Cursa, designated as Beta Eridani, is the second-brightest star in the constellation of Eridanus, the celestial river. Cursa is located in the northeast end of this constellation near the shared border with Orion.
Key Facts & Summary
- Cursa is located at around 89 light-years / 27.4 parsecs away from our Sun.
- It is a single star, and it can be viewed with the naked eye since it has an apparent magnitude of 2.796 and an absolute magnitude of around +0.59.
- Cursa is a giant star of spectral type A3 III. It is white-hued just like a typical A-type star.
- Cursa has around 2.0 solar masses, and around 2.4 solar radii, being more than twice as big as our Sun.
- This star is also hotter than our Sun, having surface average temperatures of around 8,360 K.
- Cursa is around 25 times brighter than our Sun.
- This star is a fast-spinning star, having a rotational velocity of 196 km / 121.7 mi per second.
- The radial velocity of Cursa is -3.6 km / -2.2 mi per second.
- The surface gravity on this star has been recorded at around 3.58 cgs.
- This star has been observed to vary in apparent visual magnitude, ranging between 2.72 and 2.80.
- A particularly strong flare was reported about this star in 1985.
- The location and trajectory of this star suggest that is is a member of the Ursa Major supergroup, an association of stars that share a common origin and motion through space. However, its photometric properties indicate that it may be an interloper.
- Cursa has an optical companion star with an apparent magnitude of 10.90, at an angular separation of 120 arcseconds and a position angle of 148o.
- The best time to observe Cursa and the other stars in Eridanus is during the month of December.
- Eridanus is among the first 48 constellations listed by Ptolemy.
Beta Eridani has the traditional name Cursa, which is derived from Al Kursiyy al Jauzah, which translates to “the Chair (or Footstool”) of the Central One”.
Cursa is the name associated with this star along with Lambda Eridani, Psi Eridani, and Tau Orionis. In 2016, the IAU decided to officially approve a name for Beta Eridani, and it is now known as Cursa. This star was named as such due to its position in the sky. It is situated south of Orion’s foot.
Cursa / Beta Eridani formed out of an interstellar medium of dust and gas. Gravity pulled the swirling gas and dust together and when it reached the right temperature, the second-brightest star in Eridani, Cursa, was born.
If this star is indeed associated with the Ursa Major supergroup, an association of stars that share a common origin and motion through space, then its age and origin will be properly estimated.
Distance, Size, and Mass
Cursa / Beta Eridani is located at around 89 light-years / 27.4 parsecs away from the Sun. It is bright enough to be visible to the naked eye under the right conditions.
Cursa is larger and more massive than our Sun. It has around 2.0 solar masses, or 200% of our Sun’s mass, and 2.4 solar radii, or 240% of our Sun’s radius. This star is around four times bigger than our Sun.
Cursa is a giant star of spectral type A3 III. It is white-hued just like a typical A-type star. It has consumed its hydrogen at its core and evolved away from the main-sequence.
Cursa has an apparent magnitude of 2.796 and an absolute magnitude of around +0.59. This star has been observed to vary in apparent visual magnitude, ranging between 2.72 and 2.80.
This star is 25 times brighter than our Sun, and 1.4 times hotter, having surface temperatures of around 8,360 K. It is a fast-spinning star, having a rotational velocity of 196 km / 121.7 mi per second.
The radial velocity of Cursa is -3.6 km / -2.2 mi per second. A particularly strong flare was reported about this star in 1985, and it has never happened since then.
Cursa is a single star, however, it has an optical companion star with an apparent magnitude of 10.90, at an angular separation of 120 arcseconds and a position angle of 148o.
Cursa / Beta Eridani is located in the constellation of Eridanus, the celestial river. It is the second-brightest star in Eridanus, after Achernar.
Cursa is located in the northeast end of Eridanus, near the shared border with the constellation of Orion. Eridanus is among the first 48 constellations listed by the Greco-Roman astronomer Ptolemy, in his 2nd century Almagest.
Eridanus is the 6th largest constellation in the sky, stretching for around 1,138 square degrees. This constellation hosts many interesting stars and deep-sky objects.
Some of them are, the blue star Achernar, which is the brightest star in Eridanus, Acamar, a binary star system, 39 Eridani, 40 Eridani, p Eridani, or Ran which hosts a planet very similar to Jupiter, the planetary nebula NGC 1535, the reflection nebula IC 2118, the galaxies NGC 1232, NGC 1234, NGC 1291, or the spiral galaxy NGC 1300.
Eridanus is located in the first quadrant of the southern hemisphere (SQ1) and can be seen at latitudes between +32o and -90o. The best time to observe the stars and deep-sky objects in Eridanus, is during December, at 21:00 ( 9 p.m.).
Cursa / Beta Eridani will continue to evolve in the next phases of its star life. The star seems stable enough and will continue to remain so for many millions of years. Until its origin and age are predicted, Cursa’s future remains a bit hard to predict.
Did you know?
- The Chinese have an asterism known as the Jade Well, of which Cursa, along with Lambda Eridani, Psi Eridani, and Tau Orionis are part of.
- The Chinese know the star Cursa as Yu Jing san – the Third Star of Jade Well. In older texts, Yu Jing was also spelled Yuh Tsing.
- Cursa has the catalog identifier CCDM J05079-0506B.
- The stars of the modern constellation of Fornax were formally part of Eridanus.
- Eridanus is called Srotaswini in Sanskrit, meaning the course or stream of the river.
- Many of the stars of Eridanus can’t be seen from China, and thus, the Chinese selected the northern part of Eridanus to be located within the White Tiger of the West, while the unseen southern part was classified among the Southern Asterisms.