Rigel facts for kids
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| Observation data Epoch J2000.0 Equinox J2000.0 |
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|---|---|
| Constellation | Orion |
| Pronunciation | or |
| A | |
| Right ascension | 05h 14m 32.27210s |
| Declination | −08° 12′ 05.8981″ |
| Apparent magnitude (V) | 0.13 (0.05–0.18) |
| BC | |
| Right ascension | 05h 14m 32.049s |
| Declination | −08° 12′ 14.78″ |
| Apparent magnitude (V) | 6.67 (7.5/7.6) |
| Characteristics | |
| A | |
| Evolutionary stage | Blue supergiant |
| Spectral type | B8 Ia |
| U−B color index | −0.66 |
| B−V color index | −0.03 |
| Variable type | Alpha Cygni |
| BC | |
| Evolutionary stage | Main sequence |
| Spectral type | B9V + B9V |
| Astrometry | |
| A | |
| Radial velocity (Rv) | 17.8±0.4 km/s |
| Proper motion (μ) | RA: +1.31 mas/yr Dec.: +0.50 mas/yr |
| Parallax (π) | 3.78 ± 0.34 mas |
| Distance | 848±65 ly (260±20 pc) |
| Absolute magnitude (MV) | −7.84 |
| BC | |
| Radial velocity (Rv) | 17.8±0.4 km/s |
| Proper motion (μ) | RA: −0.034 mas/yr Dec.: −0.017 mas/yr |
| Parallax (π) | 3.2352 ± 0.0553 mas |
| Distance | 1,010 ± 20 ly (309 ± 5 pc) |
| Orbit | |
| Primary | A |
| Companion | BC |
| Period (P) | 24,000 yr |
| Orbit | |
| Primary | Ba |
| Companion | Bb |
| Period (P) | 9.860 days |
| Eccentricity (e) | 0.1 |
| Semi-amplitude (K1) (primary) |
25.0 km/s |
| Semi-amplitude (K2) (secondary) |
32.6 km/s |
| Orbit | |
| Primary | B |
| Companion | C |
| Period (P) | 63 yr |
| Details | |
| A | |
| Mass | 21±3 M☉ |
| Radius | 74.1+6.1 −7.3 R☉ |
| Luminosity (bolometric) | 120,000+25,000 −21,000 L☉ |
| Surface gravity (log g) | 1.75±0.10 cgs |
| Temperature | 12,100±150 K |
| Metallicity [Fe/H] | −0.06±0.10 dex |
| Rotational velocity (v sin i) | 25±3 km/s |
| Age | 8±1 Myr |
| Ba | |
| Mass | 3.84 M☉ |
| Bb | |
| Mass | 2.94 M☉ |
| C | |
| Mass | 3.84 M☉ |
| Other designations | |
| A: Rigel, Algebar, Elgebar, 19 Orionis, HD 34085, HR 1713, HIP 24436, SAO 131907, BD−08°1063, FK5 194 | |
| B: Rigel B, GCRV 3111 | |
| Database references | |
| SIMBAD | Rigel |
| Rigel B | |
Rigel is a brilliant blue supergiant star found in the famous constellation of Orion. Its official name is Beta Orionis (β Orionis), and it is one of the brightest stars you can see in the night sky.
To the naked eye, Rigel looks like a single, bright blue-white point of light. But it is actually a star system with at least four stars. This amazing system is about 850 light-years away from Earth.
The main star, Rigel, is a B8Ia spectral type star. This means it is incredibly hot and bright. It shines with the light of 60,000 to 360,000 of our Suns! It is also huge, with a radius more than 70 times that of the Sun.
Rigel is a young star, only about 7 to 9 million years old. It has already used up the hydrogen fuel in its core and has swollen into a supergiant. One day, it will end its life in a massive explosion called a supernova.
Contents
What's in a Name?
The name Rigel was officially recognized by the International Astronomical Union (IAU) in 2016. The name comes from Arabic, Rijl Jauzah al Yusrā, which means "the left foot of Jauzah." Jauzah was an old Arabic name for the constellation Orion. So, Rigel is the "foot" of the great hunter in the sky.
Rigel's official scientific name is β Orionis (Beta Orionis). Usually, the "Beta" star is the second-brightest in a constellation. However, Rigel is almost always brighter than α Orionis (Betelgeuse). Astronomers think that when the names were given long ago, the variable star Betelgeuse might have been temporarily brighter than Rigel.
How to Find Rigel in the Sky
Rigel is very easy to find. It is the seventh-brightest star in the night sky and the brightest star in the constellation Orion. It shines with a distinct blue-white light, which makes a beautiful contrast with the reddish color of Betelgeuse, the other bright star in Orion.
In the Northern Hemisphere, Rigel is a bright beacon in the winter sky. In the Southern Hemisphere, it is a star of summer. Rigel is part of a famous star pattern called the "Winter Hexagon". This asterism also includes the bright stars Aldebaran, Capella, Pollux, Procyon, and Sirius.
Because it is so bright and easy to locate, sailors have used Rigel for navigation for centuries.
A Pulsating Star
Rigel's brightness is not perfectly steady. It changes very slightly, in a way that is hard to see without special instruments. This is because the star's atmosphere is unstable and pulsates, like a slow, giant heartbeat.
Stars that behave this way are called Alpha Cygni variables. These are supergiant stars that have complex pulsations, causing their brightness to vary. Scientists study these small changes in light to learn more about the inside of this massive star.
How Far Away Is Rigel?
Measuring the exact distance to faraway stars is very difficult. The best estimate from the Hipparcos satellite places Rigel at about 863 light-years from Earth. This means the light we see from Rigel tonight started its journey around the year 1162!
Rigel is part of a group of stars called the Orion OB1 association. It is so powerful that its light illuminates several nearby dust clouds, or nebulae. The most famous of these is the Witch Head Nebula, which glows because it reflects Rigel's blue light.
A System of Multiple Stars
| Rigel | |||||||||||||||
| Separation = 9.5″ Period = 24,000 y |
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| Ba | |||||||||||||||
| Separation = 0.58 mas Period = 9.860 d |
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| Bb | |||||||||||||||
| Separation = 0.1″ Period = 63 y |
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| C | |||||||||||||||
A chart showing how the stars in the Rigel system are organized.
What looks like one star is actually a fascinating system of at least four stars orbiting each other.
- Rigel A: This is the main blue supergiant star that we see. It is huge and incredibly bright.
- Rigel B: This is a companion star that can be seen with a telescope. It is much fainter than Rigel A. But Rigel B is not just one star! It is a close triple-star system.
- Rigel Ba and Rigel Bb: These two stars are very close together. They orbit each other every 10 days. They are both hot, blue-white stars.
- Rigel C: This star orbits the Ba/Bb pair. It takes about 63 years to complete one orbit.
The Rigel B/C system is very far from Rigel A. They are separated by over 2,200 times the distance from the Earth to the Sun. It would take them about 24,000 years to orbit each other once.
Amazing Facts About Rigel
Rigel is a blue supergiant star. It has used up the hydrogen fuel in its core and has expanded to a giant size. It is one of the most luminous stars known in our galaxy.
- Temperature: Its surface temperature is about 12,100 K. This is more than twice as hot as our Sun.
- Mass: Rigel is about 21 times more massive than the Sun.
- Size: Its radius is about 74 times larger than the Sun's. If Rigel were at the center of our solar system, it would stretch out almost to the orbit of Mercury.
- Luminosity: It shines with the light of about 120,000 Suns. This incredible brightness is why we can see it from so far away.
The other stars in the system (Rigel Ba, Bb, and C) are also impressive. They are all hot B-type stars, each about three to four times as massive as the Sun.
The Future of Rigel
Because Rigel is so massive, it will have a short and dramatic life. It is already a supergiant, which means it is near the end of its life cycle.
In a few million years, Rigel is expected to explode as a type II supernova. When this happens, it will briefly shine brighter than the Moon in our sky. It will be visible during the day.
The supernova explosion will leave behind a very dense object, either a neutron star or a black hole. Rigel is one of the closest stars to Earth that will one day become a supernova.
Rigel in Cultures Around the World
For thousands of years, people all over the world have told stories about Rigel.
- Arabic Lore: As mentioned, its name comes from the Arabic word for "foot," marking the foot of Orion the giant.
- Australia: The Wotjobaluk people of southeastern Australia saw Rigel as Yerrerdet-kurrk, the mother-in-law of the star Altair.
- New Zealand: To the Māori people, Rigel is called Puanga. Its appearance in the morning sky helped mark the start of the Māori New Year.
- Japan: In Japan, one clan chose Rigel and its white color as their symbol, calling it Genji-boshi. Their rival clan chose the red star Betelgeuse. The two stars were seen as great rivals in the sky.
- Norse Mythology: Some believe Rigel was known as "Aurvandil's toe" in Norse myths.
See also
In Spanish: Rigel para niños
