StarDate

It’s hard to look at Hoag’s Object and not think of food. The galaxy’s core looks like an egg yolk, while a ring of stars around it resembles a glazed doughnut. The problem for astronomers is that they’re not sure of the recipe that cooked it up.

Hoag’s Object is about 600 million light-years away. It stands high in the southwest at nightfall, just below the semicircle of stars known as Corona Borealis, the northern crown.

The galaxy’s ring appears to be giving birth to many new stars. But unlike other ring galaxies, there’s not much material connecting the ring to the core.

Hoag’s Object might have started as a spiral galaxy, but was shot through by a smaller galactic “bullet.” The impact would have created ripples that reshaped the spiral. But there’s no evidence of a second galaxy anywhere close.

Another possibility is that a second galaxy sideswiped the bigger spiral. The second galaxy would have been pulled apart and its stars and gas incorporated into Hoag’s Object. But there are problems with this idea, too.

A third possibility is that the galaxy originally had a long bar of stars across its middle. The motions of the bar would have whipped up the galaxy like egg whites in a blender — yet another reminder of food.

So far, astronomers haven’t seen any other galaxies that are just like Hoag’s Object. That leaves them with little help as they try to decipher the recipe for this tasty-looking galaxy.
 

Script by Damond Benningfield

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The swan climbs high across the southern sky on summer nights. It’s marked by its bright tail, the star Deneb. It’s the lower left point of the wide-spread Summer Triangle. The swan’s body angles to the upper right of Deneb, as though the swan were taking flight from a pond. Its long, graceful wings flank its body.

The brightest star of the top wing is Delta Cygni. It’s a system of at least three stars. Two of them are a good bit bigger, brighter, and heavier than the Sun, while the third is less massive than the Sun.

The heavier stars orbit each other at an average distance of almost 15 billion miles — roughly 150 times the distance from Earth to the Sun. But the little guy is much farther out.

It’s possible that when the system was born, the third star was closer in. But as the stars danced their complex orbital ballet, they swapped some of their energy. The lightweight star was pushed outward, while the heavier stars spiraled closer together.

Those stars were pushed into a stretched-out orbit that looks a bit like an oval racetrack. It takes the two stars almost 800 years to make one lap around the track. But the lonely third member of the trio needs more time. It takes many thousands of years to orbit its brighter companions.

Look for Delta Cygni above Deneb as darkness falls. It’s about a third of the way up from Deneb to brilliant Vega, the brightest member of the Summer Triangle.
 

Script by Damond Benningfield

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The surface of a star vibrates like a concert hall where a thousand orchestras are tuning up at once. By separating the different notes, astronomers can learn a great deal about the star. In the case of Aldebaran, the eye of the bull, it revealed that astronomers had been wrong about the star’s mass, which meant they’d been wrong about other things as well.

The vibrations are untangled through a technique known as asteroseismology. Giant cells of hot gas rise and fall through a star’s outer layers. Near the surface, that generates pressure waves. The waves ripple through the star, causing its surface to jiggle up and down a bit. Astronomers can measure those jiggles.

Different waves move through the star in different ways. Piecing together the waves reveals a lot about the star, and what’s happening deep inside it.

A few years ago, astronomers pieced together almost three decades of observations of Aldebaran. Among other things, they showed that estimates of Aldebaran’s weight were all wrong. Instead of 70 percent more massive than the Sun, it was only 16 percent heavier. And since a star’s mass determines how quickly it ages, that meant that Aldebaran was about six and a half billion years old — a billion and half years older than earlier estimates.

Look for Aldebaran near the Moon the next couple of mornings. The bright star is below the Moon at first light tomorrow, and to the right of the Moon on Sunday.
 

Script by Damond Benningfield

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SS 433 is the only member of its kind in the entire galaxy: a micro-quasar. It consists of a supergiant star, a black hole, a disk of super-heated gas around the black hole, and corkscrews of particles firing into space at a quarter the speed of light.

Full-size quasars are found in the hearts of galaxies. They’re powered by black holes that can be billions of times the mass of the Sun.

SS 433 isn’t nearly that big or massive. The black hole is perhaps eight times the mass of the Sun, with its companion a little bigger. Hence, a micro-quasar.

The two objects are so close together that the black hole pulls gas from the star. The gas forms a swirling disk before most of it falls into the black hole. So much gas is pouring in that it’s super-heated. It emits huge amounts of X-rays, so it’s especially bright.

The black hole shoots some of the infalling gas back out into space. The gas forms two jets — one from each pole. The black hole is wobbling, so the gas spirals out like water from a spinning lawn sprinkler. Seen in profile, the jets form corkscrews that are many light-years long — part of the only micro-quasar in the Milky Way Galaxy.

SS 433 is in the southeast at nightfall. It’s to the upper right of Altair, the leading light of Aquila, the eagle. Despite SS 433’s brilliance, you need a fairly big telescope to see it.
 

Script by Damond Benningfield

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This is a big week on the planet Mars. For one thing, today is the anniversary of the first successful landing on the Red Planet. Viking 1 touched down in 1976 and operated for more than six years. It revealed a lot about the planet’s rocks and soil, its weather, and its history. One of its instruments even found evidence of microscopic life, although most scientists refuted the finding.

And tomorrow marks the solstice on Mars — the start of winter in the northern hemisphere and summer in the southern hemisphere.

Mars has seasons for the same reason that Earth does — it’s tilted on its axis. But Mars’s distance from the Sun varies much more dramatically than Earth’s does, so there’s a bigger difference in seasonal climate. Right now, Mars is close to the Sun. The extra solar energy means that winter is milder in the north than the south, while southern summer is hotter than in the north. Of course, that’s all relative — temperatures seldom climb above freezing.

The new season will last about 154 days — only northern autumn is shorter. And those are Mars days, which are about 40 minutes longer than Earth days — extra time to enjoy a mild winter climate.

Mars is easy to pick out tonight because it snuggles close to the Moon. They climb into good view by about 2 a.m., and are high in the sky at first light. Mars looks like a bright orange star to the lower left of the Moon.
 

Script by Damond Benningfield

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The heart of the galaxy is filled with many wonders: a supermassive black hole, thousands of pulsars, looping magnetic fields, and odd sources of radio waves.

Perhaps the oddest of the radio sources was reported last year. It’s no more than about 30,000 light-years away, toward the center of the galaxy. That suggests that it’s in the Milky Way’s busy heart.

Astronomers watched the object — which doesn’t have a proper name — for two years.

At first, it would switch on and stay on for weeks, although its brightness varied dramatically. Later, though, it appeared and disappeared in as little as a day. And its light was polarized — all the radio waves lined up like a marching band. The astronomers looked for the object at many other wavelengths, with telescopes on the ground and in space. But they saw nothing.

The astronomers say it’s not a single star, a binary star, or a pulsar — a dead star that flickers with a steady beat. They’ve also ruled out anything beyond the Milky Way.

It’s similar to a class of objects known as galactic center radio transients, which also are poorly understood. But there are many differences, too. So it could be something new — a new addition to the list of wonders at the heart of the galaxy.

Although you can’t see it, the object is quite low in the south-southeast at nightfall. It’s to the right of the Sagittarius “teapot” and just above the “stinger” at the tail of the scorpion.
 

Script by Damond Benningfield

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You never know what astronomers will turn up next. In the case of a stellar nursery in the heart of the galaxy, they found ethyl formate — the molecule that gives raspberries their flavor. Since it smells a bit like rum, it’s been called the “raspberry rum” molecule.

B2 is a cloud of gas, dust, and young stars, about 400 light-years from the center of the Milky Way. It’s one of the biggest and busiest in the entire galaxy: It spans about 150 light-years, is eight million times the mass of the Sun, and has given birth to more than 30,000 stars. Most of the stars are small and faint, but a few are monsters — dozens of times the mass of the Sun.

The entire cloud is filled with complex molecules. B2 contains just about every molecule seen anywhere outside our solar system; about half of them were discovered there.

The list includes ethyl alcohol, formaldehyde, and a cyanide compound. Some of the molecules are among the chemical building blocks of amino acids, the building blocks of life. That includes the raspberry rum molecule — a sweet hint that the ingredients for life can be found in the stars.

B2 is about 27,000 light-years away, in Sagittarius. The constellation is low in the southeast at nightfall, and looks like a teapot. B2 is in the “steam” above the spout — a fragrant stellar nursery immersed in the glow of the Milky Way.

More about the center of the galaxy tomorrow.
 

Script by Damond Benningfield

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The more we know about Jupiter, the less we know — at least about its birth. There are competing ideas about where it was born, which require different models of how it was born.

Jupiter is about two and a half times as massive as all the other planets combined. To reach that mass, the planet had to take shape far from the Sun, where conditions were nice and cold.

But just how far remains unclear. Some models say it was born at about two-thirds of its current distance from the Sun. It then moved closer to the Sun before sliding out to its present spot.

In the last few years, though, other models have emerged. In these, Jupiter was born at many times its current distance from the Sun — far beyond Pluto. That range would account for high amounts of nitrogen and other compounds in Jupiter’s atmosphere. They need extremely cold temperatures to form solid grains, which would be easier for the newly forming planet to incorporate. Those frigid conditions would have existed only far out from the Sun.

But the ideas of how it took shape there are still taking shape themselves. So there’s no agreement at all on how and where the giant planet was born.

You can ponder those questions as you look at Jupiter after midnight the next couple of nights. The planet looks like a brilliant star. It’s to the upper left of the Moon at dawn tomorrow, and closer to the upper right of the Moon on Tuesday.

Tomorrow: young stars and raspberry rum.
 

Script by Damond Benningfield

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To find life on worlds beyond the solar system, look for the color. Some microscopic organisms are brightly colored — pink, yellow, orange, green, and other vivid hues. If these organisms congregate in large areas on other worlds, they could show up in images from future telescopes.

Astronomers have discovered more than 5,000 exoplanets — worlds in other star systems. With our current telescopes, we can’t see any of them as more than bright dots of light — no details at all.

Most current efforts to find life are looking for the chemical markers of life in planetary atmospheres — a combination of oxygen and methane, for example. But astronomers are designing big new telescopes that could give us crude pictures of some of these planets.

In recent years, a couple of studies have looked at the colors of microorganisms here on Earth. One study looked at organisms on land. The other took samples from in and around Hudson Bay in Canada.

Researchers analyzed the colors and what might make them easier to see from many light-years away. They found that colors were more intense under drier conditions. So life might show up better on a planet like Mars than one like Earth.

But they found that large enough patches of many of the organisms could be easy to see whether it was dry or wet — like algal blooms in Earth’s oceans. So to find evidence of extraterrestrial life, future telescopes may look for the color.
 

Script by Damond Benningfield

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The movies often depict the asteroid belt as a danger zone. Space rocks large and small are always just ahead, ready to smash intruding spaceships.

Fortunately, the reality is much calmer. More than a dozen spacecraft have flown into or through the belt, all with no problems — and another is scheduled to head that way early next month.

The first craft to enter the belt did so 50 years ago today.

Pioneer 10 was headed for Jupiter, the solar system’s largest planet. But it had to transit the asteroid belt to get there. The belt is a wide zone between Mars and Jupiter. It contains countless chunks of ice and rock. The largest is about 600 miles in diameter, while the smallest are the size of grains of sand. Astronomers have cataloged more than a million members.

In 1972, though, the number of confirmed asteroids was only in the hundreds, so no one knew what to expect. Most thought Pioneer would get a few small dings, but no big whacks. And in fact, it didn’t even get that many dings. It recorded only a few hits during its seven-month trip through the belt — fewer than expected. It showed that the movies had it all wrong — big space rocks aren’t a constant danger on a trip through the asteroid belt.

Later, Pioneer 10 became the first craft to fly past Jupiter, then to leave the realm of the planets. Today, the dead craft is headed in the direction of Aldebaran, the eye of the bull. It’ll pass the star in about two million years.
 

Script by Damond Benningfield

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