Acamar (Theta Eridani) Star Facts

Acamar, also known as Theta Eridani is a giant star located in the constellation of Eridanus, River Eridanus. Acamar is a major star and forms part of the constellation. Acamar is the traditional/proper name for the star, whilst Theta Eridani is the Bayer Designation for the star. A list of additional names and identifications is in the facts list at the bottom of the page.

Based on the spectral type (A4III+...), Acamar colour is blue - white, although not the hottest stars, they are considerably hotter than our own star which is white.

Acamar temperature is in the range of between 7,500 and 10,000 Kelvin. Based on the spectral type (A4III+...) as we don't have the exact temperature', we can deduce that the surface temperature of Acamar is in the order of 7,500 and 10,000K based on the notes from Harvard University. To put this in context, the temperature of our Sun is about 5,778 Kelvin as said by Google.

Based on a parallax of 20.23, Acamar distance from Earth can be calculated at being 161.23 light years away or 49.46 parsecs.

Acamar is a naked-eye star, so you don't need a telescope or binoculars when you look up on a clear night. The lower the magnitude, the easier it will be to see it.

In the Star Trek Episode, The Vengeance Factor, the planet Acamar III is the location of the humanoid Acamarians. In the episode, the Enterprise is trying to broker a peace deal between the Acamar Sovereign and a group calling themselves the Gatherers. Whilst Jean-Luc Picard deals with the negotiations, William Riker has to deal with a couple of murders linked to the negotiations.

Location

The location of the Acamar in the night sky is determined by the right ascension (R.A.) and declination (Dec.). These are equivalent to the Longitude and Latitude on Earth. The Right Ascension (Longitude) is expressed in time (hh:mm:ss) and is how far the star is along Earth's celestial equator. If the R.A. is positive, then it's eastwards and vice versa.

The Declination (Latitude) is how far north or south the object is compared to the celestial equator and is expressed in degrees. If the value is positive, it is north of the celestial equator. For Acamar, the location is 02h 58m 15.72 and -40° 18` 17.0 .

Based on the location of Eridanus, Acamar can be located in the equatorial region of the celestial sky. The celestial hemisphere is equivalent to the hemispheres on Earth. Being in the equatorial region, Acamar can be seen in both terrestrial hemispheres but there is a caveat of depending how far south and north you are. Acamar is south of the Ecliptic. The Ecliptic is the path that the Earth takes as it orbits the Sun. As the Earth is titled, we therefore have Celestial and Ecliptic hemispheres and they can be different for a star.

Physical Properties

Acamar Luminosity

Luminosity is the amount of energy a star pumps out relative to the amount that our star, the Sun, gives out. Our star, the Sun's value is 1. Acamar luminosity figure of 145.1 is based on the value in the Simbad Hipparcos Extended Catalogue at the University of Strasbourg from 2012. The star generates more energy than our star.

Acamar Size (Radius)

Acamar radius has been calculated as being 2.7 times bigger than the Sun. The Sun's radius is 695,800km, therefore, the Acamar radius is an estimated 1,878,660.km. If you need the star's diameter, you just need to multiply the radius by 2.

Magnitude (Apparent / Absolute / Visible)

A number represents a star’s magnitude, whether apparent/visual or absolute. The smaller the number, the brighter the star is. The Sun is the brightest star and therefore has the lowest of all magnitudes, -26.74. A faint star will have a high number.

Acamar apparent magnitude is 2.88, which is a measure of the star's brightness as seen from Earth. Apparent Magnitude is also known as Visual Magnitude.

If you use the 1997 parallax value, Acamar' absolute magnitude is -0.59. If you use the 2007 parallax value, Acamar' absolute magnitude is -0.59. Absolute Magnitude is the star's apparent magnitude from 10 parsecs or 32.6 light years. The magnitude assumes nothing is between the object and the viewer, such as dust clouds. To compare different stars' actual brightness, you would best use Absolute rather than Apparent Magnitude.

Acamar is visible from Earth without needing binoculars or a telescope. The lower the Apparent Magnitude of a star or other object is, the easier it is to see in the night sky. An object with a magnitude greater than 6.5 cannot be seen without a telescope or other device.

Acamar Fact List

The table is scrollable if you can't see everything, just swipe the table to see the hidden information.

Key Facts

Primary Name:

Spectral Type:

Star Type:

Colour:

Galaxy:

Constellation:

Celestial Hemisphere:

Main Star

Visual / Apparent Magnitude

Visible From Earth

Absolute Magnitude

Radial Velocity

Eccentricity:

Semi-Major Axis

Luminosity (Lsun)

Mass (Solars)

Radius

Location/Coordinates

Right Ascension

Declination

Galactic Latitude

Galactic Longitude

Galacto-Centric Distance:

Distance from Earth

Parallax

Light Years

Parsecs

Astronomical Units (A.U.)

Proper Motion

Declination

Right Ascension

Miscellaneous Facts

B-V Index

Alternate Names