcite.
The beginning of the next transgressive sedimentation cycle in the uppermost Lower Artinskian could be correlated with the upper part of the Gipshuken Formation, where brachiopods (in situ), bryozoans, and sponge spicules give evidence of open marine influx of temperate water conditions (Ezaki & Kawamura 1992).
dagger]) Proponents of these models have expressed that two classes of spicules exist.
Thick-bedded Limestone, yellow weathered to buff color having radiolaria and sponge spicule
However, in contrast, a recent study found a downregulation for a suite of genes involved in spicule formation and skeletogenesis for urchin larvae (S.
The short antennal segment I that is less than the head width and the shape of the endosomal spicule are roughly similar in the new North American species and these two Old World taxa.
High-resolution computed tomography (CT) of the temporal bones showed significant ossicular displacement; no evidence of a fracture or penetrating bony spicule involving the tympanic segment of the facial nerve was found (figure).
The left spicule (length 378 [micro]m), with a handle and lamina of equal length, was similar to that of D.
Research in the 1980s found that spicule plasma did not reach coronal temperatures but in 2007, Bart De Pontieu, the lead author and a solar physicist at LMSAL, and McIntosh identified a new class of spicules that shoot upward at high speeds, often in excess of 60 miles per second (100 kilometers per second), before disappearing.