Sky and Telescope - June 2015 - 56

OBSERVING

Deep-Sky Wonders

A Heaven Full of Stars
Split the Serpent's star systems into their colorful components.
Alone in the night
On a dark hill
With pines around me
Spicy and still,

he described the stars as "extremely unequal." The large
magnitude diﬀerence begs a higher magniﬁcation than
you might otherwise expect from the generous separation of 31″ between the stars. Nonetheless, the pair
shows quite well through my 130-mm refractor at 48×,
with the 10.0-magnitude companion west of its 3.7-magnitude primary. A third member (C) shares the ﬁeld of
view, lying a spacious 3.3′ south-southwest.
Far removed from the AB pair, component C may
seem an unlikely companion. But on his website, Stars,
(stars.astro.illinois.edu/sow/sowlist.html), astronomer and
author Jim Kaler explains that these three stars keep pace
with one another as they move through space. With Beta
155 light-years away from us, Kaler calculates that the C
star is separated from the AB duo by at least 9,500 times
the distance between the Earth and Sun, and it would take
more than a half million years to orbit them once.
If this isn't impressive enough, consider component
D. In a 2011 paper in the Astrophysical Journal Supplement
Series, Ed J. Shaya and Rob P. Olling (University of Maryland) explain how they determined that some very wide
star pairs "are either presently bound or were previously
bound." Beta Serpentis AD forms one of these pairs.
Through the 130-mm scope and a wide-angle eyepiece giving 117×, I can ﬁt star D in the ﬁeld of view with
the other components. This also reveals that D itself is a
fairly close pair. The brighter star shines at magnitude
8.2, and its 10.7-magnitude attendant sits north-northwest. The D stars lie a whopping 27.4′ west-southwest of

And a heaven full of stars
Over my head,
White and topaz
And misty red;
Myriads with beating
Hearts of ﬁre
That aeons
Cannot vex or tire;
Up the dome of heaven
Like a great hill,
I watch them marching
Stately and still.
And I know that I
Am honored to be
Witness
Of so much majesty.
- Sarah Teasdale, Stars, 1920

June 2015 sky & telescope

29 Ser

POSS-II / STSCI / CALTECH / PALOMAR OBSERVATORY

Although the starry sky is one of our great loves, most
amateur astronomers don't think of stars as proper deepsky objects. But why not? They certainly reside beyond
the shallow sky (our solar ystem), and they're fascinating
objects in their own right. For some remarkable stars
that are now well-placed in our sky, let's visit Serpens
Caput, the Serpent's Head. We might picture this celestial serpent as a speckled king snake, ﬂecked with small
stars and inhabiting a regal place in the lofty heavens.
Unlike our Sun, most stars dwell in multiple star
systems, making them the most popular stars pursued by skygazers. Multiple stars come in a variety of
colors, separations, and magnitudes that heighten their
allure. What better place to start this month's tour than
the incredible system Beta (β) Serpentis, a probable
β
quintuplet! And all ﬁve components are visible through
a fairly small telescope.
In 1781 the famous observer William Herschel discovered the closest companion (B) to Beta Serpentis A, and

Beta Serpentis A

Beta Ser C

http://stars.astro.illinois.edu/sow/sowlist.html

Sky and Telescope - June 2015

Table of Contents for the Digital Edition of Sky and Telescope - June 2015