Unit 3 neighbours in the sky

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Reflected Heat Reveals Hiding Planets

Two independent teams of astronomers – one headed by Drake Deming of the Goddard Space Flight Center, the other – by David Charbonneau of the Harvard-Smithsonian Center for Astrophysics – have for the first time detected the heat glow of platens circling distant stars.

Both teams used the data provided by the infrared Spitzer Space Telescope and the same methods to measure the heat glow of the planets. First, the astronomers acquired a picture of both the star and the planet, then discerned the heat glow of the star (at the moment when the planet was behind it), thus calculating the portion of heat radiated by the planet only.

Deming's team focused on the planet designated as HD 209458b, which circles a star about 153 light-years away from Earth, while Char-bonneau's team observed the heat glow of a planet called TrES-i, the distance to which is more than three times larger. Both stars resemb­le the Sun by their parame­ters.

The two planets were dis­covered in 1999 and 2004 in an indirect way – their exis­tence was inferred from slight fluctuations of star shine in the visible range of radiation. Having now de­tected infrared radiation of the planets, the scientists cal­culated their temperatures – 857 and 788 degrees Celsius (HD 209458b and TrES-i,

respectively). Considering the giant size of the planets, the astronomers described them as "hot Jupiters".

Both gas giants move rela­tively close to their parent stars. Thus, TrES-i is only 6.4 million km away from its star (for comparison, the dis­tance between the Sun and Earth is more than 23 times larger). By the way, TrES-i reflects 31 percent of light that falls on it; no wonder that it is so hot;

As for HD 269458b, it is interesting in another way. It actually posed a theoretical puzzle before scientists. Taking the weight of this gas giant into account, the planet is too large, "overblown". Astronomers suspect this to be a result of the influence of some other, closely lying planet that hasn't been dis­covered yet.

It should be explained why the infrared frequencies of the spectrum have drawn such close attention of two scientific teams. The reason is that giant planets that cir­cle closely to their parent stars are only 400-fold dim­mer (in the infrared range) than the stars themselves, while in the visible range, the stars, are 10,000 times brighter. The planets literal­ly get lost in the glitter of their parent stars.

Astronomers already know 130 stars with planets or even planet systems discov­ered around them that resemble ours in some way or other.

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For fun

An Almost Sci-Fi Story

The harvest season was in full swing, everyone was busy with the earth, not with the sky. But the sky, as ill or good luck would have it, was bright blue, clear and empty, so that when a sizeable object appeared in it all raised their heads.

The object had the shape of a flat disc and seemed to be transparent in the middle; it bore some resem­blance to a jellyfish, if anyone had ever looked up at a jellyfish from under the water; or else it could have been best compared to the seed-head of a dandelion, somewhat flattened. Imagine picking a dandelion and blowing at it to make all the fluff scatter, but it doesn't and the dandelion just flies up high and there, at a great height, grows to an enormous size and then be­gins to descend again – that would provide exactly the same picture.

The object continued to grow in size and the alarm of those looking up at it grew correspondingly: what if it covered the whole field or the whole neighbor­hood, or the whole hemisphere? But their alarm was so vague that they could not decide whether or not to seek safety in running away.

The team leader, Filipp Semyonovich, his arms akimbo, looked up together with everyone else, then, his head still raised skyward, he beckoned with a masterly gesture to his assistant and commanded curtly as a surgeon: "Volodya, off to the village at a run. Bring back bread, salt and a towel... Double-quick!"

Volodya disappeared, and when he materialized again the object had announced its presence not only to the eyes but also to the ears by high-pitched sound; the local accordionist maintained later that it was the melody of a popular song, Felt Boots.

In the meantime the object descended so low that one could make out a pattern on its underbelly. Later it became clear that that was no idle decoration but a network of tubes. Then the music died down and the apparatus, which turned out to be the size of a pedi­gree bull, settled onto the plowed field.

The team leader, Filipp Semyonovich, took the towel, bread and salt from Volodya and command­ed:

"Follow me, everybody. In proper order! No push­ing!" Upon which he moved toward the fluff-retain­ing dandelion, or jellyfish, the size of a pedigree bull.

In the meantime two creatures emerged from the belly of the jellyfish. Needless to say, they were wear­ing spacesuits. They were of medium height, but of infant-like proportions – a huge head under the glass dome, the body laced into a corset made of some­thing like a boa-constrictor, and short, but it seemed, jointed legs which allowed the creatures to make fast, mincing steps over the soft plowed soil. The crea­tures waved their upper limbs which had fingers grow­ing apparently from the elbows, each digit about half a meter in length; It was with these limbs that the unexpected arrivals were waving.

"They've got grabbing hands for sure!" Filipp Se­myonovich muttered to himself, while the bread in his hands shook slightly and a bit of salt spilt out of the saltcellar; but Filipp Semyonovich did not notice it

In the meantime the creatures had spread out a sort of map and were gesticulating in evident vexa­tion, that is if their emotions were in any degree sim­ilar to ours.

Finally they quietened down and stared at the approaching crowd headed by the team leader. Some­thing like hope showed in their disappointed faces. And when Filipp Semyonovich, pale but full of dig­nity, opened his mouth to shout in a strained voice: "Welcome to you, dear guests!" he was stopped by the comprehensible gesture of an outstretched wav­ing cosmic palm.

The creature who had waved pressed a button on his suit, switching on a portable microphone from which issued in impeccable accents of the local dia­lect:

"You didn't come across a spade somewhere here­abouts by any chance?"

The reporter's microphone was then pushed un­der Filipp Semyonovich's nose.

"What spade?" the bewildered team leader mum­bled.

"You see, 700 million years, 11 months, 4 days, 5 hours, and 48 minutes ago our people visited this planet with the aim of replenishing our Andromeda menagerie with diplodoci. Mission accomplished, it was noticed before the takeoff — exactly from this spot — that one of the apparatus wheels had got stuck in the mud. The wheel was eventually extricated by means of a spade, but when they returned home the auditing commission established that some scatter-brain had left the spade behind, on your' planet They failed to identify the culprit because during the time of the flight eighty generations had succeeded one other. Anyway it was necessary to return here ur­gently to retrieve the public property. Thanks to our ancestors, eighty generations removed, this honor­able task fell to our lot. So you haven't chanced upon a spade?"

"A spade?" Filipp Semyonovich asked once again in a horrified voice. "But we have plenty of spades... Volodya," he addressed his assistant, "run to the ware­house and bring a couple of the newest."

"Certainly not!" a hurried voice sounded from the microphone. "Wouldn't hear of it. We need that par­ticular spade. It bears a stamp. It's an inventory item. It all happened precisely here, the calculations are exact, yet there is no spade... Bad luck."

Filipp Semyonovich looked at the visitors with a fatherly concern. "Let Volodya bring you the spades, they're just as good to dig with as any, it's no more than half an hour from here to the warehouse at a trot."

"Oh no, that will never do," the microphone re­plied sadly. "It's either that particular spade or none at all. We have a single-task program. Have to make an empty run back now. Well... what chance did we have of finding it?"

"And what will they do about it now?" Filipp Se­myonovich asked compassionately. - "A court trial," the microphone said. "Not that it is our worry. We've done our duty. It's our descen­dants, eighty generations removed, who'll have to answer for it..."

The creature switched off, and together with his male (or female) companion climbed back into the belly of the jellyfish.

Both of them waved hands again in farewell and smoothly took off.

There was more music, but not so cheerful as at their landing. The local accordionist maintained later that it was the popular song Lost Among the Tall Wheat.

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