Astronomy: The Week Ahead – Mon 13 Apr – Sat 18 Apr 2015

NASA's Spitzer and Hubble Space Telescopes joined forces to create this striking composite image of one of the most popular sights in the universe. Messier 104 is commonly known as the Sombrero galaxy because in visible light, it resembles the broad-brimmed Mexican hat. However, in Spitzer's striking infrared view, the galaxy looks more like a "bull's eye."

In Hubble's visible light image, only the near rim of dust can be clearly seen in silhouette. Recent observations using Spitzer's infrared array camera uncovered the bright, smooth ring of dust circling the galaxy, seen in red. Spitzer's infrared view of the starlight, piercing through the obscuring dust, is easily seen, along with the bulge of stars and an otherwise hidden disk of stars within the dust ring.

Spitzer's full view shows the disk is warped, which is often the result of a gravitational encounter with another galaxy, and clumpy areas spotted in the far edges of the ring indicate young star-forming regions.

The Sombrero galaxy is located some 28 million light-years away. Viewed from Earth, it is just six degrees south of its equatorial plane. Spitzer detected infrared emission not only from the ring, but from the center of the galaxy too, where there is a huge black hole, believed to be a billion times more massive than our Sun.
 This magnificent galaxy has a diameter that is nearly one-fifth the diameter of the full Moon. Image courtesy of NASA's Spitzer and Hubble Space Telescope.

NASA’s Spitzer and Hubble Space Telescopes joined forces to create this striking composite image of one of the most popular sights in the universe. Messier 104 is commonly known as the Sombrero galaxy because in visible light, it resembles the broad-brimmed Mexican hat. However, in Spitzer’s striking infrared view, the galaxy looks more like a “bull’s eye.”

In Hubble’s visible light image, only the near rim of dust can be clearly seen in silhouette. Recent observations using Spitzer’s infrared array camera uncovered the bright, smooth ring of dust circling the galaxy, seen in red. Spitzer’s infrared view of the starlight, piercing through the obscuring dust, is easily seen, along with the bulge of stars and an otherwise hidden disk of stars within the dust ring.

Spitzer’s full view shows the disk is warped, which is often the result of a gravitational encounter with another galaxy, and clumpy areas spotted in the far edges of the ring indicate young star-forming regions.

The Sombrero galaxy is located some 28 million light-years away. Viewed from Earth, it is just six degrees south of its equatorial plane. Spitzer detected infrared emission not only from the ring, but from the center of the galaxy too, where there is a huge black hole, believed to be a billion times more massive than our Sun.

This magnificent galaxy has a diameter that is nearly one-fifth the diameter of the full Moon.
Image courtesy of NASA’s Spitzer and Hubble Space Telescope.

mon

Monday April 13

In the small constellation Vulpecula is a nice binocular target named the Coathanger, named for its obvious shape. Find the bright star Altair in Aquila as a starting point. The Coathanger is an asterism. It makes a shape, but is not a constellation, nor is it a cluster of stars. These are random stars that line of sight forms into a shape.

It was discovered in ancient Persia, by the astronomer Al Sufi, and described in his Book of Fixed Stars in 964.

tue

Tuesday April 14

M15 is a fine globular cluster in the constellation Pegasus, visible now before sunrise above the eastern horizon. It is a bright fuzzy spot in binocular, and will break up into individual stars in telescopes of over eight inches.

It is condensed, with most of its stars near the core, and sits a bit further than most of the brightest globulars, at 33,000 light years. Jean-Dominique Maraldi discovered it in 1746, and was included it in Charles Messier’s famous catalogue in 1764. At 12 billion years, it is among the oldest objects known.

wed

Wednesday April 15

Gemini’s Beta star, the second brightest, is Castor. The Alpha or brightest star is Pollux. They form the celestial twins of Gemini. In reality, Castor is a bit brighter. It is also a double star, but not a binary. This double, which can be viewed in small telescopes, is a “line of sight” double star, not an actual gravitationally bound pair.

One way of keeping straight which of the twins Castor is, is to recall it begins with letter C, and is on the side of Gemini that you’d look to find Capella, in Auriga. The two C named stars on one side.

thu

Thursday April 16

Two lesser known spring constellations are on the rise, Corvus and Crater. They are west of Virgo above the eastern span of Hydra.

Corvus contains the brighter stars, and resembles a sail. In mythology it is a raven or crow, associated with Apollo.

Crater is The Cup, the cup of Apollo in Greek mythology.

Both constellations date to Ptolemy, and are among the original 48 constellations.

fri

Friday April 17

Mu Draconis is an excellent double star in Draco, near the dragon’s head. Use the Big and Little Dippers to find a pair of brighter stars above them. Make a right angle up from the brighter of the two. Also use the two brightest stars in the dragon’s head as a measure. From the brighter one Mu is about half the distance past the dimmer one and down.

Mu is a binary with a combined magnitude of 4.92, 85 light years distant. They are 2.3″ apart and each shine at an identical magnitude 5.7. You can separate them in a 60mm telescope. This is a showpiece pair!

sat

Saturday April 18

M63 is a bright galaxy in the constellation Canes Venatici, located about 1/3rd the distance between its bright star Cor Caroli and the end star of the Big Dipper’s handle. At magnitude 8.6 with a generous size of 13 arcminutes, it is visible even in small telescopes.

M63 was discovered by Pierre Méchain on June 14, 1779, and added to Charles Messier’s catalog of “non-comets”. It is a classic spiral galaxy, part of the M51 group, and also known as the Sunflower Galaxy. Get to a darker sky tonight, and try this one.

Happy viewing!

Crash

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