Composite image by Christmann. Background (Quintuplet Cluster), credit NASA Hubble Telescope. Inset (WR 104: Pinwheel Star), credit U.C. Berkeley Space Sciences Laboratory, W.M. Keck Observatory.

Enjoy our starry night skies

Be a considerate neighbor: Reduce nighttime glare.
Shield your outside lights downward, so no glare goes up to dull the night sky (or into your neighbor’s windows) and enjoy the beautiful, stars above.

April 2008 Night Sky

—CHARLIE CHRISTMANN

DEATH SPIRAL

Like a well-regulated clock, WR 104, known as the “Pinwheel,” beautifully spins about its axis every eight months. The cosmic wonder, discovered eight years ago in the constellation Sagittarius, is formed by two massive, hot stars locked in orbit around each other. Like most super-giants leaning toward old age, these stars are puffing off material. Their circular orbits are marked by the spiral tail.

Looking in the direction of Sagittarius, astronomers have located as many as five of these pinwheel-type binaries. Most of them are close to the center of our galaxy, approximately twenty-five thousand light-years away (147 million-billion miles). Astronomers have determined that stars in the pinwheels are massive and short-lived, nearing the end of their lives. Such massive stars will end their existence in a supernova. Massive binary star systems like these actually explode three times in their lives. There are two explosions when each of the pair separately undergoes a core-collapse supernova. Then, a third explosion occurs as the remnants of the two stars spiral into each other and merge.

WR 104 is a bit closer to Earth, estimated to be only eight thousand light-years away. Unfortunately, one of the pair of stars has been classified as a Wolf-Rayet type. Astronomers believe that these types of stars are “ticking time-bombs,” on their final countdown to exploding.

When a Wolf-Rayet goes supernova, according to Peter Tuthill, an astronomer at the University of Sydney, they may emit an intense beam of gamma rays from their rotational poles like a searchlight beam. If that happens, we really do not want Earth to be in the way. Unfortunately, data published in the March 1st issue of Astrophysical Journal indicates we may be in that searchlight, though more observations are needed to confirm that. Even at eight thousand light years distance, the long-term effects of the gamma rays would be devastating to our atmosphere and ozone layer, allowing the Sun’s UV rays to reach the surface.

But this may not be the end for Earth—there are still many variables, like how close we actually are to the beam’s center, and there is still controversy over whether stars like WR 104 are capable of producing a fully-fledged gamma ray burst in the first place.

BYE-BYE, RINGS

If you have a telescope or good binoculars, take a good look at Saturn and enjoy its rings. The rings are disappearing. They will be gone by early September 2009. But don’t worry—they’ll be back. Over the course of about thirty years, as Saturn orbits the Sun, the angle of the rings, as seen from Earth, oscillates up and down. The best viewing of the rings happened in early 2003 when the tilt reached its maximum of twenty-seven degrees, showing their southern side. Now they are tilting back toward zero degrees so that we will only see them edge-on. And being less than three miles thick, they seem to disappear. In another fifteen years, the rings will be back to full glory. Then we can enjoy a view of the rings’ northern side.

THE PLANETS AND THE MOON

• Look for Mercury the first week in April rising about thirty minutes ahead of the Sun in the east. It will be closer to the Sun as the days pass.

• Venus is also up ahead of the sun, shining brightly in the east, but it rises earlier each day. Enjoy a great show about ten minutes before sunrise on the 4th as Venus clears the horizon with the thin crescent Moon just above and to the right. If you are careful not to look at the Sun (use the edge of a structure to block the Sun for safety), use binoculars to find Venus during the daylight hours using the Moon as a reference.

• Mars is high in the western sky at sunset. • Look for the Moon and Mars about an hour after sunset on the 11th. Bright Capella will be to the right of the Moon, Betelgeuse and Rigel below, and Procyon to the left and a bit below.

• At mid-month, Jupiter is rising at 2:00 a.m. and will be just slightly less bright than Venus. The Moon joins Jupiter in the southern sky about forty-five minutes before sunrise in the southern sky on the 27th.

• Saturn is well up in the southern sky after sunset. Check out the grouping of the Moon, Saturn, and Regulus an hour after sunset on the 15th in the southern sky.

• The Moon is new at 9:55 p.m. on the 5th and full at 4:25 a.m. on the 20th. Lunar perigee (224,366 miles from Earth) occurs on the 7th at 1:30 p.m. Lunar apogee (252,242 miles from Earth) happens at 3:55 a.m. on the 23rd.

If you have a question or comment for Charlie, you may email him at: k5cec@yahoo.com.

Astronomical Society hosts star party in Edgewood

On April 11, The Albuquerque Astronomical Society (TAAS) and the Edgewood Parks Department will host the Edgewood Star Party at Wildlife West Nature Park, just north of I-40 and just west of the Edgewood exit.

Telescopes will be set up in a flat field, shielded from the highway light. The field is next to a pole barn, where last year, spiced apple cider was served. Peer at galaxies in the Virgo and Coma clusters. See Saturn in the constellation Leo. Gaze at the Whirlpool Galaxy’s spirals, which grace the night sky. Observe, through telescopes, resolved stars of the M3 globular cluster.

To get to the park, take I-40 east to the Edgewood exit. Go under the freeway, and turn left immediately past the highway. Follow this road approximately a mile to Wildlife West’s entrance. Observing will commence at sunset. Pets are not allowed in the viewing area. For information, visit www.taas.org or call 254-TAAS. The party is free of charge and is open to the general public.

Gear up for Astronomy Day, Cosmic Carnival 2008

This year’s Astronomy Day will once again be celebrated in New Mexico as a part of Cosmic Carnival 2008. The event is scheduled for Sunday, April 20 from 12:00 noon to 6:00 p.m. Cosmic Carnival will partner with the City of Albuquerque’s Fiesta de Albuquerque in the Old Town Plaza area. The city will close all of the plaza area to vehicular traffic and create a giant pedestrian zone. This year’s astronomy and science exhibitors will be located on Church Street, which is one block north of the plaza behind the church.

Already a number of exhibitors have signed up to participate. They include Explora, the New Mexico Museum of Natural History, the Atomic Museum, the Very Large Array, the Magdalena Ridge Observatory, and Sunspot. Albuquerque Astronomical Society members are encouraged to bring telescopes to the event for public viewing. The event is always exciting and fun and is a good precursor for next year’s International Year of Astronomy.

For more information, visit www.cosmiccarnival.org.