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Suhail, Lambda Velorum, HD78647, HIP44816, HR3634

Suhail (Lambda Velorum) is a orange to red pulsating luminous giant star that can be located in the constellation of Vela. The description is based on the spectral class. Suhail is a main star of the constellation.

Suhail is the 64th brightest star in the night sky and the 3rd brightest star in Vela 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.

Suhail's Alternative Names

Lambda Velorum (Lam Vel) is the Bayer Classification for the star. The Id of the star in the Yale Bright Star Catalogue is HR3634. HIP44816 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD78647.

Suhail has alternative name(s) :- Al Suhail, lam Vel.

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

Location of Suhail

The location of the 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 star is compared to the celestial equator and is expressed in degrees. For Suhail, the location is 09h 07m 59.78 and -43° 25` 57.4 .

Radial Velocity and Proper Motion of Suhail

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 13.52 ± 0.09 miliarcseconds/year towards the north and -24.01 ± 0.11 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 the Sun is 17.60 km/s with an error of about 0.30 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 (Colour, Temperature) of Suhail

Suhail has a spectral type of K4Ib-II. This means the star is a orange to red luminous giant star. The star is 7,414.00 Parsecs from the Galactic Centre or terms of Light Years is 24,181.75 s. The star has a B-V Colour Index of 1.66 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 3,595 Kelvin.

Suhail Radius has been calculated as being 151.20 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 105,203,263.62.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 143.73. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures.

Suhail Apparent and Absolute Magnitudes

Suhail has an apparent magnitude of 2.23 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 -3.99 If you used the 2007 Parallax value, you would get an absolute magnitude of -3.88. 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 Suhail

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 5.69 which gave the calculated distance to Suhail as 573.22 light years away from Earth or 175.75 parsecs. It would take a spaceship travelling at the speed of light, 573.22 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 5.99 which put Suhail at a distance of 544.51 light years or 166.94 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 34,433,606.82 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.

The star's Galacto-Centric Distance is 7,414.00 Parsecs or 24,181.75 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 Suhail

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. Suhail brightness ranges from a magnitude of 2.376 to a magnitude of 2.294 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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Suhail Facts

Visual Facts


Primary / Proper / Traditional NameSuhail
Alternative NamesLambda Velorum, Lam Vel, Al Suhail, HD 78647, HIP 44816, HR 3634, lam Vel
Spectral TypeK4Ib-II
Constellation's Main StarYes
Multiple Star SystemYes
Star TypeLuminous Giant Star
Colour orange to red
GalaxyMilky Way
ConstellationVela
Absolute Magnitude -3.99 / -3.88
Visual / Apparent Magnitude2.23
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)09h 07m 59.78
Declination (Dec.)-43° 25` 57.4
Galactic Latitude2.82 degrees
Galactic Longitude265.94 degrees
1997 Distance from Earth5.69 Parallax (milliarcseconds)
 573.22 Light Years
 175.75 Parsecs
2007 Distance from Earth5.99 Parallax (milliarcseconds)
 544.51 Light Years
 166.94 Parsecs
 34,433,606.82 Astronomical Units
Galacto-Centric Distance24,181.75 Light Years / 7,414.00 Parsecs
Proper Motion Dec.13.52 ± 0.09 milliarcseconds/year
Proper Motion RA.-24.01 ± 0.11 milliarcseconds/year
B-V Index1.66
Radial Velocity17.60 ± 0.30 km/s
Eccentricity0.02
Semi-Major Axis7323.00
Brightest in Night Sky 64th

Companions (Multi-Star and Exoplanets) Facts


Exoplanet CountNone/Unaware

Variable Star Details


Variable Star ClassPulsating
Variable Star TypeSlow Irregular
Mean Variability Period in Days0.068
Variable Magnitude Range (Brighter - Dimmer)2.294 - 2.376

Estimated Facts


Calculated Effective Temperature3,595 Kelvin

Sources and Links


SIMBAD SourceLink

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
78647-42 4990.2A2.20000-22.0000012.00000K4Orange
B14.800001897

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