An Etymological Dictionary of Astronomy and Astrophysics
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The Scorpion. A large and impressive constellation in the → Zodiac, which lies between → Libra to the west and → Sagittarius to the east. Scorpius is located in the southern hemisphere near the center of the Milky Way at approximately 17h right ascension, -40° declination. The bright, red star → Antares marks the heart of the scorpion. The constellation contains deep sky objects such as the open clusters M6 and M7, and the globular clusters M4 and M80. Also in the southern end of the constellation there is the open star cluster NGC 6231. Abbreviation: Sco; genitive: Scorpii.

M.E., from O.Fr. scorpion, from L. scorpionem (nominative scorpio), from Gk. skorpios "a scorpion," from PIE base *(s)ker- "to cut," → shear. According to Gk. mythology, the constellation represents a giant scorpion sent forth by the earth-goddess Gaia to kill the giant Orion when he threatened to slay all the beasts of the earth. Orion and the Scorpion were afterward placed amongst the stars as a pair of constellations. The two opponents are never seen in the sky at the same time, for one constellation sets as the other rises. The scorpion's claws were originally formed by Libra.

Každom "scorpion," variants kajdom, gaždom literally "crooked tail," from Mid.Pers. gazdum literally "stinging tail," from gaz present stem of gazidan (also Mod.Pers.) "to sting, to bite" + dum, dumb (Mod.Pers. dom, domb) "tail;" Av. duma- "tail."

The first and the brightest X-ray source in the sky, after the Sun, discovered in 1962. Scorpius X-1 is a low-mass → X-ray binary consisting of a compact object like a → neutron star or a → black hole, and a low-mass stellar companion. The compact object has a mass of 1.4 → solar masses and the companion 0.42 solar masses. The orbital period is 18.9 hours, and the system lies at a distance of about 9,000 → light-years. The X-rays come from → accretion, where material from the companion overflows its → Roche lobe and spirals down onto the compact object. The luminosity results from the transformation of the falling material's → gravitational potential energy to heat by → viscosity in the → accretion disk.

Named such by the discoverers (Giacconi et al. 1962), because it was the first extrasolar → X-ray source of the sky detected in the constellation → Scorpius.

The nearest → OB association to the Sun. It contains several hundred stars, mostly → B stars which concentrate in the three subgroups: Upper Scorpius, Upper Centaurus Lupus, and Lower Centaurus Crux. Upper Scorpius is the youngest subgroup, Upper Centaurus Lupus the oldest subgroup of the association. Isochrone fitting to the Hertzsprung-Russell diagram indicates that the star formation occurred some 5-20 Myr ago. Based on data from the → Hipparcos catalog, it turns out that the Sco-Cen association lies at a distance of 118-145 → parsecs, with the exact value depending on the subgroup of the association. The Sco-Cen association is probably a member of the → Gould Belt (Preibisch & Mamajek, 2008, astro-ph/0809.0407).

→ Scorpius; → Centaurus; → association.