Universe Guide

AL Draconis

AL Draconis Facts

  • AL Draconis is a pulsating variable star that can be located in the constellation of Draco. The description is based on the spectral class.
  • AL Draconis is not part of the constellation outline but is within the borders of the constellation.
  • Based on the spectral type (M7ea) of the star, the star's colour is 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 918.77 light years away from us. Distance

AL Draconis's Alternative Names

HIP90474 is the reference name for the star in the Hipparcos Star Catalogue.

AL Draconis has alternative name(s) :- AL Dra, AL Dra.

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

Location of AL Draconis

The location of the variable 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 AL Draconis, the location is 18h 27m 40.55 and +49° 18` 33.5 .

Proper Motion of AL Draconis

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 -14.86 ± 2.08 milliarcseconds/year towards the north and 0.99 ± 2.64 milliarcseconds/year east if we saw them in the horizon. . 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 AL Draconis

AL Draconis Temperature and Colour

Based on the star's spectral type of M7ea , AL Draconis's colour and type is red variable star. The star has a B-V Colour Index of 1.5 which means the star's temperature is about 4,014 Kelvin. The temperature was calculated using information from Morgans @ Uni.edu.

AL Draconis Radius

AL Draconis Apparent and Absolute Magnitudes

AL Draconis has an apparent magnitude of 12.38 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 5.13. 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 AL Draconis

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as -0.61000 which gave the calculated distance to AL Draconis as -5346.94 light years away from Earth or -1639.34 parsecs. If you want that in miles, it is about -31,432,657,152,890,371.65, based on 1 Ly = 5,878,625,373,183.61 miles.

In 2007, Hipparcos data was revised with a new parallax of 3.55000 which put AL Draconis at a distance of 918.77 light years or 281.69 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 58,102,328.41 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 AL Draconis

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 A380736837,150,054.66
Speed of Sound (Mach 1)767.269803,033,147.73
Concorde (Mach 2)1,534.54401,516,050.56
New Horizons Probe33,00018,670,983.04
Speed of Light670,616,629.00918.77

Variable Type of AL Draconis

The star is a pulsating Omicron Ceti 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. AL Draconis brightness ranges from a magnitude of 13.029 to a magnitude of 9.828 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 335.8 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 AL Draconis Facts and Figures

Visual Facts

Primary / Proper / Traditional NameAL Draconis
Alternative NamesAL Dra, HIP 90474, AL Dra
Spectral TypeM7ea
Constellation's Main StarNo
Multiple Star SystemNo / Unknown
Star TypeVariable Star
GalaxyMilky Way
Absolute Magnitude / 5.13
Visual / Apparent Magnitude12.38
Naked Eye VisibleRequires a 4.5 - 6 Inch Telescope - Magnitudes
Right Ascension (R.A.)18h 27m 40.55
Declination (Dec.)+49° 18` 33.5
Galactic Latitude23.94120376 degrees
Galactic Longitude77.73608399 degrees
1997 Distance from Earth-0.61000 Parallax (milliarcseconds)
 -5346.94 Light Years
 -1639.34 Parsecs
2007 Distance from Earth3.55000 Parallax (milliarcseconds)
 918.77 Light Years
 281.69 Parsecs
 58,102,328.41 Astronomical Units
Proper Motion Dec.-14.86000 ± 2.08000 milliarcseconds/year
Proper Motion RA.0.99000 ± 2.64000 milliarcseconds/year
B-V Index1.5

Companions (Multi-Star and Exoplanets) Facts

Exoplanet CountNone/Unaware

Variable Star Details

Variable Star ClassPulsating
Variable Star TypeOmicron Ceti
Mean Variability Period in Days335.800
Variable Magnitude Range (Brighter - Dimmer)9.828 - 13.029

Estimated Calculated Facts

Effective Temperature4,014 Kelvin

Sources and Links

SIMBAD SourceLink

Related Stars

Comments and Questions

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