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Re: More than meets the eye: Delta Orionis in Orion's belt

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On Thursday, November 12, 2015 at 5:49:48 PM UTC-8, Sam Wormley wrote:
> More than meets the eye: Delta Orionis in Orion's belt
> > http://phys.org/news/2015-11-eye-delta-orionis-orion-belt.html
> 
> > One of the most recognizable constellations in the sky is Orion, the
> > Hunter. Among Orion's best-known features is the "belt," consisting
> > of three bright stars in a line, each of which can be seen without a
> > telescope.
> >
> > The westernmost star in Orion's belt is known officially as Delta
> > Orionis. (Since it has been observed for centuries by sky-watchers
> > around the world, it also goes by many other names in various
> > cultures, like "Mintaka.") Modern astronomers know that Delta Orionis
> > is not simply one single star, but rather it is a complex multiple
> > star system.
> >
> > Delta Orionis is a small stellar group with three components and five
> > stars in total: Delta Ori A, Delta Ori B, and Delta Ori C. Both Delta
> > Ori B and Delta Ori C are single stars and may give off small amounts
> > of X-rays. Delta Ori A, on the other hand, has been detected as a
> > strong X-ray source and is itself a triple star system as shown in
> > the artist's illustration.
> >
> > In Delta Ori A, two closely separated stars orbit around each other
> > every 5.7 days, while a third star orbits this pair with a period of
> > over 400 years. The more massive, or primary, star in the
> > closely-separated stellar pair weighs about 25 times the mass of the
> > Sun, whereas the less massive, or secondary star, weighs about 10
> > times the mass of the Sun.
> >
> > The chance alignment of this pair of stars allows one star to pass in
> > front of the other during every orbit from the vantage point of
> > Earth. This special class of star system is known as an "eclipsing
> > binary," and it gives astronomers a direct way to measure the mass
> > and size of the stars.
> 
> 
> -- 
> 
> sci.physics is an unmoderated newsgroup dedicated
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> community, and physics-related social issues.

Actually, Sam, all (3) of the Belt Stars, Alnilam, Alnitak, and Mintaka, are at least double stars. For me, Zeta Orionis (Alnilam) is the most interesting, because it is a triple star and is immediately adjacent to the Flame Nebula (aka Tank Track Nebula), a wondrous sight in a telescope of almost any size.

\Paul A

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More than meets the eye: Delta Orionis in Orion's belt Sam Wormley <swormley1@gmail.com> - 2015-11-12 19:49 -0600
  Re: More than meets the eye: Delta Orionis in Orion's belt pnalsing@gmail.com - 2015-11-12 18:23 -0800
    Re: More than meets the eye: Delta Orionis in Orion's belt Sam Wormley <swormley1@gmail.com> - 2015-11-12 20:31 -0600
    Re: More than meets the eye: Delta Orionis in Orion's belt Fabian Russell <root@localhost.localdomain> - 2015-11-13 04:26 +0000
      Re: More than meets the eye: Delta Orionis in Orion's belt pnalsing@gmail.com - 2015-11-12 20:43 -0800
      Re: More than meets the eye: Delta Orionis in Orion's belt jimp@specsol.spam.sux.com - 2015-11-13 04:43 +0000
  Re: More than meets the eye: Delta Orionis in Orion's belt Double-A <double-a3@hush.com> - 2015-11-13 14:06 -0800
    Re: More than meets the eye: Delta Orionis in Orion's belt pnalsing@gmail.com - 2015-11-13 20:16 -0800

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