Theta Aquilae
Template:Location mark Location of θ Aquilae (circled) | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Aquila[1] |
| Right ascension | Template:RA[2] |
| Declination | Template:DEC[2] |
| Apparent magnitude (V) | 3.26[3] |
| Characteristics | |
| Spectral type | B9.5 III + B9.5 III[4] |
| U−B Template:Engvar | Script error: No such module "val".[3] |
| B−V Template:Engvar | Script error: No such module "val".[3] |
| Variable type | Stable[5] |
| Astrometry | |
| Radial velocity (Rv) | Script error: No such module "val".[6] km/s |
| Proper motion (μ) | RA: +35.26 mas/yr[2] Dec.: +5.71 mas/yr[2] |
| Parallax (π) | 11.39±0.24 mas[2] |
| Distance | Template:Rnd ± Template:Rnd ly (Template:Rnd ± Template:Rnd pc) |
| Absolute magnitude (MV) | Script error: No such module "val"./+0.14[7] |
| Orbit[8] | |
| Period (P) | Script error: No such module "val". |
| Semi-major axis (a) | Script error: No such module "val".″ |
| Eccentricity (e) | 0.6040±0.0009 |
| Inclination (i) | 144.10±0.18° |
| Longitude of the node (Ω) | 96.92±0.19° |
| Periastron epoch (T) | Script error: No such module "val". |
| Argument of periastron (ω) (primary) | 33.73±0.22° |
| Semi-amplitude (K1) (primary) | 48.78±0.09 km/s |
| Semi-amplitude (K2) (secondary) | 63.48±0.11 km/s |
| Details | |
| θ Aql A | |
| Mass | Script error: No such module "val".[8] Template:Solar mass |
| Radius | Script error: No such module "val".[8] Template:Solar radius |
| Luminosity | Script error: No such module "val".[8] Template:Solar luminosity |
| Surface gravity (log g) | Script error: No such module "val".[8] cgs |
| Temperature | Script error: No such module "val".[8] K |
| Metallicity [Fe/H] | +0.20[9] dex |
| Rotational velocity (v sin i) | Script error: No such module "val".[8] km/s |
| Age | 215[8] Myr |
| θ Aql B | |
| Mass | Script error: No such module "val".[8] Template:Solar mass |
| Radius | Script error: No such module "val".[8] Template:Solar radius |
| Luminosity | Script error: No such module "val".[8] Template:Solar luminosity |
| Surface gravity (log g) | Script error: No such module "val".[8] cgs |
| Temperature | Script error: No such module "val".[8] K |
| Metallicity [Fe/H] | {{{metal_fe2}}} dex |
| Rotational velocity (v sin i) | Script error: No such module "val".[8] km/s |
| Other designations | |
| Template:Odlist[10] | |
| Database references | |
| SIMBAD | data |
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Theta Aquilae, also named Antinous,[11] is a binary star in the equatorial constellation Aquila. Its identifier is a Bayer designation that is Latinized from θ Aquilae, and abbreviated Theta Aql or θ Aql. The combined apparent visual magnitude of the pair is 3.26,[3] making it the fourth-brightest member of the constellation. This distance to this system can be determined through the parallax technique, yielding an estimate of roughly Script error: No such module "convert". from Earth.[2] It is drifting closer with a heliocentric radial velocity of −27 km/s.[6]
Properties
Theta Aquilae is a double-lined spectroscopic binary,[12] which indicates that the individual components have not been viewed through a telescope; instead, what can be observed is their combined spectrum with the individual absorption line features shifting back and forth over the course of an orbit because of the Doppler effect. Their orbit has a period of 17.1 days with a large orbital eccentricity is 0.60. At the estimated distance of this system, the angular separation of 3.2[7] milliarcseconds corresponds to a physical separation of about Script error: No such module "val"..[13]
A 2007 study classified both stars with a matching stellar classification of B9.5 III,[4] suggesting that they are massive, B-type giant stars that have exhausted the supply of hydrogen at their cores and evolved away from the main sequence of stars like the Sun. Hummel et al. (1996) gave the primary component, θ Aql A, an estimated mass of 3.6 solar, a radius 4.8 the Sun's, and 278 the luminosity of the Sun. For the secondary component, θ Aql B, they give the corresponding parameters as 2.9 times the mass, 2.4 times the radius and 68 times the luminosity of the Sun.[7]
Based upon their estimated parameters, Kaler (2008) suggests that θ Aql A is actually a subgiant star, while θ Aql B is a main sequence star.[13] Adelman et al (2015) confirm the main sequence status of the secondary component, and find that it is a weak Am star with overabundances of zirconium and barium.[5]
Etymology
In Chinese, Script error: No such module "Lang". (Script error: No such module "Lang".), meaning Celestial Drumstick, refers to an asterism consisting of θ Aquilae, 62 Aquilae, 58 Aquilae and η Aquilae.[14] Consequently, the Chinese name for θ Aquilae itself is Script error: No such module "Lang". (Script error: No such module "Lang"., Template:Langx.)[15] R. H. Allen's Star Names writes this name as Tseen Foo, applied specifically to θ Aquilae and translated as Heavenly Raft.[16] (See also τ Aquilae.)
In the catalogue of stars in the Calendarium of Al Achsasi al Mouakket, this star was designated Thanih Ras al Akab (تاني ألرأس ألعقاب - taanii al ra’s alʕuqāb), which was translated into Latin as Secunda Capitis Vulturis, meaning the second (star) of eagle's head.[17]
This star, along with δ Aql and η Aql, were Al Mizān (ألميزان), the Scale-beam.[16] According to the catalogue of stars in the Technical Memorandum 33-507 - A Reduced Star Catalog Containing 537 Named Stars, Al Mizān were the title for three stars :δ Aql as Al Mizān I, η Aql as Al Mizān II and θ Aql as Al Mizān III.[18]
This star, together with η Aql, δ Aql, ι Aql, κ Aql and λ Aql, constituted the obsolete constellation Antinous.[19] The IAU Working Group on Star Names approved the name Antinous for this star on 16 May 2024, after the obsolete constellation, and it is now so entered in the IAU Catalog of Star Names.[11]
References
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- ↑ a b c d e f g h i j k l m n Script error: No such module "citation/CS1".
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- ↑ Template:Cite simbad
- ↑ a b Script error: No such module "citation/CS1".
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- ↑ a b Script error: No such module "citation/CS1".
- ↑ Template:In lang 中國星座神話, written by 陳久金. Published by 台灣書房出版有限公司, 2005, Template:ISBN.
- ↑ Template:In lang AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 3 日 Template:Webarchive
- ↑ a b Script error: No such module "citation/CS1". Also available online here
- ↑ Script error: No such module "citation/CS1".
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- ↑ Script error: No such module "citation/CS1".
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