Sky and Telescope - February 2017 - 54

FEBRUARY 2017 OBSERVING
Deep-Sky Wonders by Sue French

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.

-12°

1888

ι

ν
IC 418

1954
-14°
1957

Star magnitudes

1889

λ

64

κ

8

4
5
6
7
8

ERIDANUS

LEPUS

R

μ

-16°

60

59
58

-18°

α
5h 30m

54

5h 20m

5h 10m

F E B R U A R Y 2 0 1 7 * SK Y & TELESCOPE

5h 00m

4h 50m

S Johann Bayer's 1603 celestial atlas Uranometria contains 51 star charts engraved
by
Mair,
German artist
like
b Alexander
Al
d M
i aG
ti t who,
h lik
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.

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.
It reached minimum light last October, and maximum is expected in late
May or early June. This gives us a good
observing window with R Lep likely to
be between magnitude 8 and 9 during February, if the last cycle is any
indication. The star should be bright
enough to find without difficulty, yet
dim enough to show off its fiery hue.
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). Florida amateur Vic Menard
nicknamed IC 418 the Raspberry, which
refers to the unusual color some observ-

LEPUS DR AWING: E TH-BIBLIOTHEK ZüRICH / A LTE UND SELTENE DRUCK E

O

for a good look, somewhere
re around
200×, depending largely on
n your viewing conditions. The fainterr star sits atop
(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 color 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."

n a cold winter's evening rich with
brilliant stars, dim Lepus, the Hare,
shyly crouches beneath 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



Sky and Telescope - February 2017

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

Contents
Sky and Telescope - February 2017 - Cover1
Sky and Telescope - February 2017 - Cover2
Sky and Telescope - February 2017 - 1
Sky and Telescope - February 2017 - Contents
Sky and Telescope - February 2017 - 3
Sky and Telescope - February 2017 - 4
Sky and Telescope - February 2017 - 5
Sky and Telescope - February 2017 - 6
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