FredericBernard: Created page with "{{Night Sky | image = | designation =σ Octantis
Polaris Australis | rightascension =21^h 08^m 46.8434^s[http..."

2019-03-19T16:09:07Z

Created page with "{{Night Sky | image = | designation =σ Octantis Polaris Australis | rightascension =21h 08m 46.8434s<ref name=simbad>[http..."

New page

{{Night Sky
| image =
| designation =σ Octantis Polaris Australis
| rightascension =21h 08m 46.8434s<ref name=simbad>[https://simbad.u-strasbg.fr/simbad/sim-id?Ident=sigma+octantis&submit=submit+id Sigma Octantis] from the [http://simbad.u-strasbg.fr/simbad SIMBAD Astronomical Database]</ref>
| declination =-88° 57′ 23.4117″<ref name=simbad/>
| distance =270 ly<ref name=constellation-guide>{{cite web|url=https://www.constellation-guide.com/constellation-list/octans-constellation/|title=Octans Constellation|accessdate=2019-03-19}}</ref>
| constellation =Octans
| type =Star
| dimensions =
| magnitude =Apparent Mag: +5.42<ref name=simbad/> Absolute Mag: +0.77<ref name=universeguide>{{cite web|url=https://www.universeguide.com/star/polarisaustralis|title=Polaris Australis, Sigma Octantis, HD177482, HIP104382, HR7228|accessdate=2019-03-19}}</ref>
| redshift =
| radvelocity =11.9±2 km/s<ref name=simbad/>
| propmotion =RA: 26.67 mas/yr<ref name=simbad/> Dec.: 5.61 mas/yr<ref name=simbad/>
| parallax =11.09±0.14 mas<ref name=simbad/>
}}
'''Sigma Octantis''' (σ Octantis, Polaris Australis) is the closest bright [[star]] to the South celestial pole.<ref name=constellation-guide/> It is the counterpart to [[Polaris]] in the Northern hemisphere, though Sigma Octantis is 25 times fainter than Polaris making it too dim to be useful for navigational purposes. Located in the Southern [[constellation]] of [[Octans]], it is in fact a [[variable star|Delta Scuti variable star]].<ref name=astro>{{cite web|url=http://stars.astro.illinois.edu/sow/polaust.html|title=Sigma Octantis|accessdate=2019-03-19}}</ref> This variability is caused by radial and non-radial pulsations of the star's surface. The star's brightness varies only slightly by 0.03 magnitudes over the course of its period of 2.3 hours.<ref name=constellation-guide/>

The star is a yellow-white giant star with spectral class F0III.<ref name=constellation-guide/> Sigma Octantis has a mass of 2 [[solar mass]]es, twice that of the [[Sun]] with a [[radius]] 3.7 times greater.<ref name=astro/> The star rotates about its axis with a period of 1.5 days, meaning a point on its equator moves at around 128 km/s.<ref name=astro/> The [[metallicity]] of the star is also high, about 1.8 times more than the Sun. It is situated around 1 degree from the South celestial pole. The star is also a little hotter than the Sun at 7,322 [[kelvin]].<ref name=universeguide/>

The name "Sigma Octantis" was assigned to the star by [[John Bayer]] in 1603.<ref name=universeguide/> It can just about be observed with the unaided eye.

==References==
{{reflist}}

{{Stars}}

[[Category:Astronomy]]
[[Category:Stars]]

Sigma Octantis - Revision history

FredericBernard: Created page with "{{Night Sky | image = | designation =σ OctantisPolaris Australis | rightascension =21h 08m 46.8434s[http..."

FredericBernard: Created page with "{{Night Sky | image = | designation =σ Octantis
Polaris Australis | rightascension =21^h 08^m 46.8434^s[http..."