An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 457
heiligenschein
  سپنت‌فروغ   
sepant foruq

Fr.: auréole, heiligenschein   

A diffuse bright region surrounding the shadow that an observer's head casts on an irregular surface. It can be best observed on dewy reeds or grass. This phenomenon is reminiscent of the → glory, but without its color and regular structure.

Heiligenschein, Ger., literally "saint's shining light," from heiligen, from heilig "holy, sacred" (P.Gmc. *khailagas; M.H.G. heilec; O.H.G. heilag; Goth. hailag; O.N. heilagr; O.E. halig; E. holy) + Schein "glow, shine" (M.H.G. schinen, O.H.G. skinan, P.Gmc. *skinanan; E. shine; cf. Mod.Pers. sâyé "shadow;" Mid.Pers. sâyak "shadow;" Av. a-saya- "throwing no shadow;" Skt. chāya- "shadow;" Gk. skia "shade;" Rus. sijat' "to shine;" PIE base *skai- "bright").

Sepant foruq, from sepant "holy" (Mid.Pers. spand "holy," Spandarmat "Holy Thought; 5-th day of the month; 12-th month of the year;" from Av. spənta- "holy; beneficent," spəntô.mainyav- "coming from or belonging to the holy spirit," spəntô.təma- "holiest") + foruq "light, brightness" (related to rôšan "light; bright, luminous;" ruz "day," afruxtan "to light, kindle;" Mid.Pers. payrog "light, brightness," rošn light; bright," rôc "day;" O.Pers. raucah-; Av. raocana- "bright, shining, radiant," raocah- "light, luminous; daylight;" cf. Skt. rocaná- "bright, shining, roka- "brightness, light;" Gk. leukos "white, clear;" L. lux "light" (also lumen, luna; E. light, Ger. Licht, and Fr. lumière; PIE base *leuk- "light, brightness").

heir
  ریگن‌مند، ریگنمند   
riganmand

Fr.: héritier   

A person who inherits or has a right of inheritance in the property of another following the latter's death (Dictionary.com).

heritage.

Heisenberg uncertainty principle
  پَروز ِ ناتاشتیگی ِ هایزنبرگ   
parvaz-e nâtâštigi-ye Heisenberg

Fr.: principe d'incertitude de Heisenberg   

The uncertainty in the measurement of the position and momentum of an elementary particle. The more precisely one quantity is known, the less certain the precision of the other. A similarly linked pair of quantities is the time and energy content in a volume of space.

Named after Werner Heisenberg (1901-1976), the German physicist who in 1927 derived the uncertainty principle. In 1932 he was awarded the Nobel Prize in Physics; uncertainty, from → un- "not" + → certainty; → principle.

heliacal
  هورانه   
hurâné

Fr.: héliaque   

Of or near the → Sun, especially rising and setting with the Sun. → heliacal rising, → heliacal setting.

Heliacal "pertaining to the sun," from Gk. heliakos "of the sun," from helios, → sun; cognate with Pers. hur, as below.

Hurâné "sunlike," since the star rises in the morning like the Sun, from hur "sun", variant xor; Mid.Pers. xvar "sun;" Av. hû-, hvar- "sun;" Skt. surya-; L. sol; O.H.G. sunna; Ger. Sonne; E. sun; PIE *sawel- "sun" + -âné similarity suffix.

heliacal rising
  بر‌آیش ِ هورانه   
barâyeš-e hurâné

Fr.: lever héliaque   

The first appearance of a star following a period of invisibility due to its conjunction with the Sun. → heliacal rising of Sirius.

heliacal; → rising.

heliacal rising of Sirius
  بر‌آیش ِ هورانه‌ی ِ تیشتر   
barâyeš-e hurâne-ye Tištar

Fr.: lever héliaque de Sirius   

The first rising of → Sirius at dawn shortly before → sunrise. The heliacal rising of Sirius played a significant role in ancient Egypt by heralding the annual flooding of the Nile. The event took place some 70 days after the star had been seen for the last time in the western horizon at sunset. The heliacal rising of Sirius and its association with the rebirth of the Nile was so important that it marked the start of the Egyptian calendar year. At the time, the heliacal rising occurred in early July, as seen from the ancient capital of Memphis. But due to the → precession of the equinoxes the star now reappears in early August in Egypt. The date depends on the latitude (assuming transparent skies), being later for higher latitudes. For latitude 48° it occurs on about August 19.

heliacal; → rising; → Sirius.

heliacal setting
  فروشد ِ هورانه   
forušod-e hurâné

Fr.: coucher héliaque   

The last visible setting of a star below the western horizon just after sunset entering into a conjunction with the Sun.

heliacal; → setting.

helicity
  پیچاری   
picâri

Fr.: hélicité   

1) In particle physics, the projection of the spin of an elementary particle on the direction of momentum.
2) In fluid mechanics, → kinetic helicity.
3) In magnetohydrodynamics, → magnetic helicity.

From → helix + → -ity.

helio-
  هور-، خور-، خورشید-   
hur- (#), xor- (#), xoršid- (#)

Fr.: hélio-   

A combining form of Gk. helios "sun."

Helio-, combining form of from Gk. helios "sun;" cognate with Persian hur "sun", variant xor and xoršid (Av. hvarə-xšaēta- "shining sun"); Mid.Pers. xvar "sun;" Av. hû-, hvar- "sun;" Skt. surya-; L. sol; O.H.G. sunna; Ger. Sonne; E. sun; PIE *sawel- "sun."

heliocentric
  هورمرکزی، خورشیدمرکزی   
hurmarkazi (#), xoršid markazi (#)

Fr.: héliocentrique   

Having or representing the Sun as a center. → heliocentric cosmology, → heliocentric gravitational constant, → heliocentric Julian Day, → heliocentric parallax, → heliocentric system.

helio- + → center + → -ic.

heliocentric cosmology
  کیهان‌شناسی ِ هورمرکزی   
keyhânšenâsi-ye hurmarkazi (#)

Fr.: cosmologie héliocentrique   

A model of the Universe in which the Sun was centrally located.

heliocentric; → cosmology.

heliocentric gravitational constant
  پایای ِ گرانشی هورمرکزی   
pâyâ-ye gerâneši-ye hur-markazi

Fr.: constante gravitationnelle héliocentrique   

A parameter representing the product of the → gravitational constant by the → solar mass. It is 13.27 x 1019 m3 s-2.

heliocentric; → gravitational; → constant.

Heliocentric Julian Date
  گاهداد ِ ژولی‌ین ِ هورمرکزی   
gâhdâd-e žulian-e hurmarkazi

Fr.: date julienne héliocentrique   

The → Julian Date referenced to the center of the → Sun. Since the Earth revolves around the Sun, and since light travels at a finite speed, observations of a given object taken at different positions in the Earth's orbit are not equivalent, and so a correction for Earth's orbit around the Sun is required. Left uncorrected, the time of an observational event measured by Earth clocks will vary by 16.6 minute over the course of a year. If not properly accounted for, this can lead to a spurious signal in a → periodogram.

heliocentric; → Julian Date.

heliocentric parallax
  دیدگشت ِ هورمرکزی   
didgašt-e hurmarkazi

Fr.: parallaxe héliocentrique   

The parallax of a celestial body when viewed from two points in the Earth's orbit around the Sun. More specifically, the angular difference in a celestial object's position as seen from the center of the Sun and the center of the Earth. Also called → annual parallax.

heliocentric; → parallax.

heliocentric system
  راژمان ِ هورمرکزی   
râžmân-e hurmarkazi

Fr.: système héliocentrique   

A system in which the Sun is assumed to lie at its central point while the Earth and other bodies revolve around it.

heliocentric; → system.

heliogram
  هورنگاشت   
hurnegâšt (#)

Fr.: héliogramme   

A record made by a → heliograph.

helio-; + → -gram.

heliograph
  هورنگار   
hurnegâr (#)

Fr.: héliographe   

1) An instrument for photographing the Sun, consisting of a camera and a specially adapted telescope.
2) A simple device using a mirror to reflect sunlight to a distant observer. By moving the mirror, flashes of light can be used to send coded messages. The heliograph was a highly effective instrument for instantaneous optical communication over 80km or more in the 19th century.
3) Meteo.: An instrument which records the duration of sunshine and gives a quantitative measure of the amount of sunshine.

helio-; + → -graph.

heliometer
  هورسنج   
hursanj (#)

Fr.: héliomètre   

An instrument used to measure the angular separation of two stars that are too far apart to be included in the field of view of an ordinary telescope.  The instrument was originally designed for measuring the variation of the Sun's diameter at different seasons of the year.

helio- + → -meter.

heliopause
  هورمرز   
hurmarz

Fr.: héliopause   

The edge of the solar system where the pressure of the → solar wind balances that of the → interstellar medium plasma. In other words, the surface boundary that separates the → heliosphere from interstellar space. It is estimated to be situated 100 → astronomical units or more from the Sun. A → bow shock likely forms as the interstellar medium wind approaches the heliosphere and is deflected around the heliosphere, forcing it into a teardrop-shaped structure with a long, comet-like tail.

From → helio- + pause "break, cessation, stop," from M.Fr. pause, from L. pausa "a halt, stop, cessation," from Gk. pausis "stopping, ceasing," from pauein "to stop, to cause to cease."

Hurmarz, from hur, → helio-, + marz "frontier, border, boundary," → frontier.

helioseismology
  هورلرزه‌شناسی   
hurlarzešenâsi

Fr.: héliosismologie   

The branch of astrophysics that investigates the interior structure of the Sun by studying its surface wave oscillations. See also → asteroseismology and → stellar pulsation. The surface of the Sun vibrates much like a bell. A piano has 88 keys or musical tones, whereas the Sun has millions of notes. These vibrations are the result of internal pressure waves that reflect off the → photosphere and repeatedly cross the solar interior. They are detected through the → Doppler shift of absorption lines formed in the photosphere. Because these vibrations make the solar surface move up and down, analysis of the surface patterns is used to study conditions far below the Sun's surface. The mean period of the vibrations is about five minutes, which corresponds to a speed of 0.5 km s-1 or a frequency of about 3 mHz. See also → p mode.

From → helio- + → seismology.

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