48 AUSTRALIAN SKY & TELESCOPE APRIL 2016
Celestial Calendar
C
arina contains many double
stars both within and
beyond the Milky Way that
passes through it. A number of
them were found by Carl Rumker,
who was brought to Australia by
Governor Brisbane, when he set up
the first significant observatory in
Australia at Parramatta in 1822.
The first of our Rumker doubles,
RMK 8 is about 3.5 degrees south-
southwest of 2nd-magnitude Epsilon
(ε) Carinae. The stars, of 5th and 7th
magnitude, have a similar separation
to Alpha Crucis, just under 4". An
80-mm telescope will show them
nicely. In the field northeast is the
wide, dim pair HJ 4077. RMK 8 is
a beautiful double, the stars pale
yellow and deep yellow.
Just west of Epsilon Car is HJ
4084 , discovered by John Herschel
in the 1830s. The bright yellow
primary has a double companion
fairly wide southeast, which showed
nicely as a little 10th-magnitude pair
with my 140-mm refractor at 114x.
Small telescopes might only show
this pair as a single star.A dozen doubles in Carina
One of Australia’s earliest astronomers discovered numerous double stars. ROSS GOULD
Some 3 degrees northeast from
Epsilon, beyond e-1 and e-2 Carinae,
is the attractive pair HJ 4130. The
6th- and 8th-magnitude stars are
pale yellow and orange (Hartung
says “reddish” of the lesser star),
and 4” apart, so 80-mm scopes
will show it well. A long-period
binary, it has slightly widened with
some increase in angle since John
Herschel’s 1835 discovery.
South and just east at 1.5-degrees
from HJ 4130 is RMK 9. The 7th-
magnitude stars are an easy split;
even 60 mm will show this white
pair. It’s a distant object, roughly
800 light-years from us. There are
two wide-field star companions of
10th and 11th magnitude, north and
southwest of the bright pair.
Moving eastwards, our next
double is R 123, an 1873 discovery
by Henry Russell, 19th century
director of Sydney Observatory.
Both stars are around magnitude
7.5 and white, nearly 2” apart, a
little closer than at discovery. My
18-cm refractor showed a neat split
at 100x. For a 60-mm telescope,this is a Dawes’ Limit split.
Moving well south we find
the beautiful showpiece double
Upsilon (υ) Carinae, another
Rumker discovery (RMK 11). The
3rd- and 6th-magnitude stars are
an easy 5” apart, and the brightness
contrast makes it a superb object.
Through various telescopes from
14- to 21-cm I’ve found a power of
100x sufficient. Common proper
motions suggest a binary. It’s
shown no definite change since the
first measure, by John Herschel
in 1836, when he also noted the
little pair 5’ to the southeast; this
is HJ 4252; slightly unequal 9th-
magnitude stars an easy 12” apart.
Another of Rumker’s pairs is
RMK 12, 4 degrees south and just
east from RMK 11. Not as bright or
as striking at magnitudes 7 and 9,
it’s nevertheless a pleasant sight,
the white stars 9” apart and clear
with a 60-mm scope.
Finally, HJ 4295 is 1.3 degrees
east-northeast from RMK 12. This
6th-magnitude star has a fairly wide
mag-11.5 companion noticed by John
Herschel. The main interest is the
bright pale yellow star, because 60
years after Herschel it was found by
Robert Innes with a 16-cm refractor
to be a close pair of 6.5-magnitude
stars, I 13. When I observed I 13
with a 15-cm refractor the star was
not single but elongated at 270x,
becoming more obvious at 375x. The
most recent measure was 0.65” in
2010, so a 20-cm telescope should
provide a barely separated pair at
high power in good seeing. I 13 is
nearly 700 light-years from us.Ross Gould can be reached at
[email protected]Star Name R. A. Dec. Magnitudes Separation PositionAngle MeasureDate of Spectrum
RMK 8 08 15.3 -62°55 5.3, 7.6 3.6" 068 2010 A2
HJ 4077 08h 15.9m -62° 52 9.2, 10.6 18.6" 305 2000
HJ 4084 08 h17.9m -59° 10 AB 6.5, 9.8 42.2" 150 2000 F5V, A2V
" " " BC 9.8, 9.9 3.1" 087 2000
HJ 4130 08 h40.7m -57° 33 6.5, 8.3 4.0" 240 1998 A4V, F7V
RMK 9 08 h45.1m -58° 43 6.9, 6.9 4.2" 292 2010 B7III
R 123 09 h33.3m -57° 58 7.5, 7.6 1.9" 033 2014 B8III
Upsilon (RMK 11) 09 h47.1m -65° 04 3.0, 6.0 5.0" 126 2010 A8Ib
HJ 4252 09 h47.8m -65° 07 8.7, 9.1 12.3" 303 2000 B8V
RMK 12 09 h55.1m -69° 11 6.9, 8.9 9.2" 213 2000 B9V
I13 10 h09.5m -68° 41 AB 6.5, 6.6 0.65" 104 2010 A0IV
HJ 4295 " " AB,C 6.1, 11.5 25.8" 040 2000Rumker’s doubles in central Carina
Data from the Washington Double Star Catalog.