Universe Guide

FO Serpentis (Carbon Star) Facts

FO Serpentis Facts

  • FO Serpentis is a pulsating Carbon star that can be located in the constellation of Serpens. The description is based on the spectral class.
  • FO Serpentis is not part of the constellation outline but is within the borders of the constellation.
  • Based on the spectral type (C) of the star, the star's colour is carbon red .
  • The star can not be seen by the naked eye, you need a telescope to see it.
  • Using the most recent figures given by the 2007 Hipparcos data, the star is 2265.02 light years away from us. Distance

FO Serpentis's Alternative Names

HIP89783 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD168227.

FO Serpentis has alternative name(s) :- , FO Ser.

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-15 4923.

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

Location of FO Serpentis

The location of the Carbon 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 FO Serpentis, the location is 18h 19m 21.81 and -15° 36` 46.1 .

Radial Velocity and Proper Motion of FO Serpentis

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 -0.68 ± 0.52 milliarcseconds/year towards the north and 0.41 ± 0.96 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 -16.20000 km/s with an error of about 3.50 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 FO Serpentis

FO Serpentis Colour and Temperature

Based on the star's spectral type of C , FO Serpentis's colour and type is carbon red Carbon star. The star has a B-V Colour Index of 1.84 which means the star's temperature is about 2,817 Kelvin. The temperature was calculated using information from Morgans @ Uni.edu.

FO Serpentis Radius

FO Serpentis estimated radius has been calculated as being 29.47 times bigger than the Sun. The Sun's radius is 695,800km, therefore the star's radius is an estimated 20,502,558.01.km. If you need the diameter of the star, you just need to multiple the radius by 2. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 56.148397977530060673028193064. 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.

FO Serpentis Apparent and Absolute Magnitudes

FO Serpentis has an apparent magnitude of 8.43 which is how bright we see the star from Earth. Apparent Magnitude is also known as Visual Magnitude. If you used the 1997 Parallax value, you would get an absolute magnitude of 0.62 If you used the 2007 Parallax value, you would get an absolute magnitude of -0.78. 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 FO Serpentis

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 2.74000 which gave the calculated distance to FO Serpentis as 1190.38 light years away from Earth or 364.96 parsecs. If you want that in miles, it is about 6,997,798,071,730,305.67, based on 1 Ly = 5,878,625,373,183.61 miles.

In 2007, Hipparcos data was revised with a new parallax of 1.44000 which put FO Serpentis at a distance of 2265.02 light years or 694.44 parsecs. It should not be taken as though the star is moving closer or further away from us. It is purely that the distance was recalculated.

Using the 2007 distance, the star is roughly 143,237,533.96 Astronomical Units from the Earth/Sun give or take a few. An Astronomical Unit is the distance between Earth and the Sun. The number of A.U. is the number of times that the star is from the Earth compared to the Sun.

Travel Time to FO Serpentis

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 A3807362,063,804,452.47
Speed of Sound (Mach 1)767.2691,979,696,921.18
Concorde (Mach 2)1,534.54989,847,170.50
New Horizons Probe33,00046,029,093.24
Speed of Light670,616,629.002,265.02

Variable Type of FO Serpentis

The star is a pulsating Slow Irregular variable type which means that its size changes over time. The Variable Type is usually named after the first star of that type to be spotted. FO Serpentis brightness ranges from a magnitude of 8.608 to a magnitude of 8.426 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 0.1 days (variability).

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.

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Additional FO Serpentis Facts and Figures

Visual Facts

Primary / Proper / Traditional NameFO Serpentis
Alternative NamesHD 168227, HIP 89783, BD-15 4923, FO Ser
Spectral TypeC
Constellation's Main StarNo
Multiple Star SystemNo / Unknown
Star TypeCarbon Star
GalaxyMilky Way
Absolute Magnitude 0.62 / -0.78
Visual / Apparent Magnitude8.43
Naked Eye VisibleRequires a 7x50 Binoculars - Magnitudes
Right Ascension (R.A.)18h 19m 21.81
Declination (Dec.)-15° 36` 46.1
Galactic Latitude-0.18068701 degrees
Galactic Longitude15.42694868 degrees
1997 Distance from Earth2.74000 Parallax (milliarcseconds)
 1190.38 Light Years
 364.96 Parsecs
2007 Distance from Earth1.44000 Parallax (milliarcseconds)
 2265.02 Light Years
 694.44 Parsecs
 143,237,533.96 Astronomical Units
Proper Motion Dec.-0.68000 ± 0.52000 milliarcseconds/year
Proper Motion RA.0.41000 ± 0.96000 milliarcseconds/year
B-V Index1.84
Radial Velocity-16.20000 ± 3.50 km/s

Companions (Multi-Star and Exoplanets) Facts

Exoplanet CountNone/Unaware

Variable Star Details

Variable Star ClassPulsating
Variable Star TypeSlow Irregular
Mean Variability Period in Days0.149
Variable Magnitude Range (Brighter - Dimmer)8.426 - 8.608

Estimated Calculated Facts

Radius (x the Sun)56.15
Effective Temperature2,817 Kelvin

Sources and Links

SIMBAD SourceLink

Related Stars

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