Australian Sky & Telescope - May 2018

http://www.skyandtelescope.com.au 53

vaguelyoval,NGC4551restsatopthe

lidandcoversapetite¾′. Both galaxies

areeasilyseenthroughthe25-cmscope

at 115×.NGC4550presentsalarge,

brighter,elongatedinterior,whileNGC

4551bearsabroadlybutonlyslightly

brighterinterior.At187×NGC 4550

stretchesacross2′.NGC4551isafat

oval tipped east-northeast, bridging 1′

and holding an elusive stellar nucleus.

Messier 58sharesthefieldof

view with M89 through the 130-mm

refractor at 23×.Comparedtoitsfield

mate,M58islargerwithlowersurface

brightness, but it grows more luminous

toward the centre. An 8th-magnitude

star sits 7.6′due west. At 63×its oval

form tips east-northeast, and at 117×

theovalenfoldsatiny,vividnucleus

andisswathedinarounder,dim,3½′

halo. My 25-cm reflector highlights a

bar-like core. M58’s blazing nucleus is

powered by a supermassive black

hole (weighing in at 50 to 70

million solar masses) fed

by an accretion disk of

infalling matter.

Three additional

galaxies are visible in

the refractor’s low-

power field. Although

they are fairly faint,

NGC 4564 , NGC 4567

and NGC 4568 were

spotted without specifically

looking for them. The last two blend

together as one glow that’s brighter

and chubbier than NGC 4564. At

117 × NGC 4564 displays a brighter,

elongated interior and a small,

radiant core. The faint halo is about

2 ′ long and less than half as wide.

Even at 164× the dual nature of NGC

4567/4568 isn’t clear, but the combo’s

subtly wider north end and two

fugitive, marginally brighter patches

hint at the possibility.

The NGC 4567/4568 galaxies are

well distinguished through the 25-cm

scope at 115×, each galaxy holding a

somewhat brighter, elongated interior.

NGC 4568 is about 3′ × 1 ′, tipped north-

northeast, and harbours a tiny nucleus.

NGC 4567’s oval spans 2¼′, tilts a bit

north of east, and embraces a small,

brighter core. The halos of the galaxies

merge at the eastern end of NGC 4567,

which earns this pair its nickname, the

Siamese Twins.

Because they look relatively

undisturbed through the eyepiece and

in deep sky images, the Siamese Twins

were once thought to be a coincidental

superposition of two unrelated

galaxies. However, recent studies of

their molecular gasses have found

telltale signs indicating the galaxies are

in the early stages of gravitational and

tidal interaction.

„ Contributing Editor SUE FRENCH

welcomes your comments and

observing stories. She can be reached

at [email protected].

SAbove: Because NGC 4567 and NGC 4568 are in the early stages of their merger, the

structure of their spirals is still obvious. This LRGB image shows what can be captured of the

interaction with a 43-cm astrograph (total exposure time = 18 hours). Inset: Dale Holt’s video

setup also revealed the distended halos of the two galaxies.

4476

4551

ρ

4429

4435

4438

4461

4473

4477

4478

M87

4503

4550

M89

4564

4567

4568

M90

M58

M59

4638

4639

4647

M60

4654

4660

VIRGO

12 h 35 m

+13°

12 h 45 m 12 h 40 m 12 h 30 m

+12°

+11°

Star magnitudes

5

6

7

8

9

10

NGC 4567

NGC 4568

N

PHOTO: BILL SNYDER; SKETCH: DALE HOLT