| Home > Stars > Non-Contrast Multiple Stars > Gamma Arietis |
Gamma (γ) Arietis
Binary (Double) Star
| Right Ascension | 01h 52m 08s | Best Seen | 10/15 - 2/15 |
| Declination | 19° 10' 18" | Combined Magnitude | 3.9 |
| Apparent Separation | -- | Constellation | Aries |
Actual |
Compared to Sun |
|
| Distance | 160 ly | -- |
| Separation | 36 billion miles | 385 au |
| Orbital Period | > 5,000 yrs | -- |
| Variable Period | 2.6 days (magnitude range: +4.62 to +4.66) |
-- |
| Actual Brightness | -- | 50 / 1 |
| Magnitude | 4.78 / 4.83 | -- |
| Mass | -- | -- |
| Surface Gravity | -- | -- |
| Surface Composition (by mass) | 74% hydrogen 24% helium 2% everything else |
same |
| Spectral Type | -- | G2 V |
| Density (gram/cubic cm) | -- | -- |
What To Look For Through The Telescope
-
Recommended eyepiece: 24mm or 40mm
-
When people look through the telescope they should see two stars next to each other. In this case the two stars should be about the same brightness.
Gamma Arietis Information:
-
This is a variable double star in Aries, also known as Mesarthim (derived from an Arabic name of unknown meaning…maybe from Hebrew word meaning “minister”)
-
Discovered as a double star in 1664 by Robert Hooke.
-
Both stars are very similar in appearance, but easily separated by a telescope.
-
“The First Star of Aries” because during ancient times, it was the closest of the Ram’s star’s to the vernal equinox. (Precession, the 26,000 year wobble of the Earth’s axis, has since shifted the equinox westward to Pisces.)
-
A double star is simply two stars that revolve around each other much like the Earth orbits the sun.
-
Over half of the stars in the sky are double or multiple star systems. They can't be seen as individual stars because they are too far away and too close together. A good analogy is the headlights of a distant car.
-
At least one multiple star system has as many as 9 components.
-
Note that the sun is just an ordinary star.
-
The stars in this system have not shown a change in position angle in 300 years.
a. Gamma1
Temperature 19,000 °F Diameter 2.03 Suns Spectral Type blue white star (main sequence) B-V Color Index -0.02, blue-white Luminosity 56 Suns, visual Magnitude +4.83 Mass 2.8 Suns b. Gamma2
Temperature 16,000 - 17,600 °F Diameter 3.38 Suns Spectral Type peculiar (see below) B-V Color Index -0.05, blue-white Luminosity 43 - 52 Suns, visual Magnitude variable Mass 2.5 Suns -
While Gamma1 is relatively ordinary, Gamma2 is an "Ap" star, the "p" standing for (spectrally) "peculiar." It is now known that such stars are actually highly magnetized, Mesarthim2's magnetic field roughly 1000 times the strength of Earth's. The magnetism is concentrated into zones in which it aids in the separation of chemical elements (Gamma2 notably high in silicon). As the star rotates, these concentrations swing in and out of view, allowing the rotation period to be found (in this case 1.609 days) and causing subtle visual variations. Sophisticated spectroscopic examination and measures of Doppler shifts allow astronomers to create "pictures" of the surfaces of such stars, Gamma2 having the distinction of being the first to be so treated.
| Home > Stars > Non-Contrast Multiple Stars > Gamma Arietis | top |
References
| Item | Updated | Notes |
| -- | -- | -- |