An Etymological Dictionary of Astronomy and Astrophysics

A → Luminous Blue Variable star in the constellation → Carina; also known as HD 94910. AG Carinae lies about 6 kpc (20,000 → light-years) away and is surrounded by a → nebula. It is also a → spectroscopic variable, with the variability on time-scale of years. During the epochs of minimum in the visual → light curve (m_V ~ 8.1), the star is relatively hot and has a → WN11 spectral type, showing strong He I, H I, and N II → emission lines, weak He II 4686 Å emission, and Si IV 4088-4116 Å absorption. During the maximum epochs of the light curve (m_V ~ 6.0),
the star is cooler, and the spectrum is reminiscent of extreme A-type → hypergiants, with a strong emission of H I, Fe II, and T III lines. The transition between both phases is characterized by the appearance of peculiar features in the spectrum, such as absorption-line splitting, strong → electron-scattering wings in He I and Fe II lines, and apparent → inverse P Cygni profiles in He I lines.

The presence of a massive → bipolar nebula around AG Car testifies to a recent (t< 10⁴ years) phase of high → mass loss. The morphology and kinematics of the nebula suggest a → dynamical age of 8.5 × 10³ years and a high mass of → ionized nebular material (~ 4.2 Msun), which is likely composed of → ejecta from the central star. The nebular abundances show evidence of moderate nitrogen → enrichment. Properties of the → circumstellar nebula, studied in the → mid-infrared and → far-infrared, reveal an incredibly high dust mass of ~ 0.25 Msun, → dust temperature between 76 and 99 K, and the presence of large → dust grains of ~ 1 μm, as deduced from far-→ infrared excess. Assuming a normal → gas-to-dust ratio of 100, the total nebular mass of AG Car could be as high as ~ 30 Msun which would be of the order of, or even higher than, the mass of the → Homunculus nebula around → Eta Carinae. At the time when the AG Car nebula was ejected, the → interstellar bubble around the central star likely contained a negligible amount of material compared to the total mass of the nebula, implying that most of the nebular mass was ejected by the central star (Groh et al., 2009, ApJ 698, 1698).

See also: AG, as used in the → variable star designation system; → Carina.

A → Luminous Blue Variable star in the constellation → Carina; also known as HD 94910. AG Carinae lies about 6 kpc (20,000 → light-years) away and is surrounded by a → nebula. It is also a → spectroscopic variable, with the variability on time-scale of years. During the epochs of minimum in the visual → light curve (m_V ~ 8.1), the star is relatively hot and has a → WN11 spectral type, showing strong He I, H I, and N II → emission lines, weak He II 4686 Å emission, and Si IV 4088-4116 Å absorption. During the maximum epochs of the light curve (m_V ~ 6.0),
the star is cooler, and the spectrum is reminiscent of extreme A-type → hypergiants, with a strong emission of H I, Fe II, and T III lines. The transition between both phases is characterized by the appearance of peculiar features in the spectrum, such as absorption-line splitting, strong → electron-scattering wings in He I and Fe II lines, and apparent → inverse P Cygni profiles in He I lines.

The presence of a massive → bipolar nebula around AG Car testifies to a recent (t< 10⁴ years) phase of high → mass loss. The morphology and kinematics of the nebula suggest a → dynamical age of 8.5 × 10³ years and a high mass of → ionized nebular material (~ 4.2 Msun), which is likely composed of → ejecta from the central star. The nebular abundances show evidence of moderate nitrogen → enrichment. Properties of the → circumstellar nebula, studied in the → mid-infrared and → far-infrared, reveal an incredibly high dust mass of ~ 0.25 Msun, → dust temperature between 76 and 99 K, and the presence of large → dust grains of ~ 1 μm, as deduced from far-→ infrared excess. Assuming a normal → gas-to-dust ratio of 100, the total nebular mass of AG Car could be as high as ~ 30 Msun which would be of the order of, or even higher than, the mass of the → Homunculus nebula around → Eta Carinae. At the time when the AG Car nebula was ejected, the → interstellar bubble around the central star likely contained a negligible amount of material compared to the total mass of the nebula, implying that most of the nebular mass was ejected by the central star (Groh et al., 2009, ApJ 698, 1698).

See also: AG, as used in the → variable star designation system; → Carina.

Once more; a second time; in return.

Etymology (EN): M.E., from O.E. ongean “toward, opposite, against,” from on “on” + -gegn “against, toward.”

Etymology (PE): Dobâré, from do, → two, + bâr “time, fold,” → twice.

Once more; a second time; in return.

Etymology (EN): M.E., from O.E. ongean “toward, opposite, against,” from on “on” + -gegn “against, toward.”

Etymology (PE): Dobâré, from do, → two, + bâr “time, fold,” → twice.

In opposition to; contrary to; adverse or hostile to.

Etymology (EN): M.E. agens, ageynes, from ageyn, ongean “again,” from on + gegn “against, toward,” → gegenschein.

Etymology (PE): Patâr from Mid.Pers. paitiyârak, “every thing that counteracts and checks the good powers: adversaries of the evil powers;” Av. paiti-ār- “to advance against,” paiti-ārəna- “adversary,” from paiti- “against,” → counter-, + ar- “to move,” → access; cf.
Mod.Pers. patyâré “affliction, misery, misfortune; anything ugly, terrific;” Mid.Pers. padirag, patirak “against, counter-,” Sogd. patrêt “against, opposite, toward.”

In opposition to; contrary to; adverse or hostile to.

Etymology (EN): M.E. agens, ageynes, from ageyn, ongean “again,” from on + gegn “against, toward,” → gegenschein.

Etymology (PE): Patâr from Mid.Pers. paitiyârak, “every thing that counteracts and checks the good powers: adversaries of the evil powers;” Av. paiti-ār- “to advance against,” paiti-ārəna- “adversary,” from paiti- “against,” → counter-, + ar- “to move,” → access; cf.
Mod.Pers. patyâré “affliction, misery, misfortune; anything ugly, terrific;” Mid.Pers. padirag, patirak “against, counter-,” Sogd. patrêt “against, opposite, toward.”

In evolutionary models of → low-mass and → intermediate-mass stars, the occurrence of a → helium shell flash just at the moment when the star is leaving the → asymptotic giant branch phase.

See also: → AGB; → final; → thermal; → pulse.

In evolutionary models of → low-mass and → intermediate-mass stars, the occurrence of a → helium shell flash just at the moment when the star is leaving the → asymptotic giant branch phase.

See also: → AGB; → final; → thermal; → pulse.

1. The length of time that a celestial body or an evolutionary stage of it has existed, i.e. the age of a massive star, the age of a galaxy, a stellar cluster, and so on.
   
2. a: A period of time in the history of the Universe marked by a distinctive characteristic. → cosmic dark age. b: A division of geologic time in the history of the Earth, usually shorter than an epoch.

Etymology (EN): From O.Fr. aage, from Vulgar L. *ætaticum, from L. ætatem “period of life,” from ævum “lifetime, eternity, age;” cf. Mid.Pers. awâm, âwâm “time, season,” Av. âyav- “duration, period, time of life,” Skt. âyuh- “life, health”. All
from PIE *aiw-, *ayu- “vital force, life, long life, eternity.”

Etymology (PE): Senn from Ar. senn “age, lifetime”. Asr from Ar.

1. The length of time that a celestial body or an evolutionary stage of it has existed, i.e. the age of a massive star, the age of a galaxy, a stellar cluster, and so on.
   
2. a: A period of time in the history of the Universe marked by a distinctive characteristic. → cosmic dark age. b: A division of geologic time in the history of the Earth, usually shorter than an epoch.

Etymology (EN): From O.Fr. aage, from Vulgar L. *ætaticum, from L. ætatem “period of life,” from ævum “lifetime, eternity, age;” cf. Mid.Pers. awâm, âwâm “time, season,” Av. âyav- “duration, period, time of life,” Skt. âyuh- “life, health”. All
from PIE *aiw-, *ayu- “vital force, life, long life, eternity.”

Etymology (PE): Senn from Ar. senn “age, lifetime”. Asr from Ar.

Same as → Moon’s age.

See also: → Moon’s age.

Same as → Moon’s age.

See also: → Moon’s age.

The time elapsed since the → Big Bang.

See also: → age; → universe.

The time elapsed since the → Big Bang.

See also: → age; → universe.

Alternative name for the star Hadar,
the second brightest star in Centaurus and the tenth brightest star in the sky. → Hadar.

Etymology (EN): The etymology of Agena is not clear. Some sources have suggested L. a genu “by the knee,” but it seems dubious.

Alternative name for the star Hadar,
the second brightest star in Centaurus and the tenth brightest star in the sky. → Hadar.

Etymology (EN): The etymology of Agena is not clear. Some sources have suggested L. a genu “by the knee,” but it seems dubious.

1. Something such as a chemical substance, organism, or natural force that causes an effect.
   
2. Somebody who provides a particular service for another.

Etymology (EN): From L. agentem (nominative agens, genitive agentis), pr.p. of agere “to set in motion, drive, lead, conduct,” → act.

Etymology (PE): Konešgar, from koneš verbal noun of kardan “to do, to make” (Mid.Pers. kardan, O.Pers./Av. kar- “to do, make, build,” Av. kərənaoiti “makes,” cf. Skt. kr- “to do, to make,” krnoti “makes,”
karma “act, deed;” PIE base k^wer- “to do, to make”)

• -gar, → -or.

1. Something such as a chemical substance, organism, or natural force that causes an effect.
   
2. Somebody who provides a particular service for another.

Etymology (EN): From L. agentem (nominative agens, genitive agentis), pr.p. of agere “to set in motion, drive, lead, conduct,” → act.

Etymology (PE): Konešgar, from koneš verbal noun of kardan “to do, to make” (Mid.Pers. kardan, O.Pers./Av. kar- “to do, make, build,” Av. kərənaoiti “makes,” cf. Skt. kr- “to do, to make,” krnoti “makes,”
karma “act, deed;” PIE base k^wer- “to do, to make”)

• -gar, → -or.

Meteo.: The wind component deviating from the → geostrophic wind in the absence of the → geostrophic balance. In other words, ageostrophic wind is the difference between the true wind and the geostrophic wind.

See also: From negation prefix → a- + → geostrophic; → wind.

Meteo.: The wind component deviating from the → geostrophic wind in the absence of the → geostrophic balance. In other words, ageostrophic wind is the difference between the true wind and the geostrophic wind.

See also: From negation prefix → a- + → geostrophic; → wind.

1. (v.) To collect or gather into a cluster or mass.
   

2. (adj.) Gathered together into a cluster or mass.
   

3a) (n.) A mass of things clustered together.

3b) A rock composed of rounded or angular volcanic fragments (Dictionary.com).

Etymology (EN): From L. agglomeratus, p.p. of agglomerare “to wind or add onto a ball,” from → ad- “to” + glomerare to “wind up in a ball,” from glomus (genitive glomeris) “ball of yarn,” globus “globe;” PIE *gel- “to make into a ball.”

Etymology (PE): Bargolemidan, from suffix bar- “to, on, upon,” + golem, from Lori, Laki golemâ, golama “curd, obtained from milk by coagulation, used to make cheese,” Lori golem “stagnating water,” Sangesari, Semnâni, Sorxe-yi, Lâsgardi golma, “boll, i.e.
the rounded seed capsule of plants such as cotton,” + -idan infinitive suffix.

1. (v.) To collect or gather into a cluster or mass.
   

2. (adj.) Gathered together into a cluster or mass.
   

3a) (n.) A mass of things clustered together.

3b) A rock composed of rounded or angular volcanic fragments (Dictionary.com).

Etymology (EN): From L. agglomeratus, p.p. of agglomerare “to wind or add onto a ball,” from → ad- “to” + glomerare to “wind up in a ball,” from glomus (genitive glomeris) “ball of yarn,” globus “globe;” PIE *gel- “to make into a ball.”

Etymology (PE): Bargolemidan, from suffix bar- “to, on, upon,” + golem, from Lori, Laki golemâ, golama “curd, obtained from milk by coagulation, used to make cheese,” Lori golem “stagnating water,” Sangesari, Semnâni, Sorxe-yi, Lâsgardi golma, “boll, i.e.
the rounded seed capsule of plants such as cotton,” + -idan infinitive suffix.

1. A jumbled cluster or mass of varied parts.
   

2. The act or process of agglomerating (Dictionary.com).

See also: Verbal noun of → agglomerate.

1. A jumbled cluster or mass of varied parts.
   

2. The act or process of agglomerating (Dictionary.com).

See also: Verbal noun of → agglomerate.

The site where → Rosetta’s Philae lander is scheduled to touch down on Comet 67P/→ Churyumov-Gerasimenko on 12 November 2014.

See also: Named for Agilkia Island (اجیلکیا), an island on the Nile River in the south of Egypt. A complex of Ancient Egyptian buildings, including the famous Temple of Isis, was moved to Agilkia from the island of Philae when the latter was flooded during the building of the Aswan dams last century.

The site where → Rosetta’s Philae lander is scheduled to touch down on Comet 67P/→ Churyumov-Gerasimenko on 12 November 2014.

See also: Named for Agilkia Island (اجیلکیا), an island on the Nile River in the south of Egypt. A complex of Ancient Egyptian buildings, including the famous Temple of Isis, was moved to Agilkia from the island of Philae when the latter was flooded during the building of the Aswan dams last century.

1. To move or force into violent, irregular action. To shake or move briskly.
   

2. To disturb or excite emotionally; arouse; perturb.
   

3. To arouse or attempt to arouse public interest and support, as in some political or social cause or theory (Dictionary.com).

Etymology (EN): From L. agitatus, p.p. of agitare “move to and fro,” frequentative of agere “to drive,” → act.

Etymology (PE): Žilidan, from Lori, Laki žil “shaking, moving,”
related to žir, → act.

1. To move or force into violent, irregular action. To shake or move briskly.
   

2. To disturb or excite emotionally; arouse; perturb.
   

3. To arouse or attempt to arouse public interest and support, as in some political or social cause or theory (Dictionary.com).

Etymology (EN): From L. agitatus, p.p. of agitare “move to and fro,” frequentative of agere “to drive,” → act.

Etymology (PE): Žilidan, from Lori, Laki žil “shaking, moving,”
related to žir, → act.

The act or process of agitating; state of being agitated. → thermal agitation.

See also: Verbal noun of → agitate.

The act or process of agitating; state of being agitated. → thermal agitation.

See also: Verbal noun of → agitate.

1. A person who stirs up others in order to upset the status quo and further a political, social, or other cause.
   

2. A machine or device for agitating and mixing (Dictionary.com).

See also: → agitate; → -or; → turbulence.

1. A person who stirs up others in order to upset the status quo and further a political, social, or other cause.
   

2. A machine or device for agitating and mixing (Dictionary.com).

See also: → agitate; → -or; → turbulence.

1. To have the same views, emotions, etc.; harmonize in opinion or feeling (often followed by with).
   

2. To give consent; assent (often followed by to).
   

3. To come to one opinion or mind; come to an arrangement or understanding; arrive at a settlement.
   

4. To be consistent; harmonize (usually followed by with).
   

5. To correspond; conform; resemble (Dictionary.com).

Etymology (EN): M.E. agre, agreen, from O.Fr. agreer “to receive with favor, take pleasure in,” from phrase a gré “favorably, of good will,” from L. → ad- “to” + gratum “pleasing,” neuter of gratus
“pleasing, agreeable,” from PIE root *g^wer- “to praise;” cf. Pers. gerâmi “dear, revered,” from Av. gar- “to praise;” Skt. grnati “sings, praises,” Lith. giriu “to praise, celebrate.”

Etymology (PE): Infinitive from sâcan, → agreement.

1. To have the same views, emotions, etc.; harmonize in opinion or feeling (often followed by with).
   

2. To give consent; assent (often followed by to).
   

3. To come to one opinion or mind; come to an arrangement or understanding; arrive at a settlement.
   

4. To be consistent; harmonize (usually followed by with).
   

5. To correspond; conform; resemble (Dictionary.com).

Etymology (EN): M.E. agre, agreen, from O.Fr. agreer “to receive with favor, take pleasure in,” from phrase a gré “favorably, of good will,” from L. → ad- “to” + gratum “pleasing,” neuter of gratus
“pleasing, agreeable,” from PIE root *g^wer- “to praise;” cf. Pers. gerâmi “dear, revered,” from Av. gar- “to praise;” Skt. grnati “sings, praises,” Lith. giriu “to praise, celebrate.”

Etymology (PE): Infinitive from sâcan, → agreement.

1. The act of agreeing or of coming to a mutual arrangement.
   

2. The state of being in accord (Dictionary.com).

Etymology (EN): Verbal noun from → agree + → -ment.

Etymology (PE): Sâcan, from sâz-, saz, sac-, sâj-, Pers. sâz-, sâxtan “to build, prepare; to agree, be compatible; to adapt, adjust;” sazidan “to suit, fit, be worthy,” sazâ “suitable, agreeing with, congruous, deserving of;” Baluchi sâc-/sâcit “to adjust, be suitable, agree;” Mid.Pers. sacitan/sazidan “to fit,” sazešn “fitness,” sazâg “fitting, worth;” Av. sak- “to understand, to mark,” sâcaya- (causative) “to teach;”
Proto-Ir. *sac- “to fit, be suitable; to prepare;” + suffix -an, → minus.

1. The act of agreeing or of coming to a mutual arrangement.
   

2. The state of being in accord (Dictionary.com).

Etymology (EN): Verbal noun from → agree + → -ment.

Etymology (PE): Sâcan, from sâz-, saz, sac-, sâj-, Pers. sâz-, sâxtan “to build, prepare; to agree, be compatible; to adapt, adjust;” sazidan “to suit, fit, be worthy,” sazâ “suitable, agreeing with, congruous, deserving of;” Baluchi sâc-/sâcit “to adjust, be suitable, agree;” Mid.Pers. sacitan/sazidan “to fit,” sazešn “fitness,” sazâg “fitting, worth;” Av. sak- “to understand, to mark,” sâcaya- (causative) “to teach;”
Proto-Ir. *sac- “to fit, be suitable; to prepare;” + suffix -an, → minus.

The occupation or science of cultivating the land, producing crops, and feeding, breeding, and raising livestock; farming.

Etymology (EN): M.E., from M.Fr., from L. agricultura, compound of agri cultura “cultivation of land,” from agri, genitive of ager “a field”

• cultura “cultivation,” → culture.

Etymology (PE): Kešâvarzi “agriculture,” from kešâvarz “farmer, cultivator,” from kešt-varz. The first component kešt, variant kâšt, from kâštan, keštan, variants of kâridan “to cultivate, to plant;” Mid.Pers. kištan, kâridan “to sow, plant; to make furrows;” Av. kar- “to strew seed, cultivate,” kāraiieiti “cultivates;” cf. Skt. kar- “to scatter, strew, pour out.” The second component varz agent noun of
varzidan “to labor, exercise, practise;” cf. Gk. ergon “work;”
Arm. gorc “work;” Lith. verziu “tie, fasten, squeeze,” vargas “need, distress;” Goth. waurkjan; O.E. wyrcan “work,” wrecan “to drive, hunt, pursue;” PIE base *werg- “to do, to work.”

The occupation or science of cultivating the land, producing crops, and feeding, breeding, and raising livestock; farming.

Etymology (EN): M.E., from M.Fr., from L. agricultura, compound of agri cultura “cultivation of land,” from agri, genitive of ager “a field”

• cultura “cultivation,” → culture.

Etymology (PE): Kešâvarzi “agriculture,” from kešâvarz “farmer, cultivator,” from kešt-varz. The first component kešt, variant kâšt, from kâštan, keštan, variants of kâridan “to cultivate, to plant;” Mid.Pers. kištan, kâridan “to sow, plant; to make furrows;” Av. kar- “to strew seed, cultivate,” kāraiieiti “cultivates;” cf. Skt. kar- “to scatter, strew, pour out.” The second component varz agent noun of
varzidan “to labor, exercise, practise;” cf. Gk. ergon “work;”
Arm. gorc “work;” Lith. verziu “tie, fasten, squeeze,” vargas “need, distress;” Goth. waurkjan; O.E. wyrcan “work,” wrecan “to drive, hunt, pursue;” PIE base *werg- “to do, to work.”