Universe Guide


Eta Crateris, 30 Crateris, HD103632, HIP58188

Eta Crateris is a blue main sequence dwarf star that can be located in the constellation of Crater. Eta Crateris is the brightest star in Crater 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.

Eta Crateris is the Bayer Classification for the star. HIP58188 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD103632.

Location of Eta Crateris

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 Eta Crateris, the location is 11h 56m 00.98 and -17d09`02.9 .

Proper Motion of Eta Crateris

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 -7.58 ± 0.14 miliarcseconds/year towards the north and -49.74 ± 0.23 miliarcseconds/year east if we saw them in the horizon.

Eta Crateris 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 24.0000000 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, Radius) of Eta Crateris

Eta Crateris has a spectral type of A0V. This means the star is a blue main sequence dwarf star. The star is 7386.00000000 Parsecs from the Galactic Centre or terms of Light Years is 24090.4245878400000000s. The star has a B-V Colour Index of -0.02 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 9,839 Kelvin.

Eta Crateris Radius has been calculated as being 2.60 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 1,809,178.40.km. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 2.30. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures.

Eta Crateris Apparent and Absolute Magnitudes

Eta Crateris has an apparent magnitude of 5.17 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 0.46 If you used the 2007 Parallax value, you would get an absolute magnitude of 0.73. 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 Eta Crateris

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 11.42 which gave the calculated distance to Eta Crateris as 285.61 light years away from Earth or 87.57 parsecs. It would take a spaceship travelling at the speed of light, 285.61 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 12.97 which put Eta Crateris at a distance of 251.48 light years or 77.10 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 7,386.00 Parsecs or 24,090.42 Light Years. The Galacto-Centric Distance is the distance from the star to the Centre of the Galaxy which is Sagittarius A*.

Meteor Showers Radiating from near Eta Crateris

The Eta Craterids Meteor Shower radiants from a point near this star. The meteor shower runs typically between 11-Jan - 22 Jan with a peak date of 16/17 Jan.

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.

Eta Crateris Facts

Alternative Names

Flamsteed Name30 Crateris
Flamsteed Short Name30 Crt
Bayer DesignationEta Crateris
Hipparcos Library I.D.58188
Bonner DurchmusterungBD-16 3358
Henry Draper Designation103632

Visual Facts

Star Typemain sequence dwarf star
Absolute Magnitude0.46 / 0.73
Visual / Apparent Magnitude5.17
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)11h 56m 00.98
Declination (Dec.)-17d09`02.9
Galactic Latitude43.73 degrees
Galactic Longitude284.47 degrees
1997 Distance from Earth11.42 Parallax (milliarcseconds)
 285.61 Light Years
 87.57 Parsecs
2007 Revised Distance from Earth12.97 Parallax (milliarcseconds)
 251.48 Light Years
 77.10 Parsecs
Galacto-Centric Distance24,090.42 Light Years / 7,386.00 Parsecs
Proper Motion Dec.-7.58 ± 0.14 milliarcseconds/year
Proper Motion RA.-49.74 ± 0.23 milliarcseconds/year
B-V Index-0.02
Radial Velocity15.00 ± 4.20 km/s
Spectral TypeA0V
Colour(A) blue

Estimated Facts

Luminosity (x the Sun)24.0000000
Calculated Effective Temperature9,839 Kelvin

Sources and Links

SIMBAD SourceLink

Related Stars

Location of Eta Crateris in Crater

Eta Crateris (Eta Crateris) Location in Crater

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

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