Epsilon Geminorum facts for kids
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| Observation data Epoch J2000 Equinox J2000 |
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|---|---|
| Constellation | Gemini |
| Right ascension | 06h 43m 55.927s |
| Declination | +25° 07′ 52.06″ |
| Apparent magnitude (V) | +3.06 |
| Characteristics | |
| Spectral type | G8 Ib |
| U−B color index | +1.46 |
| B−V color index | +1.40 |
| Astrometry | |
| Radial velocity (Rv) | +8.09±0.14 km/s |
| Proper motion (μ) | RA: −4.835 mas/yr Dec.: −11.78 mas/yr |
| Parallax (π) | 3.748 ± 0.184 mas |
| Distance | 861+52 −39 ly (264+16 −12 pc) |
| Absolute magnitude (MV) | −4.33±0.10 |
| Details | |
| Mass | 5.29±0.04 – 8.2±0.82 M☉ |
| Radius | 130.2+5.5 −6.0 R☉ |
| Luminosity | 6,980 L☉ |
| Surface gravity (log g) | 0.76–1.38 cgs |
| Temperature | 4,591±11 K |
| Metallicity [Fe/H] | 0.15±0.07 dex |
| Rotational velocity (v sin i) | 9.08 km/s |
| Age | 100 Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
Epsilon Geminorum, also known as Mebsuta, is a bright star in the constellation of Gemini. You can find it in the part of the constellation that looks like the outstretched right leg of the twin Castor. This star shines with an apparent visual magnitude of +3.06, making it one of the easier stars to spot in Gemini. Mebsuta is quite far away from us, about 860 light-years from Earth.
Contents
Discovering Epsilon Geminorum: Mebsuta's Story
What's in a Name? Understanding Mebsuta
The scientific name for this star is Epsilon Geminorum, which is a Bayer designation. This system uses Greek letters and the constellation name. However, it also has a traditional name, Mebsuta. This name comes from ancient Arabian astronomers. They imagined Mebsuta and another star, Mekbuda (Zeta Geminorum), as the paws of a giant lion stretching across the sky. Mebsuta means "the outstretched paw" in Arabic.
In 2016, the International Astronomical Union (IAU) created a group called the Working Group on Star Names (WGSN). This group helps to officially name and standardize star names. They approved Mebsuta as the official name for this star.
Mebsuta in Chinese Astronomy
In Chinese astronomy, Epsilon Geminorum is part of an asterism called 井宿 (Jǐng Su), which means Well. This asterism includes several stars in Gemini. Because of this, Epsilon Geminorum is also known as 井宿五 (Jǐng Su wǔ), meaning "the Fifth Star of Well."
Exploring Mebsuta: A Giant Star's Secrets
Mebsuta's Stellar Classification
Epsilon Geminorum is classified as a G8 Ib star. The "G8" tells us its color and temperature, while "Ib" means it's a lower luminosity supergiant star. Supergiants are much larger and brighter than our Sun. Mebsuta is about 5.3 times more massive than our Sun. Scientists estimate it is around 100 million years old. Since 1943, the unique light spectrum of Mebsuta has been used as a standard to help classify other stars.
How Big is Mebsuta? Measuring its Size
Using special tools called interferometry, scientists have directly measured Mebsuta's size. Its radius is an amazing 130 times larger than the radius of the Sun! This huge star shines with about 7,000 times the luminosity of the Sun. Its outer atmosphere has a temperature of about 4,591 K. This temperature gives Mebsuta its distinct yellow glow, typical of a G-type star. Scientists have also detected a magnetic field on its surface.
Mebsuta's Cosmic Dance: Occultations
What is an Occultation?
An occultation happens when one celestial object passes in front of another, blocking its light from our view. Because Epsilon Geminorum is located close to the ecliptic (the path the Sun, Moon, and planets appear to follow in the sky), it can sometimes be hidden by the Moon or a planet.
Planets and Asteroids Passing By
Mebsuta has been occulted several times throughout history. On April 8, 1976, the planet Mars passed in front of Epsilon Geminorum. This event allowed scientists to measure the shape of Mars' outer atmosphere. Earlier, on June 10, 1940, the planet Mercury also occulted Mebsuta. More recently, on September 3, 2015, the asteroid 112 Iphigenia passed in front of the star.
Mebsuta's Legacy: In Culture
A Star's Name on a Ship
The star's traditional name, Melucta (another version of Mebsuta), was used for a United States Navy ship. The USS Melucta (AK-131) was a cargo ship that served during its time.
