The last messier: many fascinating galaxies swarm around giant M49.
To ferret out Messier 49, slip 1.9[degrees] southwest from Rho ([rho]) Virginis to a 6.6-magnitude star, the brightest in the area. Extend your sweep for three-quarters that distance farther to arrive at the middle of a nearly straight, 48'-long line of three unevenly spaced stars. The westernmost star is brightest and orange in hue. M49 is 33' northwest of that star, and it's visible through 50-mm binoculars in moderately dark skies.
In 1550 binoculars, M49 appears relatively large, as galaxies go, and sports a small, bright center. It shows an oval profile through my 105-mm refractor at 127, and a tiny, bright nucleus punctuates the galaxy's small, well-defined core. A faint star is superimposed on M49's halo, just east of the core. Viewed in my 10-inch reflector at 118x, M49 covers about 5' x 4'.
The dwarf galaxy UGC 7636 dwells a mere 50" west-northwest of a 12th-magnitude star that guards M49's southeastern edge. According to a paper in Astronomy & Astrophysics (Arrigoni Battaia et al., 2012), the dwarf has suffered much wear and tear from at least two close encounters with M49. As UGC 7636 plowed through M49's hot, dense halo, the resulting pressure stripped the little galaxy of its own supply of gas, quashing star birth within the dwarf. M49's tidal pull abetted this process. It also gave UGC 7636 a tail of stars reaching out toward M49, as well as a counter-tail stretching southwest. The orphaned cloud of turbulent gas eventually developed its own star-forming regions.
UGC 7636 has been seen under very dark skies in scopes as small as 16 inches in aperture. Several other small galaxies flock around M49, as shown in the image on the facing page, but our sky tour will focus instead on some of the brightest galaxies in the region.
To find them, we'll return to the line of stars that helped us locate M49. NGC 4526 lies between its eastern-most and middle star, while NGC 4535 hovers 28' north of the former. These galaxies share the field of view through my 105-mm scope at 47x. NGC 4535 is a softly glowing, 6' x 4', north-south oval that brightens only slightly toward the center. NGC 4526 looks smaller but brighter than its neighbor. Its spindle shape is tipped east-southeast and bears a brighter, somewhat elongated core. At 87xa starlike nucleus appears.
Through my 10-inch scope at 149x, NGC 4535 harbors a small brighter core with short extensions northeast and southwest. This seems to give the galaxy a bar about 1 1/2' long, slanted northeast. In reality this feature is partly made up of the inner regions of two opposed spiral arms. Faint stars dot the galaxy 57" north and 2.2' south of its center. An extremely faint star is intermittently visible just west of the bar's southern extension. It makes a nearly isosceles triangle with the southern star and a brighter star near the galaxy's southwestern edge.
The triple star Struve 1658 ([SIGMA]1658) sits 22' southeast of NGC 4526. In my 105-mm refractor at 17x, the bright, yellow primary star has an orange companion spaciously removed to the west. Relative motion indicates that these stars don't form a true pair. Boosting the power to 87x
unveils a dimmer companion close to and north-northeast of the primary. Its color is difficult to discern, but it seems to be a deeper shade of yellow than the primary. This pair is about 230 light-years away.
NGC 4570 resides 29' east-southeast of Struve 1658. They share the field with NGC 4526 through my 105-mm refractor when I use a wide-angle eyepiece at 47x. NGC 4570 is a very small but easily visible streak tilted north-northwest. At 87x the galaxy displays a relatively large, elongated core and a bright, starlike nucleus. With my 10-inch reflector at 171, I estimate an apparent length of 2 1/2' and a central width of 1/2'.
Returning once again to our handy line of three stars, let's draw an imaginary line from the easternmost to the westernmost star, and then extend the line for twice that distance. This takes us to NGC 4365, which shares the field of view with M49 through my 105-mm refractor at 17x. This small, oval galaxy is adorned with a much brighter center, and it sits at the southwestern corner of a nearly square, roughly 16' box that it makes with three 10th-magnitude stars to its north, northeast, and east. At 87x NGC 4365 is about 4 1/2' 2 3/4', elongated northeast-southwest, and it holds a large, bright, oval core enfolding
a small, brighter nucleus. The galaxy is flanked by a faint star near its northwestern side and a brighter but more distant star off the opposite side.
A yellow, 6th-magnitude star rests 48' northwest of M49. It makes an isosceles triangle with 8th-magnitude stars 1.3[degrees] north-northeast and north-northwest. NGC 4442 lies halfway between these two stars and a bit north of an imaginary line connecting them. My 105-mm scope at 28x shows an elongated galaxy with a much brighter core. At 87x I estimate dimensions of 3.4' x 1', with the galaxy tipped a smidgen north of east. The core appears slightly oval at 122x. Through my 10-inch scope at 187x, the halo is shaped much like a double-convex lens. Faint stars pin its rim south-southwest of the galaxy's nucleus and on the north side of its eastern end.
Two adorable galaxies inhabit the sky near Rho Virginis: NGC 4596 and NGC 4608. Through my 105-mm refractor at 17x, the galaxies are just tiny spots of mist. NGC 4608 is 11' west-southwest of Rho, and NGC 4596 is 19' west of its companion in a north-south zigzag of eight stars, magnitude 9 and fainter. At 87x, the galaxies look like phantom Saturns -- each a ball with faint extensions. NGC 4596's "rings" tilt east-northeast, while those of NGC 4608 are harder to see and lean north-northeast. NGC 4608 is accompanied by a faint star 1.6' west-northwest. NGC 4596's "Saturn" is embedded in a dim halo tipped northwest and has a faint star off its "south pole."
My 10-inch reflector at 187 shows that NGC 4608 has a ghostly, oval halo perpendicular to the plane of "Saturn's rings." When viewed with bright Rho outside the field of view, the halo nearly reaches the galaxy's companion star, and the ringed-planet shape spans about 1 1/2'. NGC 4596 is a bigger and brighter but blurrier-looking Saturn, with a 3 1/2'-long halo.
All the galaxies above are members of the Virgo Cluster, centered 55 million light-years from us.
For a bit of variety, let's plunge southward to Gamma ([gamma]) Virginis, also known as Porrima. From a minimum separation of 0.4" in 2005, its twin components have widened the space between them to 2.2", placing them within reach of a small telescope. These pale yellow-white suns are aligned north-south and are nicely split through my 105-mm scope at 122.
A charming asterism known as the Virgo Diamond sits 2.2[degrees] west-northwest of Porrima. Noah Brosch introduced it in the December 1991 Monthly Notices of the Royal Astronomical Society because he thought it could be an "evaporating small cluster in the Galactic halo."
Through my 130-mm refractor at 23, the Virgo Diamond is a teensy fuzzspot. I can just see four stars marking the corners of a square at 63, and they show quite nicely at 117. At 164 the western star blossoms into a close pair, better appreciated at 234, with the dimmer star east-southeast of the primary. Although most, and possibly all, of its components are now thought to be physically unrelated, this Diamond is a pretty little gem with which to end our tour.
Sue French welcomes your comments at firstname.lastname@example.org.
Galaxies and Stars in South-Central Virgo Object Magnitude Size/Sep. RA Dec. Messier Galaxy 8.4 9.4' x 12h +8[degrees] 00' 49 8.3' 29.8m NGC Galaxy 9.7 7.2' x 12h +7[degrees] 42' 4526 2.4' 34.1m NGC Galaxy 10.0 7.1 x 5.0 12h +8[degrees] 12' 4535 34.3m Struve Multiple 8.1, 9.1, 128", 12h +7[degrees] 27 1658 star 10.5 2.7" 35.1m NGC Galaxy 10.9 3.8' x 12h +7[degrees] 15 4570 1.1' 36.9m NGC Galaxy 9.6 6.9 x 5.0 12h +7[degrees] 19 4365 24.5m NGC Galaxy 10.4 4.6 x 1.8 12h +9[degrees] 48 4442 28.1m NGC Galaxy 10.4 4.0 x 3.0 12h +10[degrees] 11 4596 39.9m NGC Galaxy 11.0 3.2 x 2.7 12h +10[degrees] 4608 41.2m 09' Porrima Double 3.5, 3.5 2.2" 12h -1[degrees] 27' star 41.7m Virgo Asterism 10.4 0.8 12h -0[degrees] 39' Diamond 33.3m 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.
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|Title Annotation:||Wonders, Deep-Sky; Messier 49|
|Publication:||Sky & Telescope|
|Date:||Apr 1, 2014|
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