Stunning Conjunction of Mars and Beta Scorpii This Week

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Face south tomorrow morning at the start of dawn and you might have to look twice for Beta Scorpii. Bright Mars stands right next to the star and will pass very close to the star on Wednesday morning, March 16. Diagram: Bob King, source: Stellarium

Planets can sneak up on you. Especially the ones that don’t rise till you’re in bed. Take Mars for instance. It’s been ambling east along the morning zodiac all winter long; today it enters Scorpius, rising around 1:30 a.m. Not two days later, the planet will have a spectacularly close conjunction with Beta Scorpii, the topmost star in the scorpion’s head.

This close up of the head of Scorpius shows Mars' progress over the next three mornings. Positions are shown for 5:30 a.m. CDT. Diagram: Bob King, source: Stellarium
This close up of the head of Scorpius shows Mars’ progress over the next three mornings. Positions are shown for 5:30 a.m. CDT. Diagram: Bob King, source: Stellarium

Also known as Graffias, Beta shines at magnitude +2.6  next to the fiery, zero-magnitude Mars. With their striking color contrast, the two would make a superb ring setting: a tiny diamond nestled next to a plump garnet. They’ll be together for several mornings, their separation changing each day: 15 arc minutes on Tuesday (1/2 the diameter of the Full Moon); 9 arc minutes when closest on Wednesday and back out to 23 minutes on Thursday.

In a telescope, diminutive Mars pairs up with gorgeous Graffias. Diagram: Bob King , source: Stellarium
In a telescope, diminutive Mars pairs up with gorgeous Graffias. North is up and left. Beta-1, the brighter of the two, has an additional 1oth magnitude companion half an arc-second away, while Beta-2 is also double with a faint companion 1/10th of arc second distant. That’s not all. Beta-1 is an exceedingly close binary — making Graffias at least a five-star system!  Diagram: Bob King , source: Stellarium

It’s a gas to see two celestial objects approach so closely, but this conjunction offers a rare treat. Did you know that Beta is one of the finest double stars in the sky? It has a fifth magnitude companion 14 arc seconds northeast of the primary. Any telescope will split this jewel and show Mars in the same field of view at both high and low magnifications. That’s just so cool — I sure hope you’ll get to see them.

Mars, in gibbous phase, is still small but starting to show its larger surface features in modest-sized telescopes. This photo, taken on March 13th, shows the  prominent Mare  Acidalium in the planet's northern hemisphere (top) and a hint of the north polar cap. Sinus Aurorae and Mare Erythraeum dominate the south. Credit: Anthony Wesley
Mars, in gibbous phase, is still small but its larger surface features are now visible in modest-sized telescopes. This photo, taken on March 13th, shows Mare Acidalium in the planet’s northern hemisphere (top) and a hint of the north polar cap. Sinus Aurorae and Mare Erythraeum dominate the south. Click for a Mars map. Credit: Anthony Wesley

Mars now measures 10 arc seconds in diameter, small for sure, but big enough to see the larger dark markings and a hint of the north polar cap. The planet is heading for opposition on May 22nd, when it will shine at magnitude -2.0 (brighter than Sirius) with a disk 18.4 arc seconds across, its biggest and closest since 2005.

Let this week’s lovely conjunction serve as a warm-up to the forthcoming season of Mars.

 

New Binocular Nova Discovered in Sagittarius

Looks like the Sagittarius Teapot’s got a new whistle. On March 15, John Seach of Chatsworth Island, NSW, Australia discovered a probable nova in the heart of the constellation using a DSLR camera and fast 50mm lens. Checks revealed no bright asteroid or variable star at the location. At the time, the new object glowed at the naked eye limit of magnitude +6, but a more recent observation by Japanese amateur Koichi Itagaki puts the star at magnitude +5.3, indicating it’s still on the rise. 

A 5th magnitude nova’s not too difficult to spot with the naked eye from a dark sky, and binoculars will show it with ease. Make a morning of it by setting up your telescope for a look at Saturn and the nearby double star Graffias (Beta Scorpii), one of the prettiest, low-power doubles in the summer sky.

Close-in map of Sagittarius showing the nova's location (R.A. 18h36m57s Decl. -28°55'42") and neighboring stars with their magnitudes. For clarity, the decimal points are omitted from the magnitudes, which are from the Tycho catalog. Source: Stellarium
Close-in map of Sagittarius showing the nova’s location (R.A. 18h36m57s Decl. -28°55’42”) and neighboring stars with their magnitudes. For clarity, the decimal points are omitted from the magnitudes, which are from the Tycho catalog. Source: Stellarium

Nova means “new”, but novae aren’t fresh stars coming to life but an explosion occurring on the surface of an otherwise faint star no one’s taken notice of – until the blast causes it to brighten 50,000 to 100,000 times. A nova occurs in a close binary star system, where a small but extremely dense and massive (for its size) white dwarf siphons hydrogen gas from its closely orbiting companion. After swirling about in a disk around the dwarf, it’s funneled down to the star’s 150,000 F° surface where gravity compacts and heats the gas until detonates in a titanic thermonuclear explosion. Suddenly, a faint star that wasn’t on anyone’s radar vaults a dozen magnitudes to become a standout “new star”.

Novae occur in close binary systems where one star is a tiny but extremely compact white dwarf star. The dwarf pulls material into a disk around itself, some of which is funneled to the surface and ignites in a nova explosion. Credit: NASA
Novae occur in close binary systems where one star is a tiny but extremely compact white dwarf star. The dwarf pulls material into a disk around itself, some of which is funneled to the surface and ignites in a nova explosion. Credit: NASA

Regular nova observers may wonder why so many novae are discovered in the Sagittarius-Scorpius Milky Way region. There are so many more stars in the dense star clouds of the Milky Way, compared to say the Big Dipper or Canis Minor, that the odds go up of seeing a relatively rare event like a stellar explosion is likely to happen there than where the stars are scattered thinly. Given this galactic facts of life, that means most of will have to set our alarms to spot this nova. Sagittarius doesn’t rise high enough for a good view until the start of morning twilight. For the central U.S., that’s around 5:45-6 a.m.

A now-you-see-it-now-you-don't animation showing the nova field before and after discovery. Credit: Ernesto Guido and Nick Howes
A now-you-see-it-now-you-don’t animation showing the nova field before and after discovery. Credit: Ernesto Guido and Nick Howes

Find a location with a clear view to the southeast and get oriented at the start of morning twilight or about 100 minutes before sunrise. Using the maps, locate Sagittarius below and to the east (left) of Scorpius. Once you’ve arrived, point your binoculars into the Teapot and star-hop to the nova’s location. I’ve included visual magnitudes of neighboring stars to help you estimate the nova’s brightness and track its changes in the coming days and weeks.

Whether it continues to brighten or soon begins to fade is anyone’s guess at this point. That only makes going out and seeing it yourself that much more enticing.

New photo of Nova Sagittarii. Note the pink color from hydrogen alpha emission. Credit: Erneso Guido and Nick Howes
New photo of Nova Sagittarii. Note the “warm” color from hydrogen alpha emission. Credit: Erneso Guido and Nick Howes

UPDATE: A spectrum of the object was obtained with the Liverpool Telescope March 16 confirming that the “new star” is indeed a nova. Gas has been clocked moving away from the system at more than 6.2 million mph (10 million kph)!