Sky and Telescope - August 2017 - 25

Nu Draconis

39 Draconis

Omicron Draconis

Rho Draconis

16, 17 Draconis

46 Draconis

64, 65 Draconis

Kappa Cephei

64 Dra
16 Dra
17 Dra

1: SCOT T M ACNEILL; 2 & 3: MIK E WOOD / WEBB DEEP-SK Y SOCIE T Y;
5: BL A K E N A NCA RROW; 4, 6, 7, 8, 9: POSS-II / STSCI / CA LTECH /
PA LO MAR OBSERVATORY

6, 7

65 Dra

Now zoom 10° northeast to locate 64 Draconis. It's not
a true double, but it does make a very wide (748″) optical
pair with nearby 65 Draconis. At 5th and 6th magnitudes,
64 and 65 Draconis should be visible, and splittable, with
the naked eye - can you do it? 65 Draconis is itself an optical double with the considerably dimmer HD 190696. Try
comparing the brightnesses of 65 Draconis and 39 Draconis.
Their companions are equally dim at magnitude 7.9, and at
comparable separations, but 65 Draconis is over one magnitude dimmer than 39 Draconis.

About 3° north of the pentagon formed by 64 Draconis and its companions is bright Rho (ρ) Draconis. Any
binoculars should show a 6th-magnitude optical companion
about ¼° northeast of Rho. You'll need 10× or 15× binos,
probably mounted, to pick out the 9th- and 10th-magnitude
outriders lurking about 150″ to either side of the primary.
Just about 10° due north of Rho you'll ﬁnd the wide
optical double Kappa (κ) Cephei. I'm cheating a bit here,
since Kappa isn't actually in Draco, but it's on the way
and it's pretty, so there's nothing to lose by looking. With

1 Scott MacNeill of Frosty Drew
Observatory, Charlestown, Rhode
Island, captured this image of
Draco's penetrating "eyes" with
fifty 30-second exposures through
a Canon 60D camera mounted
on a 6-inch Ritchey-Chrétien
telescope.

3 The primary of 39 Draconis is a
main-sequence A-type dwarf star,
while the secondary is an F-type.
Higher magnifications may reveal a
bit of color in the secondary, but in
binoculars both will appear white,
with the 5th-magnitude primary
shining more brightly.

5 Two G-type main-sequence
stars compose Omicron Draconis.
Observers usually perceive the
primary as a golden or orange yellow, with the secondary described
as lilac or turquoise. You'll need
to break out big binos to split this
one, as the components are separated by a mere 37.3″.

2 The view through a 200-mm
(8-inch) Maksutov-Cassegrain
telescope at 222× revealed a hint
of blue to the otherwise white B9
dwarf stars, 16 and 17 Draconis.
Most images and sketches of
double stars are made with telescopes, rather than binoculars,
so don't be disappointed if your
view doesn't match the resolution of published images. Use the
images here to judge the relative
brightness and position angle of
the binary components.

4 The 5th-magnitude star 46
Draconis is a blue-white mainsequence A-type. The optical
companions are both K-type dwarf
stars. The 8th-magnitude star HD
238925 lies northwest of 46 Dra
while 7th-magnitude HD 173580
lies almost the same distance from
46 Dra to the southeast.

6, 7 The M-type star 64 Draconis
isn't a true double, but forms a
wide optical double with 65 Draconis. Although many M-class stars
are quite dim, M1 super giants
like 64 Dra should be visible to the
naked eye. 65 Draconis is G-type
main-sequence star.

8 Look for the 6th-magnitude optical companion to Rho Draconis
about ¼° northeast of the primary.
If you have big binos on your
tripod, try for the 9th- and 10thmagnitude companions northwest
and southeast of Rho.
9 Wander north of Rho Draconis
to find the B9-class double star,
Kappa Cephei.

Are you ready for further adventures?
Find more Draco double stars at https://is.gd/DracoDoubles.
s k y a n d t e l e s c o p e .c o m

* AUGUST 2017

https://www.is.gd/DracoDoubles http://www.skyandtelescope.com

Sky and Telescope - August 2017

Table of Contents for the Digital Edition of Sky and Telescope - August 2017