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12 Lacertae, HD214993, HIP112031, HR8640

12 Lacertae is a blue pulsating star that can be located in the constellation of Lacerta. The star can be seen with the naked eye, that is, you don't need a telescope/binoculars to see it.

The Id of the star in the Yale Bright Star Catalogue is HR8640. HIP112031 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD214993.

12 Lacertae has alternative name(s), DD Lac.

Location of 12 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 12 Lacertae, the location is 22h 41m 28.65 and +40d 13` 31.7 .

Proper Motion of 12 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 -5.33 ± 0.20 miliarcseconds/year towards the north and -1.59 ± 0.29 miliarcseconds/year east if we saw them in the horizon. The Radial Velocity, that is the speed at which the star is moving away/towards us is -12.50000 km/s with an error of about 2.20 km/s .

Physical Properties (Colour, Temperature, Radius) of 12 Lacertae

12 Lacertae has a spectral type of B2IIIv SB. This means the star is a blue star. The star is 7471.00000000 Parsecs from the Galactic Centre or terms of Light Years is 24367.6634302400000000s. The star has a B-V Colour Index of -0.13 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 12,762 Kelvin.

12 Lacertae Radius has been calculated as being 7.26 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 5,053,343.50.km. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 7.00. 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 -0.41 with an error value of 9.99 Fe/H with the Sun has a value of 1 to put it into context.

12 Lacertae Apparent and Absolute Magnitudes

12 Lacertae has an apparent magnitude of 5.25 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 -2.90 If you used the 2007 Parallax value, you would get an absolute magnitude of -2.82. 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 12 Lacertae

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 2.34 which gave the calculated distance to 12 Lacertae as 1393.86 light years away from Earth or 427.35 parsecs. It would take a spaceship travelling at the speed of light, 1393.86 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 2.43 which put 12 Lacertae at a distance of 1342.24 light years or 411.52 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.

The star's Galacto-Centric Distance is 7,471.00 Parsecs or 24,367.66 Light Years. The Galacto-Centric Distance is the distance from the star to the Centre of the Galaxy which is Sagittarius A*.

Variable Type of 12 Lacertae

The star is a pulsating Beta Cephei 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. 12 Lacertae brightness ranges from a magnitude of 5.238 to a magnitude of 5.152 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 0.2 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.

12 Lacertae Facts

Alternative Names

Traditional/Proper Name12 Lacertae
Flamsteed Name12 Lacertae
Flamsteed Short Name12 Lac
Short NameDD Lac
Hipparcos Library I.D.112031
Yale Bright Star Catalogue (HR) Id8640
Bonner DurchmusterungBD+39 4912
Henry Draper Designation214993

Visual Facts

Star Type star
Absolute Magnitude-2.90 / -2.82
Visual / Apparent Magnitude5.25
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)22h 41m 28.65
Declination (Dec.)+40d 13` 31.7
Galactic Latitude-16.18 degrees
Galactic Longitude97.65 degrees
1997 Distance from Earth2.34 Parallax (milliarcseconds)
 1393.86 Light Years
 427.35 Parsecs
2007 Revised Distance from Earth2.43 Parallax (milliarcseconds)
 1342.24 Light Years
 411.52 Parsecs
Galacto-Centric Distance24,367.66 Light Years / 7,471.00 Parsecs
Proper Motion Dec.-5.33 ± 0.20 milliarcseconds/year
Proper Motion RA.-1.59 ± 0.29 milliarcseconds/year
B-V Index-0.13
Radial Velocity-12.50 ± 2.20 km/s
Iron Abundance-0.41 ± 9.99 Fe/H
Spectral TypeB2IIIv SB
Colour(B) blue

Variable Star Details

Variable Star ClassPulsating
Variable Star TypeBeta Cephei
Mean Variability Period in Days0.193
Variable Magnitude Range (Brighter - Dimmer)5.152 - 5.238

Estimated Facts

Calculated Effective Temperature12,762 Kelvin

Sources and Links

SIMBAD SourceLink

Related Stars

Multi-Star System

The star has been identified as being a multi-star system, one in which there is at least one star in close orbit to another star or two or more stars orbiting a central point. The stars may be of equal mass, unequal mass where one star is stronger than the other or be in groups orbiting a central point which doesn't necessarily have to be a star. More information can be found on my dedicated multiple star systems page. The source of the info is Simbad. The file is dated 2000 so any differences between this and any other source will be down to the actual source from where the information came from.

Proper Motion mas/yr
H.D. IdB.D. IdStar CodeMagnitudeR.A.Dec.SpectrumColourYear
214993+39 4912.0A5.20000-1.00000-2.00000B2Blue/White

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