The Star-Clad Maiden: Visit Virgo to find these exemplary galaxies of spring.
--William Henry Smyth, The Bedford Catalogue, 1844
This charming quatrain tells us how to find the star Vindemiatrix in Virgo using the Alpha stars of Hydra, Bootes, and Canes Venatici as guides. The tie between Virgo and the Roman god Bacchus (Greek Dionysus) has many versions, but a woeful tale is told by Julius D. W. Staal in his wonder ful book The New Patterns in the Sky. Bacchus taught Icarius, a mortal man, the art of winemaking. Icarius shared his newly created libation with friends and local shepherds, who mistook their intoxication for attempted poisoning and slew poor Icarius. His body, tossed aside in a ditch, was found by his faithful dogs and his daughter Erigone. In their grief, they followed him into death. Icarius was then placed in our sky as Bootes, his dogs as Canes Venatici, and Erigone as Virgo.
The area of the sky we'll be visiting lies west of Vindemiatrix and within the Virgo Cluster, which hosts about 1,500 galaxies. The cluster's main body is centered on the hefty galaxy Messier 87, sitting 54 million light-years away from us. Including dark matter, M87 weighs in at roughly 10 trillion solar masses or around 10 Milky Way galaxies.
Through my 130-mm refractor at 23x, M87 is an obvious glow just south of a deep-yellow, 8.6-magnitude star. It appears slightly oval at 63x and brightens considerably toward the center. Examined at 117x, M87's brightness contours become rounder as you approach the center, and they enfold a small, brilliant core. The halo has indefinite boundaries, but I'd put the size at about 4V2'. Nearby NGC 4478 is also visible, looking fainter and more obviously oval than M87. Its plump profile tilts northwest and is roughly V long. While gazing at NGC 4478, I noticed NGC 4476 with averted vision.
It's a bit smaller but more elongated than NGC 4478, leaning northnortheast, and too faint to disclose any details.
NGC 4478 and NGC 4476 delineate the top of an 8.2'--tall trapezoid that they form with two llth-magnitude stars to their south-southwest.
My 10-inch reflector at 187x shows M87's 5'-long face cocked north-northwest. The interior is bright to a diameter of approximately 2Vi, and it grows much brighter toward the center. NGC 4478 is easy to spot, covering about 1W. Its fairly bright core intensifies inward to a tiny nucleus. NGC 4476 shows well now, brightening slightly toward an elusive nucleus.
M87 is famous for its narrow plasma jet, which is powered by the accretion disk around the galaxy's central, supermassive black hole. It's not surprising that amateur astronomers would love to see this beast, but it's quite astonishing that many have succeeded. This isn't an undertaking for the faint of heart. Those who have succeeded are accomplished observers working under excellent skies and using magnifications of about 400x. Most utilized 20-inch and larger telescopes, but some triumphed with scopes as small as 12V2 inches in aperture. From the heart of the galaxy, the jet strikes out west-northwest for about 21", but the part that is most likely to be visible is the stretch from 12" to 18". If you decide to attempt this feat, be careful not to mistake the extremely faint galaxy pair (UGC 7652) 2' southwest of M87 for the jet.
Placing M87 in the western side of the 130-mm scope's 23x field of view brings Messier 89 into view, looking smaller than M87 and round with a bright center. At 63x M89 displays a moderately faint halo, a brighter interior, and a small, intense core--all round. Boosting the magnification to 117x, the scope teases out a starlike nucleus. The galaxy's halo fades into the background sky at a diameter of about 2'. My 10-inch scope at 166x reveals a 13th-magnitude star watching over the halo's east-northeastern edge.
On deep images, M89 sports what appears to be a jet that extends a whopping 10' from the galaxy's center. However, this "jet" is composed of stars and may be the product of an encounter with a smaller galaxy.
Only 20' south of M89, we find the galaxy pair NGC 4550 and NGC 4551. In a 1992 Astrophysical Journal paper, Vera Rubin and colleagues published an amazing find. Rubin later commented, "I discovered from observations of NGC 4550 that in the single disk of this galaxy, half the stars orbit clockwise, and half the stars orbit counterclockwise, both systems intermingled. This observation required that many astronomers modify the manner in which they measured velocities, for computer programs were not then equipped to handle such complexity. A nice discovery to make at age 63!" Few galaxies are known to have such a large dichotomy, a feature that might be due to the merger of two galaxies with misaligned spins.
With a wide-angle eyepiece that gives 117x in the 130-mm scope, NGC 4550 and NGC 4551 share the field of view with M89. The very faint, li^'-long, north-south spindle of NGC 4550 is enclosed in a trapezoidal box of four stars, magnitudes 12 and 13. The box is 51/2' tall, with the galaxy just beneath (west of) its lid. Dimmer and vaguely oval, NGC 4551 rests atop the lid and covers a petite Both galaxies are easily seen in the 10-inch scope at 115x. NGC 4550 presents a large, brighter, elongated interior, while NGC 4551 bears a broadly but only slightly brighter interior. At 187x NGC 4550 stretches across 2'. NGC 4551 is a fat oval tipped east-northeast, bridging T and holding an elusive stellar nucleus.
Messier 58 shares the field of view with M89 through the 130-mm refractor at 23x. Compared to its field mate, M58 is larger with lower surface brightness, but it grows more luminous toward the center. An 8th-magnitude star sits 7.6' due west. At 63x its oval form tips east-northeast, and at 117x the oval enfolds a tiny, vivid nucleus and is swathed in a rounder, dim, 3 1/2' halo. My 10-inch 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 117x 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 164x 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 in the 10-inch scope at 115x, each galaxy holding a somewhat brighter, elongated interior. NGC 4568 is about 3' x 1', tipped north-northeast, and harbors a tiny nucleus. NGC 4567's oval spans 2W, 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. The name was coined by Leland S. Copeland, the first Deep-Sky Wonders columnist, and introduced in the May 1946 issue of Sky <Sc Telescope.
Because they look relatively undisturbed in the eyepiece and 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 firstname.lastname@example.org.
Caption: This deep image of the Virgo cluster represents more than 36 hours of exposure time. One easy route to the galaxy cluster hops from Epsilon (e) Virginis (Vindemiatrix) to Rho and 27 Virginis. From those stars, it takes just a nudge to bring the galaxies into the field of view.
Caption: Under very high power, the irregular structure of the barred spiral M58 may be revealed. The typical view through an 8-inch reflector is shown here. The galaxy is tipped slightly toward the east-northeast and appears brighter at its core.
Caption: With the right equipment, you may be able to detect the high-energy jet of particles emanating from M87's supermassive black hole. This sketch represents the plasma stream as viewed with a 20-inch Newtonian reflector and deep-sky video camera.
Caption: Above: 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 17-inch astrograph (total exposure time = 18 hours). Inset: Dale Holt's video setup also revealed the distended halos of interacting galaxies NGC 4567 and NGC 4568.
Galaxies in Virgo Object Type Mag(v) Surface Size/Sep Brightness M87 Giant elliptical 8.6 13.0 8.3' x 6.6' NGC 4478 Elliptical 11.5 12.6 1.9'x 1.6' NGC 4476 Lenticular 12.2 12.8 1.7'x 1.1' M89 Elliptical 9.8 12.5 5.1'x 4.7' NGC 4550 Barred lenticular 11.7 12.7 2.9'x 0.8' NGC 4551 Elliptical 12.0 13.0 1.8'x 1.4' M58 Barred spiral 9.7 13.1 5.9' x 4.7' NGC 4564 Elliptical 11.1 12.9 3.5' x 1.5' NGC 4567 Spiral 11.3 13.1 3.0'x 1.4' NGC 4568 Spiral 10.8 13.1 4.3'x 1.0' Object RA Dec. M87 12h 30.8m +12[degrees] 23' NGC 4478 12h 30.3m +12[degrees] 20' NGC 4476 12h 30.0m +12[degrees] 21' M89 12h 35.7m +12[degrees] 33' NGC 4550 12h 35.5m +12[degrees] 13' NGC 4551 12h 35.6m +12[degrees] 16' M58 12h 37.7m +11[degrees] 49' NGC 4564 12h 36.5m +11[degrees] 26' NGC 4567 12h 36.5m +11[degrees] 15' NGC 4568 12h 36.6m +11[degrees] 14' 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:||Deep-Sky Wonders|
|Publication:||Sky & Telescope|
|Date:||May 1, 2018|
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