Universe Guide

18 Sextantis

18 Sextantis Facts

  • 18 Sextantis is a giant star that can be located in the constellation of Sextans. The description is based on the spectral class.
  • 18 Sextantis is not part of the constellation outline but is within the borders of the constellation.
  • Based on the spectral type (K2III) of the star, the star's colour is orange to red .
  • The star can be seen with the naked eye, that is, you don't need a telescope/binoculars to see it.
  • The star is calculated at being about 473.39 light years away from us. Distance

18 Sextantis's Alternative Names

The Id of the star in the Yale Bright Star Catalogue is HR3996. HIP49865 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD88333.

Flamsteed designations are named after the creator, Sir John Flamsteed. Sir John named the stars in the constellation with a number and its latin name, this star's Flamsteed designation is 18 Sextantis. The Flamsteed name can be shortened to 18 Sex.

BD number is the number that the star was filed under in the Durchmusterung or Bonner Durchmusterung, a star catalogue that was put together by the Bonn Observatory between 1859 to 1903. The star's BD Number is BD-07 2977.

More details on objects' alternative names can be found at Star Names .

Location of 18 Sextantis

The location of the giant star in the night sky is determined by the Right Ascension (R.A.) and Declination (Dec.), these are equivalent to the Longitude and Latitude on the Earth. The Right Ascension is how far expressed in time (hh:mm:ss) the star is along the celestial equator. If the R.A. is positive then its eastwards. The Declination is how far north or south the object is compared to the celestial equator and is expressed in degrees. For 18 Sextantis, the location is 10h 10m 55.86 and -08° 25` 06.1 .

Radial Velocity and Proper Motion of 18 Sextantis

Proper Motion

All stars like planets orbit round a central spot, in the case of planets, its the central star such as the Sun. In the case of a star, its the galactic centre. The constellations that we see today will be different than they were 50,000 years ago or 50,000 years from now. Proper Motion details the movements of these stars and are measured in milliarcseconds. The star is moving -43.71 ± 0.26 milliarcseconds/year towards the north and -1.85 ± 0.38 milliarcseconds/year east if we saw them in the horizon.

Radial Velocity

The Radial Velocity, that is the speed at which the star is moving away/towards the Sun is 0.20000 km/s with an error of about 2.90 km/s . When the value is negative then the star and the Sun are getting closer to one another, likewise, a positive number means that two stars are moving away. Its nothing to fear as the stars are so far apart, they won't collide in our life-time, if ever.

Physical Properties of 18 Sextantis

18 Sextantis Colour and Temperature

Based on the star's spectral type of K2III , 18 Sextantis's colour and type is orange to red giant star. The star has a B-V Colour Index of 1.3 which means the star's temperature is about 4,322 Kelvin. The temperature was calculated using information from Morgans @ Uni.edu.

18 Sextantis Luminosity

Luminosity is the amount of energy that a star pumps out and its relative to the amount that our star, the Sun gives out. The figure of 198.24 that I have given is based on the value in the Simbad Hipparcos Extended Catalogue at the University of Strasbourg from 2012.

18 Sextantis Radius

18 Sextantis estimated radius has been calculated as being 18.01 times bigger than the Sun. The Sun's radius is 695,800km, therefore the star's radius is an estimated 12,531,988.11.km. If you need the diameter of the star, you just need to multiple the radius by 2. The figure is derived at by using the formula from SDSS rather than peer reviewed papers. It has been known to produce widely incorrect figures.

18 Sextantis Apparent and Absolute Magnitudes

18 Sextantis has an apparent magnitude of 5.64 which is how bright we see the star from Earth. Apparent Magnitude is also known as Visual Magnitude. Using the supplied Parallax value, you would get an absolute magnitude of -0.17 Magnitude, whether it be apparent/visual or absolute magnitude is measured by a number, the smaller the number, the brighter the Star is. Our own Sun is the brightest star and therefore has the lowest of all magnitudes, -26.74. A faint star will have a high number.

Distance to 18 Sextantis

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 6.89000 which gave the calculated distance to 18 Sextantis as 473.39 light years away from Earth or 145.14 parsecs. If you want that in miles, it is about 2,782,882,465,411,389.14, based on 1 Ly = 5,878,625,373,183.61 miles.

The star's Galacto-Centric Distance is 7,441.00 Parsecs or 24,269.81 Light Years. The Galacto-Centric Distance is the distance from the star to the Centre of the Galaxy which is Sagittarius A*.

Travel Time to 18 Sextantis

The time it will take to travel to this star is dependent on how fast you are going. U.G. has done some calculations as to how long it will take going at differing speeds. A note about the calculations, when I'm talking about years, I'm talking non-leap years only (365 days).

The New Horizons space probe is the fastest probe that we've sent into space at the time of writing. Its primary mission was to visit Pluto which at the time of launch (2006), Pluto was still a planet.

DescriptionSpeed (m.p.h.)Time (years)
Airbus A380736431,335,877.72
Speed of Sound (Mach 1)767.269413,757,373.23
Concorde (Mach 2)1,534.54206,878,416.99
New Horizons Probe33,0009,620,097.15
Speed of Light670,616,629.00473.39

Source of Information

The source of the information if it has a Hip I.D. is from Simbad, the Hipparcos data library based at the University at Strasbourg, France. Hipparcos was a E.S.A. satellite operation launched in 1989 for four years. The items in red are values that I've calculated so they could well be wrong. Information regarding Metallicity and/or Mass is from the E.U. Exoplanets. The information was obtained as of 12th Feb 2017.

Hide Explanations
Show GridLines

Additional 18 Sextantis Facts and Figures

Visual Facts

Primary / Proper / Traditional Name18 Sextantis
Alternative NamesHD 88333, HIP 49865, HR 3996, 18 Sex, BD-07 2977
Spectral TypeK2III
Constellation's Main StarNo
Multiple Star SystemNo / Unknown
Star TypeGiant Star
ColourOrange to Red
GalaxyMilky Way
Absolute Magnitude -0.17
Visual / Apparent Magnitude5.64
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)10h 10m 55.86
Declination (Dec.)-08° 25` 06.1
Galactic Latitude37.33076311 degrees
Galactic Longitude249.63118647 degrees
Distance from Earth6.89000 Parallax (milliarcseconds)
 473.39 Light Years
 145.14 Parsecs
 29,937,065.37 Astronomical Units
Galacto-Centric Distance24,269.81 Light Years / 7,441.00 Parsecs
Proper Motion Dec.-43.71000 ± 0.26000 milliarcseconds/year
Proper Motion RA.-1.85000 ± 0.38000 milliarcseconds/year
B-V Index1.3
Radial Velocity0.20000 ± 2.90 km/s
Semi-Major Axis7180.0000000
Stellar Luminosity (Lsun)198.2400000

Companions (Multi-Star and Exoplanets) Facts

Exoplanet CountNone/Unaware

Estimated Calculated Facts

Radius (x the Sun)18.01
Effective Temperature4,322 Kelvin

Sources and Links

SIMBAD SourceLink

Related Stars

Comments and Questions

There's no register feature and no need to give an email address if you don't need to. All messages will be reviewed before being displayed. Comments may be merged or altered slightly such as if an email address is given in the main body of the comment.

You can decline to give a name which if that is the case, the comment will be attributed to a random star. A name is preferred even if its a random made up one by yourself.

This website is using cookies. More info. That's Fine