The Orion Nebula, the Pleiades, and the Planet from Star Trek

Observatory / Course Archives / ASTR 110 Fall 2019 / Rop

  • Orion Nebula
  • The Pleiades Star Cluster (Seven Sisters)
  • HD 26965 A (40 Eridani A; Vulcan)

Orion Nebula

The Orion Nebula is an emission nebula at the heart of the Orion constellation, at a distance of 1,500 light-years away. Nebulae are clouds of dust and gas in interstellar space; the birthplaces of stars. Nebulas range in size: some are mere millions of miles across, others are hundreds of light-years wide. The Orion Nebula is thought to be 25 light-years wide. The Nebula, as the closest nebula to Earth, is near enough to make it the perfect studying ground for the formation of stars; most stages of a star's life can be seen within. Astronomers estimate a minumum of 1000 younger stars in the nebula, which is the brightest point in the sword of Orion, The Hunter. The brightness is due to the shining of four massive stars in the center. These are collectively called the Trapezium.

This image is a composite image of the visible and ultraviolet light pictures taken by the Hubble Space Telescope, and the infrared view from Spitzer. The clouds of green, seen with UV and visible light, reveal the presence of ionized hydrogen and sulfer gas. The red and orange clouds are carbon-rich molecules that are illuminated by the Trapezium. The stellar winds from these massive stars at the nebula's interior have blown most of the gas and dust away from the interior, creating a cavity; and thus, a clear view into the nebula.These winds are responsible for the dips and grooves noticeable in the nebula.

The Orion Nebula is visible to the naked eye, yet there is no mention of it in any ancient texts. This has led to speculation that the luminosity may have risen fairly recently, perhaps due to new star formation. The Nebula was first documented in writing 1610 by a French astronomer.

The Pleiades (Seven Sisters)

The Pleiades star cluster, also known as the Seven Sisters, can be seen from almost anywhere on the globe. While visible (and prominent) to the naked eye, it is actually made up of hundreds of stars, of which we can only see the brightest. They were likely formed 100 million years ago, making them very young stars. Their blue/white color is indicative of their age; high heat and energy output is characteristic of young stars, and produces a blue color. The blue filaments around some of them are a result of the blue light reflecting off of grains of dust on its way to Earth.

The Pleiades are about 425 light years away, located against the backdrop of the constellation of Taurusand nearby the constellation of Orion. In Greek Myth, from where they get their name, the Pleiades are the seven daughters of Atlas. Running from the hunter Orion, the sisters beg Zeus to save them. Zeus does, by turning them into stars. Upon Orion's death, he is said to have become a constellation, to forever be chasing the lovely Pleiades through the sky.

Many ancient cultures used the Pleiades for marking important points in their calendar. For example, in Ancient Greece, and other Mediterranean civilizations, the day of their first appearance in the sky before sunrise marked the beginning of the sailing season. The modern holiday of Halloween partly comes from an ancient Druid myth that the veil between the dead and the living was at its thinnest when the Pleiades reach their highest point at midnight-- which happens around October 31st each year. All over the globe the Pleiades are found in ancient myth.

HD 26965 A (40 Eridani A; Vulcan)

HD 26965 A was the first exoplanet ("A") discovered around its star (HD 26965); thus, its name. It's star is about 16 light years away, and can be seen with the naked eye. The star shares its system with two other stars; all three of these would be visible from the exoplanet's surface. In this artist's rendition, only one star is visible.

The exoplanet has an orbital period of about 42 days, and is nearly twice the size of Earth. Unfortunately, it seems to be located too near its star for it to retain water, making it unsuitable for life. Not much else is known about the exoplanet's surface or structure. HD 26965 A is the first super-Earth discovered by the Dharma Planet Survey. It was recently discovered with the radial velocity technique, which uses the Doppler effect.

Fans of Star Trek have another reason for being excited about this exoplanet. HD 26965 is the star which was confirmed by Gene Roddenberry (the creator of Star Trek), in participation with the Harvard-Smithsonian Center for Astrophysics, to be the planet Vulcan's host star. Vulcan is home to one of Star Trek's most beloved characters; Spock. In the Star Trek lexicon, this host star, HD 26965 is dubbed 40 Eridani A. The possibility of a planet orbiting 40 Eridani A has long a subject of consideration and debate by Star Trek fans. Now, with the discovery of this exoplanet, science fiction has become a little more real.

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