Sky & Telescope - December 2021 - 59

MASIL IMAGING TEAM
TWINKLE TWINKLE SINGLE STAR
Using this annotated image, find your way
to Andromeda's brightest supergiant star,
J004406.32+420131.3, by starting at NGC 205,
one of its satellite galaxies (right). From there,
use the helpful asterism (labeled) to navigate
to your destination. The prominent star near
the supergiant is a 9th-magnitude Milky Way
foreground star.
J004406.32+420131.3
are " probably field stars. " As for 77 and
119, despite their location near the cluster's
center, he considered them " a tossup "
because of the color discrepancy.
That left 60 as the only likely member
I tentatively saw. Part of me felt
crushed, but at the same time I was
happy to get a definitive answer. As an
observer I'd rather wince and get it right
than pretend otherwise. But the story
doesn't end there. After all, NGC 206
isn't the only game in town.
Sweet Success!
M31 is home to a number of luminous
blue and yellow supergiants,
including the yellow supergiant
J004406.32+420131.3, also designated
M31-004406.32. The paper titled " Yellow
Supergiants in the Andromeda Galaxy
(M31) " by Maria Drout (currently
at the University of Toronto) and her
collaborators lists the star as belonging
to M31. With a magnitude of 15.6, it's
squarely within range of a 12.5-inch or
larger instrument.
One especially transparent morning
in October 2020, I plotted the star's
position on a photograph and starhopped
to its location with my 15-inch.
Though quite faint, I found it quickly
using magnifications of 357× and 428×.
Under ideal conditions even a 10-inch
telescope should snag this star.
It appeared like any faint star, but
of course it wasn't just any star. Good
gosh, I was looking at a supersized sun
in another galaxy, and it didn't have to
explode as a supernova to be visible! I
took in the scene and tried to imagine
the gulf of time and space that separated
my eye and this tiny jewel.
John Martin, associate professor at
the University of Illinois (Springfield),
worked with colleagues on a project that
cataloged the most luminous stars in
M31 and M33. It proved an invaluable
NGC 205
Stars Brighter than Magnitude 17 in M31
Mag(v)
Target
15.6
16.0
16.2
16.3
16.4
16.6
16.7
16.7
16.8
16.8
16.8
16.9
While the star names
listed at right look
cumbersome, they're
useful because they
actually describe the
stars' locations. For
example, you'll find
J004406.32+420131.3 at
right ascension 00h 44m
06.32s and declination
+42° 01′ 31.3″. You can
use an online atlas such
as Aladin Lite (https://
is.gd/AladinLite) to locate
these targets using
these designations. Bob
would love to hear from
you at nightsky55@
gmail.com if you spot of
any of the targets listed!
J-designation
M31-004406.32 J004406.32+420131.3
AF And*
J004333.09+411210.4
M31-004507.65 J004507.65+413740.8
M31-004034.82 J004034.82+401825.5
M31-004247.30
M31-004424.21
J004247.30+414451.0
J004424.21+412116.0
M31-004434.65 J004434.64+412503.5
M31-004518.76 J004518.76+413630.7
M31-004021.21
J004021.21+403117.1
M31-004526.62* J004526.62+415006.3
Var A1*
M31-004129.31
J004450.54+413037.7
J004129.31+405102.9
* Indicates Luminous Blue Variable. Target names are from the online
catalog of luminous stars listed below.
resource in my star search. During our
email exchange Martin provided me
with an updated list of stars brighter
than 17th magnitude for amateurs
seeking some of M31's " softer " targets
(see the sidebar above). I plan to work
my way through that list in hopes of
adding a second or third Andromedan
gem to my collection.
When I was a kid, I never imagined
that one day I would gaze upon individual
stars in the Andromeda Galaxy.
But thanks to the work of professional
astronomers, amateurs are privy to the
deepest recesses of these unimaginably
remote objects.
¢Contributing Editor BOB KING likes
to meet face-to-face with everything
he's read about in astronomy books.
He wishes to thank Scott Harrington,
Stephen Odewahn, and John Martin for
their assistance during the preparation of
this story.
FURTHER READING: You'll find Stephen
Odewahn's article at https://is.gd/Odewahn
and Maria Drout and colleagues' paper
on yellow supergiants at https://is.gd/
Drout. Go to https://is.gd/LuminousStars
for the catalog of luminous stars in M31
and M33 and to https://is.gd/M31_M33_
info for detailed information and photos.
sk yand tele scope .o r g * DECEMBER 2021 59
https://www.is.gd/AladinLite https://www.is.gd/AladinLite https://www.is.gd/Odewahn https://www.is.gd/Odewahn https://www.is.gd/Drout https://www.is.gd/Drout https://www.is.gd/LuminousStars https://www.is.gd/M31_M33_info https://www.is.gd/M31_M33_info http://Skyandtelescope.org
Sky & Telescope - December 2021

Table of Contents for the Digital Edition of Sky & Telescope - December 2021
