Theta2 Sagittarii

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Theta2 Sagittarii
Sagittarius IAU.svg
Red circle.svg
Location of θ2 Sagittarii (circled)
Observation data
Epoch J2000.0        Equinox J2000.0 (ICRS)
Constellation Sagittarius
Right ascension 19h 59m 51.35684s [1]
Declination −34° 41 52.0797 [1]
Apparent magnitude  (V)+5.30 [2]
Characteristics
Spectral type A4/A5 IV [3]
U−B color index +0.06 [2]
B−V color index +0.17 [2]
Astrometry
Radial velocity (Rv)−17.60 [4]  km/s
Proper motion (μ)RA: +108.23 [1]   mas/yr
Dec.: −69.51 [1]   mas/yr
Parallax (π)20.62 ± 0.28  mas [1]
Distance 158 ± 2  ly
(48.5 ± 0.7  pc)
Absolute magnitude  (MV)+1.87 [5]
Details
Mass 1.93 [6]   M
Luminosity 14 [7]   L
Surface gravity (log g)4.07±0.14 [6]   cgs
Temperature 8,113±276 [6]   K
Rotational velocity (v sin i)45.2±0.5 [8]  km/s
Age 809 [6]   Myr
Other designations
θ2 Sgr, CPD−35° 8701, HD  189118, HIP  98421, HR  7624, SAO  211717, WDS J19599-3442 [9]
Database references
SIMBAD data

Theta2 Sagittarii, Latinized from θ2 Sagittarii, is a solitary [10] star in the zodiac constellation of Sagittarius. It is faintly visible to the naked eye with an apparent visual magnitude of +5.30. [2] The star is progressing in the general direction of the Sun with a radial velocity of −17.60 km/s. [4] Based upon an annual parallax shift of 20.62  mas as seen from Earth, [1] it is located around 158  light years from the Sun. The star is drifting closer with a radial velocity of −17.6 km/s. [4]

The spectrum of Theta2 Sagittarii matches a stellar classification of A4/A5 IV, [3] indicating that, at the estimated age of 809 million years, [6] this is an evolving A-type subgiant star. It is a suspected Am star and may display photometric variability, at least during a 1992 observation period. [11] The star has an estimated 1.93 [6] times the mass of the Sun and is radiating 14 [7] times the Sun's luminosity from its photosphere at an effective temperature of 8,113 K. [6] It is spinning with a projected rotational velocity of 45.2 km/s. [8]

Theta2 Sagittarii has a pair of visual companions. Component B is a magnitude 11.3 star at an angular separation of 32.8  arc seconds along a position angle of 165°, as of 2000. Component C lies at an angular separation of 1.5 arc seconds along a position angle of 104° from component B, as of 1965. [12] Neither is physically associated with Theta2 Sagittarii itself. [10]

Related Research Articles

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Phi Sagittarii, Latinized from φ Sagittarii, is a star in the southern constellation of Sagittarius. With an apparent visual magnitude of 3.17, it is the ninth-brightest star in the constellation and is readily visible to the naked eye. Parallax measurements place it at a distance of roughly 239 light-years from the Earth. It is receding with a radial velocity of +21.5 km/s.

<span class="mw-page-title-main">Omicron Sagittarii</span> Star in the constellation Sagittarius

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Rho<sup>1</sup> Sagittarii Star in the constellation Sagittarius

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Beta<sup>2</sup> Sagittarii Star in the constellation Sagittarius

Beta² Sagittarii is a star in the zodiac constellation of Sagittarius. It is visible to the naked eye, having an apparent visual magnitude of +4.29. Based upon an annual parallax shift of 24.31 mas as seen from Earth, it is located 134 light-years from the Sun.

Chi<sup>1</sup> Sagittarii Star in the constellation Sagittarius

Chi1 Sagittarii (χ1 Sagittarii) is a binary star system in the zodiac constellation of Sagittarius. The pair have a combined apparent visual magnitude of +5.03, which is bright enough to be seen with the naked eye. Based upon an annual parallax shift of 12.95 mas as seen from Earth, it is located around 252 light years from the Sun. It is advancing through space in the general direction of the Earth with a radial velocity of −43.4 km/s.

Kappa<sup>1</sup> Sagittarii Star in the constellation Sagittarius

Kappa1 Sagittarii1 Sagittarii) is a solitary, white-hued star in the zodiac constellation of Sagittarius. It has an apparent visual magnitude of +5.58, which is bright enough to be faintly visible to the naked eye. According to the Bortle scale, it can be viewed from dark suburban skies. Based upon an annual parallax shift of 15.12 mas as seen from Earth, this star is located around 223 light years from the Sun. It is advancing in the general direction of the Sun with a radial velocity of −11.6 km/s.

Kappa<sup>2</sup> Sagittarii Star in the constellation Sagittarius

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<span class="mw-page-title-main">Nu Tauri</span> Star in the constellation Taurus

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<span class="mw-page-title-main">Tau Virginis</span> Star in the constellation Virgo

Tau Virginis is a single star in the zodiac constellation Virgo. With an apparent visual magnitude of 4.28, it is faintly visible to the naked eye. The distance to Tau Virginis, based upon parallax measurements, is approximately 225 light years with a margin of error of ±3 light years.

<span class="mw-page-title-main">Theta Volantis</span> A-type main sequence star in the constellation Volans

Theta Volantis, Latinized from θ Volantis, is a solitary star in the southern constellation of Volans. Based upon parallax measurements, is approximately 240 light years from the Sun. It has an apparent visual magnitude of 5.19, which is bright enough to be faintly visible to the naked eye.

Theta Geminorum is a single star in the northern zodiac constellation of Gemini. It is visual to the naked eye with an apparent visual magnitude of 3.59. Based upon an annual parallax shift of 17.25 mas, it is about 189 light years distant from the Sun.

HR 3082 is a double star in the northern circumpolar constellation of Camelopardalis. It is faintly visible to the naked eye with an apparent visual magnitude of 5.39. The system is moving closer to the Sun with a heliocentric radial velocity of +2.7 km/s. It is currently at a distance of around 323 light years, based upon an annual parallax shift of 10.10±0.24 mas.

<span class="mw-page-title-main">HR 6801</span> Star in the constellation Sagittarius

HR 6801 is a single star in the southern zodiac constellation of Sagittarius. It was designated as 1 Sagittarii by Flamsteed, but is now often referred to as 11 Sagittarii. Flamsteed's 11 Sgr actually refers to a different, much fainter star. The object is orange in hue and is visible to the naked eye as a faint point of light with an apparent visual magnitude of 4.96. The distance to this star is approximately 258 light years based on stellar parallax, and it is drifting further away with a radial velocity of +6 km/s.

<span class="mw-page-title-main">Theta Piscis Austrini</span> Star in the constellation Piscis Austrinus

Theta Piscis Austrini, Latinized as θ Piscis Austrini, is a binary star system in the southern constellation of Piscis Austrinus. It is faintly visible to the naked eye with a combined apparent visual magnitude of +5.01. Based upon an annual parallax shift of 10.16 mas as seen from the Earth, the system is located around 320 light years from the Sun. The system is drifting further away with a radial velocity of +13 km/s.

<span class="mw-page-title-main">34 Persei</span> Binary star system in the constellation Perseus

34 Persei is a binary star system in the northern constellation of Perseus. It is visible to the naked eye as a faint, blue-white hued point of light with a combined apparent visual magnitude of 4.67. The system is located approximately 540 light years away from the Sun based on parallax, but it is drifting closer with a radial velocity of −3.5 km/s. It is a likely member of the Alpha Persei Cluster.

<span class="mw-page-title-main">52 Sagittarii</span> Binary star system in the constellation Sagittarius

52 Sagittarii is a binary star system in the southern constellation of Sagittarius. It has the Bayer designation h2 Sagittarii, while 52 Sagittarii is the Flamsteed designation. This system is visible to the naked eye as a faint, blue-white hued point of light with an apparent visual magnitude of 4.59. It is located approximately 190 light years away based on parallax, but is drifting closer with a radial velocity of −19 km/s.

<span class="mw-page-title-main">21 Sagittarii</span> Binary star system in the constellation Sagittarius

21 Sagittarii is a binary star system in the southern zodiac constellation of Sagittarius. It is visible to the naked eye as a faint point of light with a combined apparent visual magnitude of 4.81. The system is located approximately 410 light years away from the Sun based on parallax. It is moving closer to the Earth with a heliocentric radial velocity of −11.80 km/s.

<span class="mw-page-title-main">V4199 Sagittarii</span> Star in the constellation Sagittarius

V4199 Sagittarii is a variable star in the southern constellation of Sagittarius. It is a dim star that is just visible to the naked eye with an apparent visual magnitude that varies between 6.22 and 6.28 over a period of 1.23825 days. The star is located at a distance of approximately 689 light years from the Sun based on parallax, but is drifting closer with a radial velocity of roughly −23 km/s. It has an absolute magnitude of −0.63, on average.

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