Universe Guide


V399 Lacertae, HD210221, HIP109205

V399 Lacertae is a blue very luminous supergiant star that can be located in the constellation of Lacerta. V399 Lacertae is the brightest star in Lacerta based on the Hipparcos 2007 apparent magnitude. The star can be seen with the naked eye, that is, you don't need a telescope/binoculars to see it.

HIP109205 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD210221.

V399 Lacertae has alternative name(s), V399 Lac.

Location of V399 Lacertae

The location of the star in the galaxy 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 star is compared to the celestial equator and is expressed in degrees. For V399 Lacertae, the location is 22h 07m 25.59 and +53 d 18`26.8 .

Proper Motion of V399 Lacertae

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 -3.08 ± 0.19 miliarcseconds/year towards the north and -3.02 ± 0.27 miliarcseconds/year east if we saw them in the horizon.

Physical Properties (Colour, Temperature, Radius) of V399 Lacertae

V399 Lacertae has a spectral type of A3Ib. This means the star is a blue supergiant star. The star has a B-V Colour Index of 0.38 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 6,465 Kelvin. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures. The star's Iron Abundance is -0.05 with an error value of 9.99 Fe/H with the Sun has a value of 1 to put it into context.

V399 Lacertae Apparent and Absolute Magnitudes

V399 Lacertae has an apparent magnitude of 6.17 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 If you used the 2007 Parallax value, you would get an absolute magnitude of -5.42. 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 V399 Lacertae

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as -1.00 which gave the calculated distance to V399 Lacertae as -3261.63 light years away from Earth or -1000 parsecs. It would take a spaceship travelling at the speed of light, -3261.63 years to get there. We don't have the technology or spaceship that can carry people over that distance yet.

In 2007, Hipparcos data was revised with a new parallax of 0.48 which put V399 Lacertae at a distance of 6795.07 light years or 2083.33 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. V399 Lacertae brightness ranges from a magnitude of 6.286 to a magnitude of 6.244 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 0.0 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.

V399 Lacertae Facts

Alternative Names

Traditional/Proper NameV399 Lacertae
Short NameV399 Lac
Hipparcos Library I.D.109205
Bonner DurchmusterungBD+52 3114
Henry Draper Designation210221

Visual Facts

Star Typesupergiant star
Visual / Apparent Magnitude6.17
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)22h 07m 25.59
Declination (Dec.)+53 d 18`26.8
Galactic Latitude-2.05 degrees
Galactic Longitude99.84 degrees
1997 Distance from Earth-1.00 Parallax (milliarcseconds)
 -3261.63 Light Years
 -1000 Parsecs
2007 Revised Distance from Earth0.48 Parallax (milliarcseconds)
 6795.07 Light Years
 2083.33 Parsecs
Proper Motion Dec.-3.08 ± 0.19 milliarcseconds/year
Proper Motion RA.-3.02 ± 0.27 milliarcseconds/year
B-V Index0.38
Radial Velocity-24.40 ± 1.70 km/s
Iron Abundance-0.05 ± 9.99 Fe/H
Spectral TypeA3Ib
Colour(A) blue

Variable Star Details

Mean Variability Period in Days0.029
Variable Magnitude Range (Brighter - Dimmer)6.244 - 6.286

Estimated Facts

Calculated Effective Temperature6,465 Kelvin

Sources and Links

SIMBAD SourceLink

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