Skip to main content

The Sky This Month - May 2010

Posted in
Written by Gary Boyle, Ottawa on
Post Date: 
Sun, 2010/05/02

Corvus The Crow

Spring is a wonderful time of year for many reasons. There is the annual planting of flowers, reseeding the lawn or even painting the house or apartment. It is also known in the astronomy community as galaxy season. With semi dark skies, these distant islands containing hundred of billions of stars each, stretch all the way from Ursa Major (the Big Dipper) in the north, down through Coma Berenices, ending at Virgo in the south. If hunting galaxies is your passion, you have come to the right place. Hundreds of objects stretch across ninety degrees of sky.

Just off to the right of Virgo in the south and above Hydra, is a small trapezoid of four suns, shining at roughly third magnitude each. Here we find Corvus the Crow or Raven. It too has its fair share of galaxies embedded within its territory. But first, lets first a look at a couple of individual stars.

 

 

The top left star of the trapezoid is called Algorab. Designated as the bird’s right wing, Algorab is only 88 light years away. It is a double star consisting of a third magnitude white B class star and a magnitude 8.5 orange K class star. They separation is 600 astronomical units or seven and a half of our solar systems lined up side by side. As a result, the K star orbits once every 9,000 years or so.

Turning to the raven’s left wing, we come across Gienah Corvi. It is a blue giant star with a surface temperature of 12,400 degrees Celsius or a bit more than twice that of our Sun. It lies 166 light years from us and spins 150 kilometers per second on its axis compared to the Sun’s two kilometers per second. When referring to this star, be sure not to confuse it with Gienah in Cygni.

Located within the trapezoid is the only planetary nebula residing in Corvus. NGC 4361 appears as a fuzzy, tail less comet in small scopes. Its overall magnitude of 10.3 is accented by the 13th magnitude central star that is now entering the white dwarf phase. This, as well as all planetary nebulas are the remains of a once great sun that has used up its fuel.

The first of four interesting objects is NGC 4027. Also catalogued as ARP 22, this peculiar face on barred spiral galaxy is located 68 million light years away or when dinosaurs were probably still roaming the Earth. Its distorted single arm is probably the result of a collision with another galaxy a long time ago.

Speaking about collisions, make sure you look for the Antennae galaxies. They are listed as NGC 4038 and 4039 and are located three and a half degrees west and south of Gienah. This is one of the best examples of colliding galaxies. They might seem to be unique but there are many examples of this cosmic interaction throughout the universe. Another fine example is The Mice.

In the case of the Antennae, as the two galaxies blend together, the stretched and distorted galactic arms formed a likeness to a bug’s antennae. When the fire works are over, astronomers believe the two galaxies will eventually form one large elliptical galaxy. NGC 4038/4039 lies roughly 55 million light years away.

Before you leave the area, there is a classic example of an edge on galaxy. Although it is technically not in Corvus by is a mere five arc minutes from the border line separating Corvus and Virgo, we have M104. Known as the Sombrero Galaxy, this gem is some 30 million light years from us.

The planet Mars is shrinking visually in size. It is about half the size from February. With our two worlds still separating in distance and its angle to the Sun shifting a bit, the Red Planet is taking on a more gibbous phase and dimming as the weeks go by.

Saturn is well placed in the constellation Virgo as the sky darkens. It is still in retrograde till May 31st and continues to move westward with the stars. Next month it then resumes its eastward motion. Because Saturn’s rings are still aimed at Earth, the tilt of the ring system is a thin 1.7 degrees. As the months and years trek on, the rings will eventually open to all its grandeur.

 

Object

Type

Magnitude

Coordinates

M104

Galaxy

8.3

RA:12h 40m  0.0s  Dec:-11d 37'

NGC 4027

Galaxy

11.1

RA:11h 59m 30.0s  Dec:-19d 16'

NGC 4361

Galaxy

10.3

RA:12h 24m 30.0s  Dec:-18d 48'

Antennae Galaxies

Interacting Galaxies

10.4

RA:12h 01m 54.0s  Dec:-18d 52'

 

Only a couple of months ago we said farewell to the planet Jupiter. Well the King of Planets is back and now in the constellation Pisces. It rises about 5:00 a.m. local time at the beginning of the month low in eastern skies.

On May 16th, look for the 10% crescent moon very close to M35. This pair would make a very nice portrait. Then five nights later, Venus swings to the north M35 for another Kodak moment. New moon occurs on the 13th and full phase on the 27th.

Till next month, clear skies everyone.

Gary Boyle