Brontes, Steropes and Arges:  The First Cyclopes

Of all the mythological races, the Cyclopes were among the most readily identifiable, though, ironically, the most misunderstood.    Afflicted with particularly hideous countenances, in which a single eye protruded from disfigured foreheads, the Cyclopes were generally less monstrous in character than they were in appearance.   We divide the Cyclopes into two generations, the first of which concerns us today. The first generation was sired by the original couple: Gaia, the Earth mother, and Ouranos, the Sky Father.     This generation consisted of three brothers:  Brontes, the "Thunder," Steropes, "Lightning Flash," and Arges "Sky brightness."      They developed the craft of metallurgy, and through their prodigious skill fashioned Zeus' thunderbolts, Posideon's trident, Hades' helmet of enveloping darkness, and a vast assortment of less noteworthy, but still brilliantly fashioned, devices. As was true with their siblings, such as the Titans and Hecatonchires, their father detested them, as he feared that they would all conspire to achieve his overthrow.    Ouranos therefore imprisoned them deep within Gaia, where they couldn't cause any trouble.   All of Ouranos' children were liberated after Cronos, with the aid of Gaia, castrated his father with a scythe and caused him to ascend from Gaia to form the sky.      As Cronos also feared the powerful Cyclopes, their freedom was short-lived.    Cronos consigned them to Tartarus, the punitive region with the Underworld.     Zeus, Cronos'  son,  eventually freed the Cyclopes,  as he required their assistance to defeat the Titans.  For their part, the Cyclopes were delighted to assist their liberator in destroying the Titan who had relegated them to Hell's deepest pit.     After the Titans fell and the gods exerted dominion over the Universe, Zeus permitted the Cyclopes to reside on Olympus, where they served dutifully as both Zeus' craftsmen and teachers to Hephaestus, god of fires, forges and furnaces. For his part, Zeus was equally delighted to have the Cyclopes on his side. It was said that Zeus' thunderbolts were as hot as the fiercest flame, swifter than the fastest winds and deadlier than an entire army.    The Cyclopes accumulated a store of these bolts, which the winged horse Pegasus fetched for Zeus whenever the occasion arose.   On one such occasion, Apollo's son, the divinely gifted healer Asciepius (the constellation Ophiuchus), resurrected Orion after Scorpius killed him with a lethal sting.   At Hades behest, Zeus struck Asciepus down with a thunderbolt. Enraged by Zeus' actions, but unable to avenge his son's death on Zeus, himself, Apollo slew all three Cyclopes brothers for they had crafted the weapon that killed his son.   Still indebted to the Cyclopes for their dutiful service, and aware that they had already experienced Tartarus's terrors in life, Zeus allowed them  to remain on Earth as phantoms dwelling within Mt Aetna.  The smoke constantly billowing out of Mount Aetna is said to still issue from their forges. Though the Cyclopes, now forever tethered to Earth, are not amongst the night sky's characters, they do lurk in the background. Every so often one might notice the spasms of heat lightning on the horizon: evidence of their continued presence and ceaseless labours.

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2020-2021:  VIII

THE DAILY ASTRONOMER
Thursday, September 10, 2020

Remote Planetarium 86:   Stellar Streams

Let us begin today by looking at traditional depiction of the Milky Way Galaxy:

A perfectly symmetrical, elegantly designed barred spiral galaxy as seen "face-on," at least in our imagination.    Our Sun, incidentally, resides along the "Orion Spur" a minor arm approximately 23,000 light years from the galactic nucleus.  From this vantagepoint, it's a mere spark within the Milky Way's vast sheaths of light.        Our continued cosmic exploration has brought us here: to regard the galaxy as a whole entity.   A series of spiral arms curling around a central bar containing a supermassive black hole.     Within and around those arms, literally billions of stars along with equal or even a greater number of planets.    Add to all this the vast gas dust stores concentrated along the galactic disk.     A churning, rotating amalgam of stars, planets, stellar remnants, and nebulae all composing our home galaxy.      However, that portrait is insufficient.    Let us now look at the galaxy again, this time with features we haven't yet discussed:

Stellar streams.

Not only are stars confined to the spiral arms.  They also comprise many of the elongated stellar streams that wrap around the galaxy.   Today we focus on these little known features of our galaxy.        What are they?  How did they form?  How long will they persist?

As their name suggests, they are literally streams of stars that can stretch up to more than one million light years from end to end.  These ends curl around the Milky Way Galaxy as we can observe in the above image.    Although they almost always consist of stars, one of the most massive examples, "The Magellanic Stream" is composed primarily of hydrogen gas stripped away from the Large and Small Magellanic Cloud,  satellite galaxies to the Milky Way.   This gas extends for more than one million light years.  So, too, does the largest stellar stream, one named "The Sagittarius Stream."      This stream consists of stars stripped away from the Sagittarius Dwarf Spheroidal Galaxy.   Approximately 10,000 light years in diameter, the Sagittarius Dwarf Spheroidal Galaxy is 400 million times more massive than the Sun.     

Sagittarius Dwarf Spheroidal Galaxy

A satellite galaxy to the Milky Way, the Sagittarius Dwarf Spheroidal Galaxy is due to be slowly absorbed by our home galaxy over the next one billion years.   Galactic tidal forces will continue to wick stars away from the dwarf galaxy as it passes above, below and through the galactic plane.

Other  examples of stellar streams include:

• The Helmi Stream         10-100 million solar masses.   The remnants of a defunct dwarf galaxy, this stream consists of many loops wrapping around the Milky Way Galaxy.  It is named for Amina Hemli (1970 - ), the Argentine astronomer who discovered it in 1999.  
• The Palomar 5 Stream     The stars within this stream originate in the Palomar 5 Globular Cluster.  This stream extends for only about 30,000 light years and its combined mass is merely 5000 times that of the Sun.
• Fimbulthal Stream     Named for an primordial river in Norse mythology, this stream consists of about 300 stars stripped away from Omicron Centauri, the largest globular cluster in the Milky Way.   With an estimated mass slightly greater than 300 solar masses, this stream was only discovered in 2019 in the GAIA DR 2 data.  Launched by the European Space Agency, GAIA's aim is to track the motions of more than one billion stars within the Milky Way Galaxy.

Gaia probe

The presence of such stellar streams remind us that the Milky Way Galaxy is hardly stagnant.    At this moment, the galaxy is cannibalizing nearby dwarf galaxies and drawing stars out of others.        In so doing, the Milky Way is gradually but inexorably increasing its stellar population.    Eventually, as we'll learn next week, the Milky Way will eventually merge with the Andromeda Galaxy to create a mega galaxy consisting of more than one trillion stars.     For now, however, the Milky Way is nibbling away at satellite galaxies: a process that will continue for billions of years.      

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