http://www.skyandtelescope.com.au 51by Sue French TARGETSLEPUS DRAWING: ETH-BIBLIOTHEK ZüRICH / ALTE UND SELTENE DRUCKE
W Johann Bayer’s 1603 celestial atlas
Uranometria contains 51 star charts engraved
by Alexander Mair, a German artist who,
like Bayer, lived in Augsburg. Mair based
his charts on woodcuts carved by Jacob de
Gheyn for Hugo Grotius’s edition of Aratus,
published in Leiden in 1600.O
n a warm summer’s evening
rich with brilliant stars, dim
Lepus, the Hare, shyly crouches
near Orion, hoping to be overlooked
by the mighty hunter. Among the stars
used to place the Hare’s image in the
sky, four of the faintest mark his ears
as seen on our image of Lepus from
Johann Bayer’s unprecedented 1603
atlas, Uranometria. They are ι, κ, λ and
ν, and around them lie the deep sky
wonders for this month’s sky tour. As
lagomorph lovers are fond of saying, it’s
all about the ears.
The jumping-off point for our foray
is Kappa (κ) Leporis, which itself is
worth a look along the way. Kappa is a
double system composed of two white
stars. Their magnitude difference and
close quarters beg high magnification
for a good look, somewhere around
200 ×, depending largely on your
viewing conditions. The fainter star sits
north of its primary.
About three-fifths of the way from
Kappa Leporis to 60 Eridani we encounter
R Leporis, also known as Hind’s Crimson
Star. Its striking colour was first noted
by John Russell Hind, who came across it
while comet-sweeping in October 1845.He wrote, “At that time it was of the most
intense crimson, resembling a blood-drop
on the black ground of the sky”. In a
letter he penned to William Henry Smyth
in 1850, Hind avers, “This is by far the
most deeply-coloured of any that I have
yet seen, and in striking contrast with
a beautifully white star preceding it one
minute.”It’s all about the ears
A few short hops lead from a carbon star to a planetary nebula
and a pair of interacting galaxies.R Leporis is a carbon star, or more
specifically, a cool red giant with
carbon molecules in its atmosphere.
This carbon soot scatters what little
blue light the star’s photosphere emits,
so only ruddy hues make their way to
the observer’s eye. Most carbon stars
are variable, and R Lep pulsates with
a period of about 445 days and an
overall magnitude range of 5.5 to 11.7.
A carbon star looks less red to your eye
when it’s bright. While visiting Hind’s
Crimson Star, compare it with Hind’s
“beautifully white star,” 14.6′ (one
minute of right ascension) west.
Now we’ll move on to the planetary
nebula IC 418, which sits at the sharp
end of a 1.9° long, eastward-pointing
isosceles triangle that it forms with
two of Lepus’ ear stars — Lambda
(λ) and Nu (ν). Amateur astronomer
Vic Menard nicknamed IC 418 the
Raspberry, which refers to the unusual
colour some observers see in this
nebula. Through my 130-mm refractor
at 23×, I see the bright central star19571888
18891954IC 41858596064ιμλν8αLEPUSERIDANUSR5 h 00 m–12°5 h 30 m^5 h^20 m^5 h^10 m^4 h^50 m–14°–16°–18°Star magnitudes546
7
8