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Caph (Beta Cassiopeiae, 11 Cassiopeiae) Star Facts

Caph Facts

  • Caph is a pulsating subgiant star that can be located in the constellation of Cassiopeia. The description is based on the spectral class.
  • Caph is a main star of the constellation outline.
  • Based on the spectral type (F2III-IV) of the star, the star's colour is yellow to white .
  • Caph is the 73rd brightest star in the night sky and the 3rd brightest star in Cassiopeia 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.
  • The star has an estimated age of 0.90 Billion of Years but could be as young as 0.80 to 1.00 according to Hipparcos.
  • Caph has a radius that is 3.43 times bigger than the Suns. Radius
  • Using the most recent figures given by the 2007 Hipparcos data, the star is 54.74 light years away from us. Distance

Caph's Alternative Names

Beta Cassiopeiae (Bet Cas) is the Bayer Classification for the star. The Bayer Classification was created by Johann Bayer in 1603. The brightest star in the constellation is normally given the Alpha designation, there are exceptions such as Pollux which is Beta Geminorum.

The Id of the star in the Yale Bright Star Catalogue is HR21. HIP746 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD432. The Gliese ID of the star is GL 8. The star was part of the original catalogue devised by German Astronomer Wilheim Gliese of stars located within 20 parsecs of Earth. Star Names

Caph has alternative name(s) :- Al Sanam al Nakah, Bet Cas, bet Cas. In Arabic, it is known as Al-Kaff.

Flamsteed designations are named after the creator, Sir John Flamsteed. Sir John named the stars in the constellation with a number and its latin name, this star's Flamsteed designation is 11 Cassiopeiae. The Flamsteed name can be shortened to 11 Cas.

BD number is the number that the star was filed under in the Durchmusterung or Bonner Durchmusterung, a star catalogue that was put together by the Bonn Observatory between 1859 to 1903. The star's BD Number is BD+58 3.

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

Location of Caph

The location of the subgiant 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 Caph, the location is 00h 09m 10.09 and +59° 09` 00.8 .

Radial Velocity and Proper Motion of Caph

Proper Motion

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 -179.77 ± 0.26 milliarcseconds/year towards the north and 523.50 ± 0.38 milliarcseconds/year east if we saw them in the horizon.

Radial Velocity

The Radial Velocity, that is the speed at which the star is moving away/towards the Sun is 4.30000 km/s with an error of about 0.80 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 of Caph

Caph Temperature and Colour

Based on the star's spectral type of F2III-IV , Caph's colour and type is yellow to white subgiant star. The star's effective temperature is 7,079 Kelvin which is hotter than our own Sun's effective Temperature which is 5,777 Kelvin.

Caph 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 28.82 that I have given is based on the value in the Simbad Hipparcos Extended Catalogue at the University of Strasbourg from 2012.

Caph Radius

Caph Radius has been calculated as being 3.43 times bigger than the Sun. The Sun's radius is 695,800km, therefore the star's radius is an estimated 2,386,594.00.km. If you need the diameter of the star, you just need to multiple the radius by 2.

Caph Mass

The Caph's solar mass is 1.91 times that of our star, the Sun. 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.

Caph Iron Abundance

Caph Iron Abundance is 0.03 with an error value of 9.99 Fe/H with the Sun has a value of 1 to put it into context. The value comes from the Hipparcos Extended Catalog.

Caph Estimated Age

The stars age according to Hipparcos data files put the star at an age of about 0.90 Billion years old but could be between 0.80 and 1.00 Billion years old. In comparison, the Sun's age is about 4.6 Billion Years Old.

Caph Apparent and Absolute Magnitudes

Caph has an apparent magnitude of 2.28 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 1.17 If you used the 2007 Parallax value, you would get an absolute magnitude of 1.16. 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 Caph

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 59.89000 which gave the calculated distance to Caph as 54.46 light years away from Earth or 16.70 parsecs. If you want that in miles, it is about 320,149,937,823,579.40, based on 1 Ly = 5,878,625,373,183.61 miles.

In 2007, Hipparcos data was revised with a new parallax of 59.58000 which put Caph at a distance of 54.74 light years or 16.78 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 3,461,099.33 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 7,408.00 Parsecs or 24,162.18 Light Years. The Galacto-Centric Distance is the distance from the star to the Centre of the Galaxy which is Sagittarius A*.

Travel Time to Caph

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)
Walking49,177,388,567.87
Car120305,912,952.26
Airbus A38073649,877,111.78
Speed of Sound (Mach 1)767.26947,844,438.22
Concorde (Mach 2)1,534.5423,922,187.93
New Horizons Probe33,0001,112,410.74
Speed of Light670,616,629.0054.74

Variable Type of Caph

The star is a pulsating Delta Scuti 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. Caph brightness ranges from a magnitude of 2.379 to a magnitude of 2.346 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 0.1 days (variability).

Meteor Showers Radiating from near Caph

The Beta Cassiopeids Meteor Shower radiants from a point near this star. The meteor shower runs typically between 3 Jul- 19 Aug with a peak date of 29-Jul. The speed of a meteor in the shower is 52 Km/s. The amount of meteors predicted to be seen per hour (Zenith Hourly Rate) is 52.

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 Caph Facts and Figures

Visual Facts


Primary / Proper / Traditional NameCaph
Alternative NamesBeta Cassiopeiae, Bet Cas, Al Sanam al Nakah, Bet Cas, Al-Kaff, HD 432, HIP 746, HR 21, 11 Cassiopeiae, 11 Cas, BD+58 3, Gliese 8, bet Cas
Spectral TypeF2III-IV
Constellation's Main StarYes
Multiple Star SystemYes
Star TypeSubgiant Star
ColourYellow - White
GalaxyMilky Way
ConstellationCassiopeia
Age0.90 Billion Years Old
Age Range0.80 - 1.00 Billion Years Old
Absolute Magnitude 1.17 / 1.16
Visual / Apparent Magnitude2.28
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)00h 09m 10.09
Declination (Dec.)+59° 09` 00.8
Galactic Latitude-3.27721799 degrees
Galactic Longitude117.52688389 degrees
1997 Distance from Earth59.89000 Parallax (milliarcseconds)
 54.46 Light Years
 16.70 Parsecs
2007 Distance from Earth59.58000 Parallax (milliarcseconds)
 54.74 Light Years
 16.78 Parsecs
 3,461,099.33 Astronomical Units
Galacto-Centric Distance24,162.18 Light Years / 7,408.00 Parsecs
Proper Motion Dec.-179.77000 ± 0.26000 milliarcseconds/year
Proper Motion RA.523.50000 ± 0.38000 milliarcseconds/year
B-V Index0.3
Radial Velocity4.30000 ± 0.80 km/s
Iron Abundance0.0300 ± 9.99 Fe/H
Eccentricity0.10610
Semi-Major Axis7447.0000000
Stellar Luminosity (Lsun)28.8200000
Brightest in Night Sky73rd

Companions (Multi-Star and Exoplanets) Facts


Exoplanet CountNone/Unaware

Variable Star Details


Variable Star ClassPulsating
Variable Star TypeDelta Scuti
Mean Variability Period in Days0.101
Variable Magnitude Range (Brighter - Dimmer)2.346 - 2.379

Estimated Calculated Facts


Radius (x the Sun)3.43 - 3.00
Effective Temperature7,218 Kelvin
Mass Compared to the Sun1.91

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
432+58 3.0A2.40000530.00000-177.00000F5Yellow/White
B13.700001935

Location of Caph in Cassiopeia


Caph Location in Cassiopeia

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

Cassiopeia Main Stars


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