V718 Coronae Australis

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V718 Coronae Australis
Corona Australis constellation map.svg
Red circle.svg
Location of V718 CrA (circled)
Observation data
Epoch J2000.0        Equinox J2000.0 (ICRS)
Constellation Corona Australis
Right ascension 18h 39m 35.15900s [1]
Declination −43° 11′ 09.1691″ [1]
Apparent magnitude  (V)5.43±0.01 [2]
Characteristics
Evolutionary stage AGB [3]
Spectral type M2 III [4]
B−V color index +1.63 [5]
Variable type LB: [6]
Astrometry
Radial velocity (Rv)28.5±0.8 [7]  km/s
Proper motion (μ)RA: −32.414  mas/yr [1]
Dec.: −43.168  mas/yr [1]
Parallax (π)5.1919 ± 0.0901  mas [1]
Distance 630 ± 10  ly
(193 ± 3  pc)
Absolute magnitude  (MV)−1.03 [8]
Details
Mass 1.45 [9] or 2 [10]   M☉
Radius 101±5 [11]   R☉
Luminosity 1,001 [12]   L☉
Temperature 3,698±122 [13]   K
Other designations
18 G. Coronae Australis [14] , V718 CrA, CD−43°12699, CPD−43°8703, GC  25488, HD  171697, HIP  91494, HR  6991, SAO  229172 [15]
Database references
SIMBAD data

V718 Coronae Australis (HD 171697; HR 6991; V718 CrA) is a solitary variable star [16] located in the southern constellation Corona Australis. It is faintly visible to the naked eye as a red-hued point of light with an apparent magnitude of 5.43. [2] Gaia DR3 parallax measurements imply a distance of 630 light years [1] and it is currently receding with a heliocentric radial velocity of 28.5  km/s . [7] At its current distance V718 CrA's brightness is diminished by 0.37 magnitudes due to interstellar dust [17] and it has an absolute magnitude of −1.03. [8]

A light curve for V718 Coronae Australis, plotted from Hipparcos data V718CrALightCurve.png
A light curve for V718 Coronae Australis, plotted from Hipparcos data

This object was first noticed to be potentially variable by Olin J. Eggen in 1973. [19] Its variability was confirmed in 1999 after subsequent observations and was given the variable star designation V718 Coronae Australis. [20] Observations from Koen & Laney (2000) reveal that V718 CrA has two periods: one lasting 5.37 days and the other lasting 71.1 days. [10] It is a slow irregular variable of subtype Lb that fluctuates between 5.45 and 5.51 in the Hipparcos passband. [6]

V718 CrA has a stellar classification of M2 III, indicating that it is an evolved red giant. It is currently on the asymptotic giant branch, [3] fusing hydrogen and helium shells around an inert carbon core. It has 1.45 times the mass of the Sun [9] but it has expanded to 101 times the Sun's radius. [11] It radiates 1,001 times the luminosity of the Sun [12] from its enlarged photosphere at an effective temperature of 3,698  K . [13] Oscillation measurements from Koen & Laney (2000) yield a mass of 2  M☉. [10]

Related Research Articles

<span class="mw-page-title-main">Beta Coronae Australis</span> Star in the constellation Corona Australis

Beta Coronae Australis, Latinized from β Coronae Australis, is a solitary star located in the southern constellation Corona Australis. It is visible to the naked eye as a faint, orange-hued star with an apparent visual magnitude of 4.10. The star is located around 470 light years distant from the Sun based on parallax, and is drifting further away with a radial velocity of 2.7 km/s. At its current distance, Beta CrA's brightness is diminished by 0.29 magnitudes due to interstellar dust.

<span class="mw-page-title-main">CQ Camelopardalis</span> Star in the constellation Camelopardalis

CQ Camelopardalis, abbreviated as CQ Cam, is a solitary variable star in the northern circumpolar constellation Camelopardalis. It has an apparent magnitude of 5.19, making it visible to the naked eye under ideal conditions. The object is relatively far at a distance of about 2,000 light years but is drifting closer with a heliocentric radial velocity of −22 km/s. It has a peculiar velocity of 21.8+2.1
−1.9 km/s, making it a runaway star.

<span class="mw-page-title-main">HD 27245</span> Star in the constellation Camelopardalis

HD 27245, also known as HR 1335 or rarely 25 H. Camelopardalis is a solitary red-hued star located in the northern circumpolar constellation Camelopardalis. It has an apparent magnitude of 5.4, making it faintly visible to the naked eye. Gaia DR3 Parallax measurements place it approximately 607 light years away from it the Solar System and is drifting further away with a heliocentric radial velocity of 25.2 km/s. At its current distance, HD 27245's brightness is diminished by 0.36 magnitudes due to extinction from interstellar dust. It has an absolute magnitude of −0.27.

Eta<sup>2</sup> Coronae Australis Star in the constellation Corona Austrlis

Eta2 Coronae Australis, Latinized from η2 Coronae Australis, is a solitary star located in the southern constellation of Corona Australis. It is visible to the naked eye as a dim, blue-white hued star with an apparent visual magnitude of 5.59. Gaia DR3 parallax measurements imply a distance of 770 light years from the Solar System, but it is drifting closer with a radial velocity of −23 km/s. At its current distance Eta2 CrA's brightness is diminished by 0.27 magnitudes due to stellar extinction from interstellar dust and it has an absolute magnitude of −0.24.

<span class="mw-page-title-main">Mu Coronae Australis</span> Star in the constellation Corona Australis

Mu Coronae Australis, Latinized from μ Coronae Australis, is a solitary yellow-hued star located in the southern constellation Corona Australis. It has an apparent magnitude of 5.22, making it faintly visible to the naked eye. Gaia DR3 parallax measurements put it 386 light years away and is currently approaching the Solar System with a heliocentric radial velocity of −18.2 km/s. At its current distance, Mu CrA's brightness is diminished by 0.31 magnitudes due to interstellar dust. It has an absolute magnitude of −0.22.

Kappa<sup>2</sup> Coronae Australis Star in the constellation Corona Australis

Kappa2 Coronae Australis, Latinized from κ2 Coronae Australis, is the primary of a probable binary system located in the southern constellation Corona Australis. It is visible to the naked eye as a bluish-white hued star with an apparent visual magnitude of 5.59. The distance to this star is roughly 710 light years based on Gaia DR3 parallax measurements. The radial velocity is poorly constrained, but the star appears to be moving closer with a radial velocity of around −15 km/s. At its current distance, Kappa2 CrA's brightness is diminished by 0.45 magnitudes due to interstellar dust.

<span class="mw-page-title-main">S Apodis</span> Variable star in the constellation Apus

S Apodis, also known as HD 133444 is a variable star located in the southern circumpolar constellation Apus. It has an apparent magnitude ranging from 9.6 to 17, which is below the limit for naked eye visibility. The object is located relatively far at a distance of approximately 15,000 light years based on Gaia DR3 parallax measurements, but it is drifting closer with a heliocentric radial velocity of −75 km/s.

<span class="mw-page-title-main">HD 57197</span> Star in the constellation Puppis

HD 57197, also known as M Puppis or HR 2789, is a suspected astrometric binary located in the southern constellation Puppis, the poop deck. It has an apparent magnitude of 5.84, making it faintly visible to the naked eye under ideal conditions. Based on parallax measurements from the Gaia satellite, the system is estimated to be 629 light years away from the Solar System. The value is poorly constrained, but it appears to be receding with a heliocentric radial velocity of 13 km/s. At its current distance, HD 57197's brightness is diminished by 0.3 magnitudes due to interstellar dust. It has an absolute magnitude of -0.43.

Pi<sup>2</sup> Octantis Star in the constellation Octans

Pi2 Octantis, Latinized from π2 Octantis, is a solitary star situated in the southern circumpolar constellation Octans. It has an apparent magnitude of 5.64, allowing it to be faintly visible to the naked eye under ideal conditions. Located 1,570 light years away, the star is approaching the Sun with a heliocentric radial velocity of −13.8 km/s.

HD 1032 is a solitary star in the southern circumpolar constellation Octans. It is faintly visible to the naked eye with an apparent magnitude of 5.77 and is estimated to be 850 light years away from the Solar System based on parallax measure. However, it is receding with a heliocentric radial velocity of 4 km/s.

<span class="mw-page-title-main">WZ Columbae</span> Star in the constellation of Columba

WZ Columbae, also known as HD 38170, is a solitary, bluish-white hued star located in the southern constellation Columba, the dove. It has an apparent magnitude of 5.28, allowing it to be faintly visible to the naked eye. Based on parallax measurements from the Gaia spacecraft, the object is about 365 light years distant. It appears to be receding from the Solar System, having a heliocentric radial velocity of 36.3 km/s.

<span class="mw-page-title-main">AF Columbae</span> Star in the constellation of Columba

AF Columbae, also known as HD 42682, is a solitary, red hued variable star located in the southern constellation Columba, the dove. It has an apparent magnitude that fluctuates between 5.6 and 5.71. Nevertheless, it is faintly visible to the naked eye. Parallax measurements from the Gaia spacecraft place the star relatively far at a distance of 820 light years. However, it is approaching the Solar System with a poorly constrained radial velocity of −19 km/s.

HD 34255, also known HR 1720, is a star located in the northern circumpolar constellation Camelopardalis, the giraffe. It has an apparent magnitude of 5.60, allowing it to be faintly visible to the naked eye. The object is located relatively far at a distance of about 1.65 kly but is approaching the Solar System with a heliocentric radial velocity of −7.7 km/s.

<span class="mw-page-title-main">HD 40091</span> Star in the constellation Columba

HD 40091, also known as HR 2082, is a solitary star located in the southern constellation Columba, the dove. It has an apparent magnitude of 5.54, making it faintly visible to the naked eye under ideal conditions. Based on parallax measurements from the Gaia spacecraft, the object is estimated to be 501 light years distant. However, it is rapidly receding with a high heliocentric radial velocity of 114 km/s.

<span class="mw-page-title-main">8 Leonis Minoris</span> Star in the constellation of Leo Minor

8 Leonis Minoris is a solitary, red hued star located in the northern constellation Leo Minor. It has an apparent magnitude 5.37, making it faintly visible to the naked eye. Based on parallax measurements from the Gaia satellite, the object is estimated to be 492 light years distant. It is receding with a heliocentric radial velocity of 40 km/s. At its current distance, 8 LMi is diminshed by 0.12 magnitudes due to interstellar dust.

<span class="mw-page-title-main">HD 197630</span> Star in the constellation of Microscopium

HD 197630, also known as HR 7933 or rarely 23 G. Microscopii, is a probable astrometric binary located in the southern constellation Microscopium. The visible component is a bluish-white hued star that is faintly visible to the naked eye with an apparent magnitude of 5.47. Based on parallax measurements from the Gaia satellite, the system is estimated to be 328 light years away. However, it is drifting closer with a heliocentric radial velocity of −30 km/s. At its current distance, HD 197630's brightness is diminished by 0.11 magnitudes due to interstellar dust. A 2012 multiplicity survey failed to confirm the velocity variations.

<span class="mw-page-title-main">HD 175219</span> K-type giant; Corona Australis

HD 175219, also known as HR 7122, is a solitary, orange hued star located in the southern constellation Corona Australis. It has an apparent magnitude of 5.35, allowing it to be faintly visible to the naked eye. The object is located relatively close at a distance of 314 light years based on Gaia DR3 parallax measurements but is drifting closer with a heliocentric radial velocity of −21.1 km/s. At its current distance, HD 175219's brightness is diminished by 0.26 magnitudes due to interstellar dust. It has an absolute magnitude of +0.57.

<span class="mw-page-title-main">HD 170642</span> A-type dwarf; Corona Australis

HD 170642, also designated as HR 6942 or rarely 13 G. Coronae Australis, is a single star located in the southern constellation Corona Australis. It is faintly visible to the naked eye as a white hued star with an apparent magnitude of 5.16. The object is located relatively close at a distance of 229 light years based on Hipparcos parallax measurements, but it is approaching the Solar System with a somewhat constrained heliocentric radial velocity of −6 km/s. At its current distance, HD 170642's brightness is diminished by 0.28 magnitudes due to interstellar dust. It has an absolute magnitude of +0.93.

<span class="mw-page-title-main">V686 Coronae Australis</span> Alpha2 CVn variable; Corona Australis

V686 Coronae Australis is a solitary, bluish-white-hued variable star located in the southern constellation Corona Australis. It has an apparent magnitude that ranges between 5.25 and 5.41, which makes it faintly visible to the naked eye. Gaia DR3 parallax measurements imply a distance of 480 light years and it is slowly receding with a heliocentric radial velocity of 1.3 km/s. At its current distance V686 CrA's average brightness is diminished by 0.35 magnitudes due to extinction from interstellar dust and it has an absolute visual magnitude of −0.24.

<span class="mw-page-title-main">HD 170521</span> Distant K-type giant; Corona Australis

HD 170521, also known as HR 6937 or rarely 12 G. Coronae Australis, is a solitary star located in the southern constellation Corona Australis. It is faintly visible to the naked eye as an orange-hued point of light with an apparent magnitude of 5.69. The object is located relatively far at a distance of approximately 1,500 light years based on Gaia DR3 parallax measurements, and it is receding with a heliocentric radial velocity of 7.2 km/s. At its current distance, HD 170521's brightness is heavily diminished by 0.46 magnitudes due to extinction from interstellar dust and it has an absolute magnitude of −1.90.

References

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