Fr.: mélange thermohaline
In stars, an instability phenomenon, reminiscent of the → thermohaline convection in the oceans, that takes place when layers of higher molecular weight occur above a region of lower molecular weight. A situation of heavier material being above lighter gas in a star can occur during the → helium flash when → helium burning does not start in the center but in the shell. Similarly, in → close binary systems it may happen that helium-rich material is transferred to a → main sequence star. Then a helium-rich outer layer is formed and the instability occurs at the interface between that layer and the original stellar material. This process can explain several surface abundance variations in stars. First discussed by S. Kato (1966, Publ. Astron. Soc. Japan 18, 374).
Fr.: flash thermonucléaire
A theoretical interpretation for the → X-ray bursts observed toward → low-mass X-ray binary (LMXB) stars. According to models, X-ray bursts are produced on the surface of → neutron stars as a result of violent thermonuclear processes in a → hydrogen or → helium rich → layer. It is the → nuclear energy released in the → fusion of hydrogen and helium to heavier elements (e.g., Ni, Zn, and Se) in the → accreted matter which heats the upper layers of the neutron star so that X-rays are emitted from the surface (see, e.g., Taam, R.E., 1984, AIP Conf. Proc. 115, 263).
vâžireš-e garmâhaste-yi (#)
Fr.: réaction thermonucléaire
A nuclear reaction in which two or more atomic nuclei fuse into a single heavier nucleus by a collision of the interacting particles at extremely high temperatures. Chains of thermonuclear reactions, such as the → proton-proton chain and the → CNO cycle, account for the energy radiated from the Sun and more massive stars.
vâžireš-e garmâhaste-yi-e legâm gosixté
Fr.: emballement thermonucléaire
Vâžireš, → reaction; garmâhaste-yi, → thermonuclear; legâm gosixté literally "rampant, unrestrained," from legâm "bridle, rein" + gosixté "broken off, torn away," p.p. of gosixtan "to tear away, to break off."
Fr.: supernova thermonucléaire
Same as → type Ia supernova
The region of the upper atmosphere in which temperature increases continuously with height, starting at roughly 100 km. The thermosphere includes the exosphere and most of the ionosphere.
A device for maintaining a system at constant temperature by automatically terminating or restoring the heating or cooling source. It consists of a temperature sensing instrument connected to a switching device. The sensing device is often a bimetallic strip which triggers a simple electric switch.
1) A controlled and structured list of terms or descriptors usually
with a cross-reference system used in subject analysis and information
retrieval in a particular field.
From L. thesaurus "treasury, treasure," from Gk. thesauros "treasure, treasury, storehouse," from root of tithenai "to put, to place," → thesis.
Vâžganj, from vâž, → word, + ganj "treasure," from Mid.Pers. ganj "treasure."
1) dâyeš; 2) dâyeš-nâmé, pâyân-nâmé
1) A proposition put forward for consideration, especially one to be
discussed and proved or to be maintained against objections.
M.E., from L., from Gk. thesis "a proposition; a setting down, something set down," from root of tithenai "to place, put, set," cognate with Pers. dâdan "to give," as below.
1) Dâyeš "giving, setting down," from
O.Pers./Av. dā- "to give, grant, put,"
dadāiti "he gives;" Mid.Pers./Mod.Pers.
dâdan "to give; to put"
(cf. Skt. dadáti "he gives;"
Gk. tithenai "to place, put, set," didomi "I give;"
L. dare "to give, offer;"
Rus. delat' "to do;" O.H.G. tuon, Ger. tun,
O.E. don "to do;" PIE base *dhe- "to put, to do")
+ -y- epenthetic vowel + -eš verbal noun suffix.
In Greek and Roman mythology, Thestias was the patronym of Leda, → Pollux's mother.
Relatively great in extent from one surface to the opposite; deep or profound. &rarroptically thick
M.E. thikke, O.E. thicce "not thin, dense," from P.Gmc. *theku-, *thekwia- (cf. O.S. thikki, O.H.G. dicchi, Ger. dick), from PIE *tegu- "thick."
Setabr, from Mid.Pers. stabr "strong, big," stambag "pugnacious, opposing;" O.Pers. (mā) stabava [2sg.inj.] "to revolt;" Av. stabra- "strong, firm;" cf. Skt. stabh- "support," stambh- "to support, fix firmly," stabhnāti "supports;" Gk. astemphes "steadfast," stephein "to tie around, encircle," astemphes "firm, rigid;" Lith. stebas "staff, pillar," stembti "to oppose."
gerde-ye setabr, disk-e ~
Fr.: disque épais
A disk component of a → spiral galaxy that lies above the → thin disk and mainly consists of stars. The thick disk of our → Galaxy makes up about 10-50% of the stellar mass of the → Milky Way and has a scale height of ~ 1,000-3,000 → light-years. Thick disk stars are, on average, moving faster in a vertical direction with respect to the → galactic plane than thin disk stars. In contrast to thin disk, the stars within the thick disk are almost all older than 10 billion years and typically have a smaller → metallicity than the average values for the thin disk stars. These facts suggest that the formation scenarios for the thin and thick disks were different. In particular, it is thought that the thick disk is much older than the thin disk.
Fr.: lentille épaisse
A lens whose thickness is not small compared with its focal length. The thick lens may include several components, which may or may not be in contact. → thin lens.
The state or quality of being thick. → optical thickness.
M.E. thiknesse, O.E. thicnes, from → thick + -nes(s) suffix of action, quality or state, cf. M.Du. -nisse, O.H.G. -nissa, Ger. -nis, Goth. -inassus.
Setabrâ, from setabr→ thick + -â a suffix forming nouns from adjectives.
M.E. thi, thigh(e), the(h), O.E. thioh, theoh; cognate with Du. dij, O.H.G. dioh, O.Norse thjo.
Rân, from Mid.Pers. rân "thigh;" Av. rāna- "the outer part of the thigh."
M.E. thyn(ne), O.E. thynne, from P.Gmc. *thunnuz, *thunw- (cf. W.Fris. ten, M.L.G. dunne, Du. dun, O.H.G. dunni, Ger. dünn), from PIE *tnus-, *tnwi-, from base *ten- "stretch;" cf. Pers. tonok "thin, slender," → attenuate.
Nâzok, from Mid.Pers. nâzuk, nâzik "tender, gentle."
gerder-ye nâzok, disk-e ~
Fr.: disque mince
A disk component of a → spiral galaxy containing → stars, → gas, and → dust which are confined to the galaxy's → plane of rotation. In contrast to → thick disks, thin disks contain the bulk of the → baryonic matter in spiral galaxies. For example, on the order of 60-90% of the baryonic matter in the → Milky Way is located in the thin disk. The scale height of the thin disk in the Milky Way is about 400 → light-years, whereas its scale length is about 10,000 light-years. Moreover, the outer regions of thin disks appear to be bent by the → warp phenomenon. The thin disks of spiral galaxies are active sites of → star formation, especially in the spiral arms. For this reason, stars in the thin disk tend to be relatively young. Thin disk stars also tend to be → metal-rich compared with thick disk and → halo stars, and typically have a → metallicity similar to that of the Sun.
adasi-ye nâzok (#)
Fr.: lentille mince
A lens whose thickness is considered small in comparison with the distances generally associated with its optical properties. Such distances are, for example, radii of curvature of the two spherical surfaces, primary and secondary focal lengths, and object and image distances. → thick lens.
1) A material object without life or consciousness; an inanimate object.
M.E. thing; O.E. þing "meeting, assembly, discussion;" cf. O.Norse þing "assembly, meeting, council;" O.Frisian thing "assembly, action, matter, thing;" O.Saxon thing; O.Du. dinc "law suit, matter, thing;" M.Du. ding; Du. ding; O.Ger. ding, dinc "assembly;" M.H.G. dinc "assembly;" Ger. ding "matter, affairs, thing." Hence, the word originally meant "assembly, meeting," then came to mean a specific issue discussed at such an assembly, and finally came to indicate "an object."
Ciz, from Mid.Pers. ciš, tis "thing, affair;" O.Pers. cišciy "anything."
Fr.: penser, réfléchir
To employ one's mind rationally and objectively in evaluating or dealing with a given situation.
M.E. thinken, variant of thenken, O.E. thencan; P.Gmc. *thankjan (cf. O.Fris. thinka, O.S. thenkian, O.H.G. denchen, Ger. denken, Goth. thagkjan).
Andišidan, infinitive from andiš-; Mid.Pers. handeš-, handešidan "to think, consider, reflect," ultimately from Proto-Iranian *ham-dis-, from *ham- "together, with, same," → syn- + *dis- "form, appearance," cf. Av. daēs- "to show," daēsa- "sign, omen;" Mod.Pers. dis, disé "form, appearance," variants -diz, -diš; Mid.Pers. dêsag "form, appearance," dêsidan "to form, build;" Sogd. andiš "to seem," andêš "to show," andêšik "appearing;" cf. Skt. deś- "to show, point out;" PIE *deik- "to show" (cf. Gk. deiknumi "to show," dike "manner, custom;" L. dicere "to utter, say;" O.H.G. zeigon, Ger. zeigen "to show;" O.E. teon "to accuse," tæcan "to teach").