APOD: Pleiades to Hyades (2019 Dec 06)

[APOD Robot]

Pleiades to Hyades

Explanation: This cosmic vista stretches almost 20 degrees from top to bottom, across the dusty constellation Taurus. It begins at the Pleiades and ends at the Hyades, two star clusters recognized since antiquity in Earth's night sky. At top, the compact Pleiades star cluster is about 400 light-years away. The lovely grouping of young cluster stars shine through dusty clouds that scatter blue starlight. At bottom, the V-shaped Hyades cluster looks more spread out in comparison and lies much closer, 150 light-years away. The Hyades cluster stars seem anchored by bright Aldebaran, a red giant star with a yellowish appearance. But Aldebaran actually lies only 65 light-years distant and just by chance along the line of sight to the Hyades cluster. Faint and darkly obscuring dust clouds found near the edge of the Taurus Molecular Cloud are also evident throughout the celestial scene. The wide field of view includes the dark nebula Barnard 22 at left with youthful star T Tauri and Hind's variable nebula just above Aldebaran in the frame.

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[Ann]

I'm always very glad to see the Pleiades in an APOD! And seeing it in the same frame as the Hyades just underscores how special the Pleiades is.

For me as a color commentator, it is remarkable that the bright stars of the Pleiades are "all blue". At the Pleiades' age, at least 100 million years, and in view of the cluster's relatively high mass, we expect it to contain one or more red giants. So where did all the red giants go? Did they cast off their outer atmospheres, light up as ephemeral planetary nebulas, dissolve into empty space, and leave cooling white dwarfs behind? But if so, where are the white dwarfs of the Pleiades? I don't know of any. The all-blue color of the bright stars of the Pleiades is actually a mystery.

Not that I'm complaining!

Ann

Edit: The Pleiades does contain a white dwarf. Well, mystery solved, I guess!

[orin stepanek]

Today"s APOD; !

[sillyworm 2]

Aldebaran ,being a Red Giant,is it's future calling to be a supernova? Do we know how long after a star has shed it's mass and turns into a white dwarf that it will supernova? Does a white dwarf always eventually supernova?

[neufer]

• Man...that's a lot of dust

<<"Ulysses" is a poem in blank verse by the Victorian poet Alfred, Lord Tennyson (1809–1892), written in 1833. An oft-quoted poem, it is popularly used to illustrate the dramatic monologue form. Facing old age, mythical hero Ulysses describes his discontent and restlessness upon returning to his kingdom, Ithaca, after his far-ranging travels. Despite his reunion with his wife Penelope and son Telemachus, Ulysses yearns to explore again.

• It little profits that an idle king,
  By this still hearth, among these barren crags,
  Match'd with an aged wife, I mete and dole
  Unequal laws unto a savage race,
  That hoard, and sleep, and feed, and know not me.
  I cannot rest from travel: I will drink
  Life to the lees: All times I have enjoy'd
  Greatly, have suffer'd greatly, both with those
  That loved me, and alone, on shore, and when
  Thro' scudding drifts the rainy Hyades
  Vext the dim sea: I am become a name; >>

[Chris Peterson]

Aldebaran ,being a Red Giant,is it's future calling to be a supernova? Do we know how long after a star has shed it's mass and turns into a white dwarf that it will supernova? Does a white dwarf always eventually supernova?

A white dwarf is the end stage of stars with a mass less than about 10 solar masses. White dwarfs don't supernova on their own... although they can produce type 1a supernovas if they have a companion star that deposits enough material on them, raising their mass and starting a runaway fusion reaction in the interior. Such supernovas are very rare in comparison with the number of white dwarfs. That is, white dwarfs only very, very rarely supernova.

Aldebaran is a fairly low mass star, just slightly more massive than the Sun. It may have a companion, but that's not certain. Even if it does, it's unlikely to ever result in a supernova.

[sillyworm 2]

Thanks Chris...after posting I did look up info on that star.I just finished reading up on one very interesting site about Epsilon Eridani.What a fascinating star system! This star system deserves an APOD of it's own.

[neufer]

Thanks Chris...after posting I did look up info on that star.I just finished reading up on one very interesting site about Epsilon Eridani.What a fascinating star system! This star system deserves an APOD of it's own.

• https://apod.nasa.gov/apod/ap000807.html

[sillyworm 2]

Thanks Neufer! Let's hope some newer information soon comes to light.The site I found had illustrations of asteroid belts,etc.

[JimThomas]

I was about to quote the same reference. You beat me to it. No matter. I treasure that whole poem and carry it around in my mind at all times.
Great to encounter someone else who knows about it.

Tho' much is taken, much abides; and tho'
We are not now that strength which in old days
Moved earth and heaven, that which we are, we are;
One equal temper of heroic hearts,
Made weak by time and fate, but strong in will
To strive, to seek, to find, and not to yield.
— Alfred, Lord Tennyson [1809–1892]

[Boomer12k]

Stunning image of details of this vast vista...

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