Universe Guide

AA Ceti

AA Ceti Facts

  • AA Ceti is a eclipsing main sequence star that can be located in the constellation of Cetus. The description is based on the spectral class.
  • AA Ceti is not part of the constellation outline but is within the borders of the constellation.
  • Based on the spectral type (A7/8V + G) of the star, the star's colour is blue - white .
  • The star can not be seen by the naked eye, you need a telescope to see it.
  • The star has an estimated age of 1.50 Billion of Years but could be as young as 1.40 to 1.70 according to Hipparcos.
  • Using the most recent figures given by the 2007 Hipparcos data, the star is 362.81 light years away from us. Distance

AA Ceti's Alternative Names

HIP9258 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD12180.

AA Ceti has alternative name(s) :- AA Cet, AA Cet.

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

Location of AA Ceti

The location of the main sequence 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 AA Ceti, the location is 01h 59m 00.66 and -22° 55` 11.6 .

Radial Velocity and Proper Motion of AA Ceti

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 33.25 ± 2.17 milliarcseconds/year towards the north and 94.71 ± 3.63 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 32.70000 km/s with an error of about 2.14 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 AA Ceti

AA Ceti Colour and Temperature

Based on the star's spectral type of A7/8V + G , AA Ceti's colour and type is blue - white main sequence star. The star has a B-V Colour Index of 0.47 which means the star's temperature is about 6,412 Kelvin. The temperature was calculated using information from Morgans @ Uni.edu.

AA Ceti Radius

AA Ceti estimated radius has been calculated as being 7.74 times bigger than the Sun. The Sun's radius is 695,800km, therefore the star's radius is an estimated 5,387,673.81.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 3.9893554368877644539025853975. The figure is derived at by using the formula from SDSS rather than peer reviewed papers. It has been known to produce widely incorrect figures.

AA Ceti Iron Abundance

AA Ceti Iron Abundance is 0.07 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.

AA Ceti Estimated Age

The stars age according to Hipparcos data files put the star at an age of about 1.50 Billion years old but could be between 1.40 and 1.70 Billion years old. In comparison, the Sun's age is about 4.6 Billion Years Old.

AA Ceti Apparent and Absolute Magnitudes

AA Ceti has an apparent magnitude of 6.62 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 -0.05 If you used the 2007 Parallax value, you would get an absolute magnitude of 1.39. 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 AA Ceti

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 4.63000 which gave the calculated distance to AA Ceti as 704.46 light years away from Earth or 215.98 parsecs. If you want that in miles, it is about 4,141,256,430,392,925.90, based on 1 Ly = 5,878,625,373,183.61 miles.

In 2007, Hipparcos data was revised with a new parallax of 8.99000 which put AA Ceti at a distance of 362.81 light years or 111.23 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 22,942,674.53 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 AA Ceti

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 A380736330,579,373.87
Speed of Sound (Mach 1)767.269317,107,063.06
Concorde (Mach 2)1,534.54158,553,324.88
New Horizons Probe33,0007,372,921.79
Speed of Light670,616,629.00362.81

Variable Type of AA Ceti

The star is a eclipsing W Ursae Majoris/Cont 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. AA Ceti brightness ranges from a magnitude of 6.984 to a magnitude of 6.684 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 0.5 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 AA Ceti Facts and Figures

Visual Facts

Primary / Proper / Traditional NameAA Ceti
Alternative NamesAA Cet, HD 12180, HIP 9258, AA Cet
Spectral TypeA7/8V + G
Constellation's Main StarNo
Multiple Star SystemYes
Star Type Main Sequence Dwarf Star
GalaxyMilky Way
Age1.50 Billion Years Old
Age Range1.40 - 1.70 Billion Years Old
Absolute Magnitude -0.05 / 1.39
Visual / Apparent Magnitude6.62
Naked Eye VisibleRequires a 7x50 Binoculars - Magnitudes
Right Ascension (R.A.)01h 59m 00.66
Declination (Dec.)-22° 55` 11.6
Galactic Latitude-74.13968219 degrees
Galactic Longitude201.26611699 degrees
1997 Distance from Earth4.63000 Parallax (milliarcseconds)
 704.46 Light Years
 215.98 Parsecs
2007 Distance from Earth8.99000 Parallax (milliarcseconds)
 362.81 Light Years
 111.23 Parsecs
 22,942,674.53 Astronomical Units
Proper Motion Dec.33.25000 ± 2.17000 milliarcseconds/year
Proper Motion RA.94.71000 ± 3.63000 milliarcseconds/year
B-V Index0.47
Radial Velocity32.70000 ± 2.14 km/s
Iron Abundance0.0700 ± 9.99 Fe/H

Companions (Multi-Star and Exoplanets) Facts

Exoplanet CountNone/Unaware

Variable Star Details

Variable Star ClassEclipsing
Variable Star TypeW Ursae Majoris/Cont
Mean Variability Period in Days0.536
Variable Magnitude Range (Brighter - Dimmer)6.684 - 6.984

Estimated Calculated Facts

Radius (x the Sun)3.99
Effective Temperature6,412 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
12180-23 737.2A7.2000093.0000049.00000F2Yellow/White

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