Sky and Telescope - February 2016 - 52

OBSERVING

Deep-Sky Wonders

Jeremy Perez sketched
the A, B, and C components of Gamma Leporis as viewed through
his 6-inch Newtonian
reﬂector at 240×. The
colorful components
split easily even in
smaller scopes.

Sun-yellow star with a
brick red companion; both
colors are seen vividly" (see also
S&T: Nov. 2015, p. 28). What hues do you see?
The suns of Gamma Leporis have kept pace with one
another as they moved through space over the last two
centuries, indicating that they are probably true companions. Their 95.0″ apparent separation shows that their true
separation is at least 848 times the Earth-Sun distance.
Taking the stars' masses into account, this implies a
minimum orbital period of 17,000 years. Gamma is a near
neighbor to our Sun, only 29 light-years away from us.
Our next object is NGC 2017, which has been variously
called an open cluster, a possible open-cluster remnant,
an asterism, and a multiple star. Sources claiming that it's
a known cluster also mention infrared and radio emission
from the object, which makes it clear that this is an identiﬁcation error. The mistake springs from a mistyped title
in the SAO/NASA Astrophysics Data System, an internet
portal for journal papers in astronomy and physics (http://
ads.harvard.edu/). The actual paper is about NGC 2071, a
star-forming region in Orion. NGC 2017 is listed as a multiple star with nine components in the online Washington
Double Star Catalog (WDS), but physical relationships
among the stars are undetermined.

Whatever its true nature, NGC 2017 is a pretty ﬁnd
through a telescope. When John Herschel discovered
it in 1835, he sketched the aggregation and called it "an
elegant group of 6 large stars." My 105-mm refractor
reveals four stars at 17×, ﬁve stars at 47×, and six stars
at 87×. They're arranged in two nearly parallel lines of
three stars each, running southeast-northwest. Starting
at the long line's northern end, the stars gleam yellowwhite, blue-white, and white. The northernmost star in
the short line burns distinctly orange, but the others
are too faint to judge. Three WDS stars weren't noted by
Herschel or me: close companions to the group's southernmost star and its brightest star, as well as a dim star
41″ northwest of the brightest star. The entire collection
would ﬁt within a petite 4.0′ × 2.1′ oval. ✦

F
H

CD
G

Sergio Eguivar took this LRGB image of the multiple-star system
NGC 2017 under rural skies with a 6-inch Newtonian reﬂector.

Sights in the Southern Hare
Object

Type

Magnitude (v)

Size/Sep

Declimation

Messier 79

Globular cluster

7.7

9.6′

05h 24.2m

-24° 31′

NGC 1886

Edge-on galaxy

12.7

3.1′ × 0.4′

05h 21.8m

-23° 49′

05.0m

-26° 44′

01.1m

-23° 40′

ESO 489-1

Cluster remnant?

9.2

11′

06h
06h

NGC 2139

Flocculent galaxy

11.6

2.6′ × 1.9′

γ Leporis

Double star

3.6, 6.3

95″

05h 44.5m

-22° 27′

NGC 2017

Star group

5.9

4.0′

05h 39.3m

-17° 51′

Angular sizes and separations are from recent catalogs. Visually, an object's size is often smaller than the cataloged value and varies according to
the aperture and magniﬁcation of the viewing instrument. Right ascension and declination are for equinox 2000.0.

Februar y 2016 sky & telescope

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Sky and Telescope - February 2016

Table of Contents for the Digital Edition of Sky and Telescope - February 2016