Sky and Telescope - May 2017 - 30

Interacting Galaxies

The Tadpole Galaxy
Collider
Galaxy

UGC 10214

debris tail extending east was easily seen as a delicate, low
surface brightness plume, nearly tripling the length of the
galaxy. A couple of miniscule condensations sparkled, including one right at the tip. A 2003 HST study using the newly
installed wide-ﬁeld Advanced Camera for Surveys (ACS)
concluded these clumps are super-massive clusters only 4 to
5 million years old. With time, they may evolve into dwarf
companions in the Tadpole's halo.

N
p THE INTERLOPER The long plume of stars and dust trailing behind
the spiral galaxy UGC 10214, the residue of its collision with a smaller
galaxy, gives it the appearance of a tadpole racing across a pond. Close
examination of UGC 10214's remaining structure reveals the guilty party,
a compact, blue galaxy still entangled in the larger galaxy's spiral arms.

million years ago, separated a major spiral arm from the galaxy
and stretched it into a dramatic plume, rich in dust and gas.
The galaxy's distance of 420 million light-years implies the
Tadpole's tail unfurls across some 280,000 light-years!
In the 48-inch the main section of the galaxy extended
1.2′ × 0.6′ and encompassed an elongated central bar. The

Arp 84 (VV 48), the interacting pair NGC 5394 and NGC
5395 in Canes Venatici, is another stunner through the
48-inch at 610×. The ﬂattened halo of 11.4-magnitude NGC
5395, which forms the Heron's "body" and "wings," spans
2.5′ × 1.0′ and envelops a blazing 30″ core. The most exciting
feature is a well-deﬁned, somewhat splotchy arm that wraps
nearly 360° around the galaxy, forming a partial ring.
The arm emerges at the core's north edge, shoots directly
south on the east side, and twists tightly backwards to the
north along the west edge of the halo. A dark absorption lane
clearly separates the luminous central region from this arm. An
irregular offshoot on the north side includes a brighter patch.
NGC 5394, centered 2′ to the north-northwest, is a
compact 13th-magnitude disc only 30″ in diameter with a
strongly concentrated center and brilliant stellar nucleus. The
Heron's neck, a long, thin tidal arm, was easily visible, hooking southeast and nearly touching the northwest arm of

Colliding Galaxies & Where to Find Them
Arp / VV Number
Arp 142 / VV 316

Object
NGC 2936

Type
Irr

NGC 2937

Mag(v)

Size

Dec.

Nickname

1.6′ × 0.9′

09h

13.1

RA
37.7m

+02° 45′

The Penguin and Egg

13.7

0.8′ × 0.4′

09h 37.8m

+02° 45′

06.1m

+55° 26′

Tadpole Galaxy
The Heron Galaxy

Arp 188 / VV 29

UGC 10214

SBc pec

13.7

3.6′ × 0.8′

16h

Arp 84 / VV 48

NGC 5394

SBb pec

13.0

1.7′ × 1.0′

13h 58.6m

+37° 27′

58.6m

+37° 26′

Arp 242 / VV 224

Arp 55 / VV 155

NGC 5395

SAb pec

11.4

2.9′ × 1.5′

13h

NGC 4676A

S0 pec

13.7

2.3′ × 0.5′

12h 46.2m

+30° 44′

46.2m

+30° 43′′

NGC 4676B

SBa pec

13.6

2.0′ × 0.8′

12h

UGC 4881A

Double

14.5

0.9′ × 0.8′

09h 15.9m

+44° 20′

00h

15.9m

+44° 20′

UGC 4881B
Arp 244 / VV 245

Arp 81 / VV 247

NGC 4038

SBm pec

15.1

-

10.3

5.2′ × 3.1′

12h 01.9m

-18° 52′

01.9m

-18° 53′

NGC 4039

SAm pec

10.6

3.1′ × 1.6′

12h

NGC 6621

SBc pec

13.3

2.1′ × 0.9′

18h 12.9m

+68° 22′

11.9

0.6′ × 0.5′

18h

+68° 21′

NGC 6622

E/S0 pec

13.0m

The Mice

The Grasshopper

The Antennae

Edward's Galaxy

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.

30

M A Y 2 0 1 7 * SK Y & TELESCOPE

N ASA / HOLL A ND FORD (JHU) / ACS SCIENCE TE A M / ESA

The Heron Galaxy
Sky and Telescope - May 2017

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