60 ASTRONOMY • JANUARY 2020SECRET SKY
This month, we’ll
track down some
discoveries that
English astronomer John
Russell Hind (1823–1895)
made with the 7-inch f/18
Dollond refractor at
George Bishop’s South
Villa observatory in
L ondon’s Regent ’s Pa rk.
Almost all of his finds are
superlative objects, mean-
ing they’re either first
sightings or superb in
visual appearance — and
all are unusual.
We’ll begin with one of
the least targeted of Hind’s
discoveries, NGC 4125.
Hind happened upon this
10th-magnitude “tolerably bright” lens of light with a
“strong nuclear condensation” in January 1850,
although he was unaware of its true nature. What he
had discovered is a peculiar massive elliptical galaxy in
which evolved stars produced in a merger-triggered
burst of star formation are pumping large
amounts of gas and dust into the galaxy’s
interstellar medium. You’ ll find this 6' by 3'
hidden treasure about 5° southeast of Kappa
(κ) Draconis.Changing lights
Next up is the tricky NGC 1555 — a nebula
that varies in brightness, shape, and size
along with its luminary: the 1-million-year-
young variable star T Tauri, which f luctuates
between magnitude 8.5 and 13.5 with no
known period. Popularly known as Hind’s
Variable Nebula, NGC 1555 was the first of its type to
vary in size, shape, and brightness.
Using moderate-sized apertures, I (and many others)
had long searched for the nebula without success in past
decades. In 2016, however, I began reading reports from
observers who’d spotted the nebula through telescopes
as small as 6 inches. Finally, in July 2019, I spied its shy
glow through an 8-inch ref lector, with T Tauri glowing
around magnitude 10.5 and the nebula appearing as a
little f lirtatious skirt of diaphanous light less than 1' west
of the star. So, unless the winds of change choose to blow,
perhaps you’ ll have luck as well.On December 15, 1855, Hind encountered a previously
u ncha r ted 9 t h-ma g n it ude st a r i n G em i n i t hat he t hou g ht
was a nova. Now designated U Geminorum, this dwarf
nova — a cataclysmic binary system where a white dwarf
is accreting matter, usually from a red giant star — is the
prototype of its class and the first to be discovered.
Usually, U Gem rests around magnitude 14.5, but
every 100 days or so, it f lares — many times up to 8th
magnitude — in less than a day, before fading over the
cou rse of d ay s or week s. C atch i ng a n outbu rst may send
a t i ng le up you r spi ne. Cu r iou sly, H i nd ’s contempor a r y,
Norman Pogson, noted that the star takes on a “pale
bluish white tint when near maximum; never ruddy.”
When he observed the star at its first reappearance after
its discovery, he noted a “curious scintillation or twin-
kling” about the third day after maximum, “which could
not arise from atmospheric disturbances, as neighbour-
ing smaller stars were not similarly affected.”Crimson dynamo
Hind’s discovery most observed by amateur astrono-
mers is R Leporis. When Hind discovered this Mira-
t y pe va r iable st a r i n 18 45, he de sc r ibed it a s “re sembl i ng
a blood drop on the background of the sky.” Since then,
it has become known as Hind’s Crimson Star — a burn-
ing ember reminiscent of a red-hot coal that f luctuates
in brightness from a maximum magnitude of 5.5 to a
minimum of 12 over a period of roughly 427 days.
The luminary appears so red because its highly
evolved atmosphere is surrounded by a sooty shell
of carbon and carbon compounds. That
material makes R Leporis one of the reddest
stars visible.Queen’s rock
T h is mont h we a l so have a H i nd sola r s y stem
discovery on the rise in the east: main-belt
asteroid 12 Victoria, which Hind found in
September 1850. Named in honor of Queen
Victoria, it was the first asteroid to be named
after a living person. The roughly 75-mile-
wide (120 kilometers) rock orbits the Sun
with a period of 3.56 years.
It shines around 12th magnitude at the beginning of
January 2020 and one magnitude brighter toward
month’s end. You’ll find it in the constellation Sextans:
on January 1 at right ascension 10h17m51s and
declination –1°06'39"; on the 15th at R.A. 10h13m05s
and Dec. –1°32'44"; and on the 31st at R.A. 10h01m42s
and Dec. –1°19'02".
As always, send your comments to sjomeara31@
gmail.com.Some noteworthy finds by a noteworthy astronomer.
Hindsight
Hind’s Variable
Nebula (NGC 1555)
can be a tough catch
in a medium-sized
scope. East is up in
this image. ADAM BLOCK/
MOUNT LEMMON SKYCENTER/
UNIVERSITY OF ARIZONAUsually,
U Gem rests
around
magnitude
14.5, but
every 100
days or so,
it flares.BY STEPHEN
JAMES O’MEARA
Stephen is a globe-
trotting observer who
is always looking
for the next great
celestial event.BROWSE THE “SECRET SKY” ARCHIVE AT
http://www.Astronomy.com/OMeara