Sigma Octantis

Octans and around, with Sigma Octantis in the middle marked in cyan.
Observation data Epoch J2000
Constellation	Octans
Right ascension	21h 08m 46.8s
Declination	-88° 57′ 23″
Apparent magnitude (V)	5.42
Characteristics
Spectral type	F0 III
B-V color index	0.27
U-B color index	0.13
Variable type	Delta Scuti
Astrometry
Radial velocity (Rv)	+11.9 km/s
Proper motion (μ)	RA: 25.96 mas/yr Dec.: 5.02 mas/yr
Parallax (π)	12.07 ± 0.48 mas
Distance	270 ly (83 pc)
Absolute magnitude (MV)	0.83
Other designations
Polaris Australis, HR 7228, HD 177482, SAO 258857, FK5 923, HIP 104382.
Database references
SIMBAD	data

Sigma Octantis (σ Oct / σ Octantis) is a magnitude 5.5 star in the constellation Octans. Image File history File links Octans_01. ... In astronomy, an epoch is a moment in time for which celestial coordinates or orbital elements are specified. ... This article or section does not cite its references or sources. ... Octans (Latin for octant) is an inconspicuous constellation introduced by Nicolas Louis de Lacaille. ... Right ascension (RA; symbol α: Greek letter alpha) is the astronomical term for one of the two coordinates of a point on the celestial sphere when using the equatorial coordinate system. ... In astronomy, declination (dec) is one of the two coordinates of the equatorial coordinate system, the other being either right ascension or hour angle. ... // Headline text HEY!! HOW ARE YOU ALL?? Its nice of you to come read this page. ... In astronomy, stellar classification is a classification of stars based initially on photospheric temperature and its associated spectral characteristics, and subsequently refined in terms of other characteristics. ... In astronomy, color index is a simple numerical expression that determines the color of an object, which in the case of a star gives its temperature. ... In astronomy, color index is a simple numerical expression that determines the color of an object, which in the case of a star gives its temperature. ... Most stars are of almost constant luminosity. ... A Delta Scuti variable is a variable star which exhibits variations in its luminosity due to both radial and non-radial pulsations of the stars surface. ... This article does not cite its references or sources. ... Radial velocity is the velocity of an object in the direction of the line of sight. ... kilometre per second is an SI derived unit of both speed (scalar) and velocity (vector), signified by the symbol km/s or km s-1. ... The proper motion of a star is the motion of the position of the star in the sky (the change in direction in which we see it, as opposed to the radial velocity) after eliminating the improper motions of the stars, which affect their measured coordinates but are not real... A milliarcsecond (m, mas) , or a thoundsanth of an arcsecond. ... A year is the time between two recurrences of an event related to the orbit of the Earth around the Sun. ... A milliarcsecond (m, mas) , or a thoundsanth of an arcsecond. ... A year is the time between two recurrences of an event related to the orbit of the Earth around the Sun. ... This article or section does not cite its references or sources. ... A milliarcsecond (m, mas) , or a thoundsanth of an arcsecond. ... Distance is a numerical description of how far apart things lie. ... A light year, abbreviated ly, is the distance light travels in one year: roughly 9. ... Stellar parallax motion The parsec (symbol pc) is a unit of length used in astronomy. ... In astronomy, absolute magnitude is the apparent magnitude, m, an object would have if it were at a standard luminosity distance away from us (in the absence of interstellar extinction!). It allows the overall brightnesses of objects to be compared without regard to distance. ... In astronomy, many stars are referred to simply by catalogue numbers. ... In astronomy, many stars are referred to simply by catalogue numbers. ... The Henry Draper Catalogue is an astronomy catalogue with astrometric and spectroscopic data about more than 225,000 stars. ... The Smithsonian Astrophysical Observatory (SAO) is a research institute of the Smithsonian Institution headquartered in Cambridge, Massachusetts, where it is joined with the Harvard College Observatory (HCO) to form the Harvard-Smithsonian Center for Astrophysics (CfA). ... Fifth Fundamental Catalogue is a glossary of positions of stars. ... In astronomy, many stars are referred to simply by catalogue numbers. ... SIMBAD (the Set of Identifications, Measurements, and Bibliography for Astronomical Data) is a database of astronomical information about objects within the Milky Way. ... // Headline text HEY!! HOW ARE YOU ALL?? Its nice of you to come read this page. ... Octans (Latin for octant) is an inconspicuous constellation introduced by Nicolas Louis de Lacaille. ...

Its position near the southern celestial pole makes it the southern hemisphere's pole star and counterpart to Polaris, the current North Star. To an observer in the southern hemisphere, Sigma Octantis appears almost motionless and all the other stars in the Southern sky appear to rotate around it. It is part of a small "half hexagon" shape. It is over a degree away from the true south pole, and the south pole is moving away from it due to precession of the equinoxes. The Southern Hemisphere is the half of a planets surface (or celestial sphere) that is south of the equator (the word hemisphere literally means half ball). On Earth it contains five continents (Antarctica, Australia, most of South America, parts of Africa and Asia) as well as four oceans (South... For other uses of the words Pole star and Polestar see Polestar (disambiguation). ... Polaris (α UMi / α Ursae Minoris / Alpha Ursae Minoris) is the brightest star in the constellation Ursa Minor. ... The North Star is a title of the star best suited for navigation northwards. ... Precession of the equinoxes refers to the precession of the Earths axis of rotation. ...

Sigma Octantis is sometimes called Polaris Australis, or South Star. However, it is a faint star—at magnitude 5.5 it is barely visible to the naked eye—which makes it a rather poor pole star, especially by comparison with the much brighter and easily visible Polaris. The South Star is the star which is circumpolar to the celestial South Pole (as Polaris, the North Star, is for the celestial North Pole), and can thus be reliably used for navigation. ... Polaris (α UMi / α Ursae Minoris / Alpha Ursae Minoris) is the brightest star in the constellation Ursa Minor. ...

Sigma Octantis is the dimmest star to be represented on a national flag. It appears on the flag of Brazil, symbolising the capital city Brasilia. National flag and ensign. ... Bras lia is the capital city of Brazil and is located in the center of the country in a federal district created in the state of Goi s. ...

References

• HD 177482 -- Variable Star. SIMBAD Astronomical Database. Retrieved on 2005-11-05.