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Altarf, Beta Cancri, 17 Cancri, HD69267, HIP40526, HR3249

Altarf (Beta Cancri) is a orange to red star that can be located in the constellation of Cancer. Altarf is the 1st brightest star in Cancer 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. It is calculated at being 1.850 Billion Years old. This information comes from ExoPlanet.

Beta Cancri is the Bayer Classification for the star. The Id of the star in the Yale Bright Star Catalogue is HR3249. HIP40526 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD69267.

Altarf has alternative name(s), Beta Cnc.

Location of Altarf

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 Altarf, the location is 08h 16m 30.95 and +09d 11` 08.4 .

Proper Motion of Altarf

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 -49.24 ± 0.10 miliarcseconds/year towards the north and -46.82 ± 0.19 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 22.94000 km/s with an error of about 0.19 km/s .

Altarf Luminosity

Luminosity is the amount of energy that a star pumps out and its relative to the amount that our star, the Sun gives out. The figure of 45.0000000 that I have given is based on the Spectral Types page that I have found on the Internet. You might find a different figure, one that may have been calculated rather than generalised that I have done. The figure is always the amount times the luminosity of the Sun. It is an imprecise figure because of a number of factors including but not limited to whether the star is a variable star and distance.

Physical Properties (Colour, Temperature, Age, Mass, Radius) of Altarf

Altarf has a spectral type of K4III. This means the star is a orange to red 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 1.48 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 4,025 Kelvin.

Altarf Radius has been calculated as being 33.68 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 23,435,166.22.km. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 35.11. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures. The star's solar mass is 1.70 times that of the Sun's. The Sun's Mass is 1,989,100,000,000,000,000,000 billion kg. which to calculate using this website is too large. To give idea of size, the Sun is 99.86% the mass of the solar system.

The star's metallicity is -0.290000, this value is the fractional amount of the star that is not Hydrogen (X) or Helium (Y). An older star would have a high metallicity whereas a new star would have a lower one.

The star is believed to be about 1.85 Billion years old. To put in context, the Sun is believed to be about five billion years old and the Universe is about 13.8 billion years old.

Altarf Apparent and Absolute Magnitudes

Altarf has an apparent magnitude of 3.53 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 -1.22 If you used the 2007 Parallax value, you would get an absolute magnitude of -1.31. 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 Altarf

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 11.23 which gave the calculated distance to Altarf as 290.44 light years away from Earth or 89.05 parsecs. It would take a spaceship travelling at the speed of light, 290.44 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 10.75 which put Altarf at a distance of 303.41 light years or 93.02 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*.

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.

Altarf Facts

Alternative Names

Traditional/Proper NameAltarf
Flamsteed Name17 Cancri
Flamsteed Short Name17 Cnc
Short NameBeta Cnc
Bayer DesignationBeta Cancri
Hipparcos Library I.D.40526
Yale Bright Star Catalogue (HR) Id3249
Bonner DurchmusterungBD+09 1917
Henry Draper Designation69267

Visual Facts

Star Type star
Age1.85 Billion Years Old
Absolute Magnitude-1.22 / -1.31
Visual / Apparent Magnitude3.53
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)08h 16m 30.95
Declination (Dec.)+09d 11` 08.4
Galactic Latitude23.05 degrees
Galactic Longitude214.25 degrees
1997 Distance from Earth11.23 Parallax (milliarcseconds)
 290.44 Light Years
 89.05 Parsecs
2007 Revised Distance from Earth10.75 Parallax (milliarcseconds)
 303.41 Light Years
 93.02 Parsecs
Galacto-Centric Distance24,367.66 Light Years / 7,471.00 Parsecs
Proper Motion Dec.-49.24 ± 0.10 milliarcseconds/year
Proper Motion RA.-46.82 ± 0.19 milliarcseconds/year
B-V Index1.48
Radial Velocity22.94 ± 0.19 km/s
Iron Abundance-0.17 ± 9.99 Fe/H
Spectral TypeK4III
Colour(K) Orange to Red

Estimated Facts

Luminosity (x the Sun)45.0000000
Calculated Effective Temperature4,025 Kelvin
Mass Compared to the Sun1.70

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
69267+09 1917.0A3.80000-45.00000-52.00000K2Orange

Location of Altarf in Cancer

Altarf (Beta Cancri) Location in Cancer

The map was generated using Night Vision, an awesome free application by Brian Simpson.

Altarf Solar System

This is a N.A.S.A. impression of what the solar system might look like. If the star is not on display, its because its so small compared to the orbits of the outer planets. The green area denotes the habital zone which if the planet is within that area, life could exist. The habital zone might not appear on the picture because its outside the area for the picture. Our planets show the orbit of the planet if its was in our solar system. For more information about the planet and other exoplanetary stuff, visit N.A.S.A.

Altarf Solar System

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