An Etymological Dictionary of Astronomy and Astrophysics
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فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 13 Search : spot
follower spot
  لکه‌ی ِ پیرو   
lake-ye peyrow

Fr.: tache de queue   

A → sunspot that follows the → leader spot. Sunspots tend to appear in groups consisting of one leader and several follower spots. The leader and the follower spots having opposite polarities.

Agent noun of follow, from O.E. folgian, fylgan "to follow, pursue," from W.Gmc. *fulg- (cf. O.Fris. folgia, M.Du. volghen, Ger. folgen "to follow").

Laké, → spot; peyrow "follower," from pey "step; after," related to "foot, step, track," → foot, + row "going; which goes," present stem of raftan "to go, walk, proceed," Mid.Pers. raftan, raw-, Proto-Iranian *rab/f- "to go; to attack."

Great Red Spot
  لکه‌ی ِ سرخ ِ بزرگ   
lakke-ye sorx-e bozorg (#)

Fr.: Grande tache rouge   

An anticyclonic storm on the planet Jupiter akin to a hurricane on Earth, but it is enormous (three Earths would fit within its boundaries) and it has persisted for at least the 400 years that humans have observed it through telescopes.

great; → red; → spot.

hot spot
  لکه‌ی ِ داغ   
lekke-ye dâq (#)

Fr.: point chaud   

A compact, highly luminous region in a cataclysmic binary located in the accretion disk where the stream of material hits it.

hot; → spot.

leader spot
  لکه‌ی ِ پیشرو   
lakke-ye pišrow (#)

Fr.: tache de tête   

In a → sunspot group, the first spot to form in the direction of rotation and the last to disappear. It is the largest, the strongest in magnetic intensity, and the closest to the solar equator among the group sunspots. See also → follower spot.

From M.E. leder(e), O.E. lædan "cause to go with one, lead," from W.Gmc. *laithjan (cf. O.S. lithan, O.N. liða "to go," O.H.G. ga-lidan "to travel," Goth. ga-leiþan "to go"); → spot.

Lakké, → spot; pišrow "leader, forerunner," from piš "in front, forward, before" (Mid.Pers. pêš "before, earlier;" O.Pers. paišiya "before; in the presence of") + row "going," present stem of raftan "to go, elapse, glide by, depart" (Mid.Pers. raftan, raw-, Proto-Iranian *rab/f- "to go; to attack").

on-the-spot (OTS) approximation
  نزدینش ِ درجا   
nazdineš-e darjâ

Fr.:   

An approximation in the treatment of photoionized → H II regions, whereby secondary ionizing photons are absorbed immediately very close to their site of emission. The secondary photons, produced by → radiative recombinations directly to the → ground states, are thus ignored with respect to the ionizing photons emitted by the → exciting star. The OTS approximation requires that the ionized gas be sufficiently dense so that secondary ionizing photons are very likely absorbed within the H II region.

on; → spot; → approximation.

Nazdineš, → approximation; dar "in," from Mid.Pers. andar, → intra-.

Red Spot
  لکه‌ی ِ سرخ   
lakke-ye sorx (#)

Fr.: Tache rouge   

See → Great Red Spot, on Jupiter.

red; → spot.

relative sunspot number
  شمار ِ بازانی ِ هورلک   
šomâr-e bâzâni-ye hurlak

Fr.: nombre relatif de taches solaires   

Same as → Wolf number and → sunspot number.

relative; → sunspot; → number.

spot
  لک، لکه   
lak (#), laké (#)

Fr.: tache   

A mark on a surface differing sharply in color from its surroundings. → sunspot; → Great Red Spot.

M.E. spotte "a spot, blot, patch;" M.Du. spotte "spot, speck."

Lak(k), lak(k)é "spot, stain."

starspot
  ستاره-لک   
setâre-lak

Fr.: tache stellaire   

A phenomenon similar to a → sunspot but occurring on the surface of a star other than Sun. Due to spatial resolution constraints, starspots so far observed are in general much larger than those on the Sun, up to about 30% of the stellar surface may be covered, corresponding to sizes 100 times greater than those on the Sun.

star; → spot.

sunspot
  هورلک   
hurlak (#)

Fr.: tache solaire   

An area seen as a dark patch on the Sun's surface. Sunspots appear dark because they are cooler (of about 4000 °C) than the surrounding → photosphere (about 6000 °C). They range in size from a few hundred kilometers to several times the Earth's diameter and last from a few hours to a few months. Very small sunspots are called → pores. The number of sunspots varies from maximum to minimum in about 11 years, the → sunspot cycle. Their appearance during a cycle follows the → Sporer law. A typical spot has a central → umbra surrounded by a → penumbra, although either features can exist without the other. Sunspots are associated with strong magnetic fields of 0.2 to 0.4 → tesla. A given sunspot has a single magnetic → polarity. The opposite polarity may be found in other sunspots or in the bright and diffuse → facular region adjacent to the sunspot. The first recorded naked-eye sightings of sunspots were by Chinese astronomers in the first century B.C. Johannes Fabricius (1587-1617) was the first to argue that sunspots are areas on the solar surface.

Sun; → spot.

sunspot cycle
  چرخه‌ی ِ هورلک   
carxe-ye hurlak

Fr.: cycle des taches solaires   

solar cycle.

sunspot; → cycle.

sunspot minimum
  کمینه‌ی ِ هورلک   
kamine-ye hurlak

Fr.: minimum des taches   

Periods of time when the → relative sunspot number is low. These periods of time occur approximately every 11 years and represent the minimum in the → sunspot cycle.

sunspot; → minimum.

sunspot number
  شمار ِ هورلک   
šomâr-e hurlak

Fr.: nombre de taches, ~ ~ Wolf   

A quantity which gives the number of sunspots at a given time. It is defined by the relationship R = k(10g + f), where R is the sunspot number, k is a constant depending on the observation conditions and the instrument used, g is the number of the groups and f is the number of individual spots that can be counted. Also called the → Wolf number and → relative sunspot number.

sunspot; → number.