Tag: James Webb Space telescope (page 2 of 2)

Shredding Exoplanets, And The Mysteries They May Unravel

In this artist’s conception, a tiny rocky object vaporizes as it orbits a white dwarf star. Astronomers have detected the first planetary object transiting a white dwarf using data from the K2 mission. Slowly the object will disintegrate, leaving a dusting of metals on the surface of the star. (NASA)

In this artist’s conception, a small planet or planetesimal vaporizes as it orbits close to a white dwarf star. The detection of several of these disintegrating planets around a variety of stars has led some astronomers to propose intensive study of their ensuing dust clouds as a surprising new way to learn about the interiors of  exoplanet.  (NASA)

One of the seemingly quixotic goals of exoplanet scientists is to understand the chemical and geo-chemical compositions of the interiors of the distant planets they are finding.   Learning whether a planet is largely made up of silicon or magnesium or iron-based compounds is essential to some day determining how and where specific exoplanets were formed in their solar systems, which ones might have the compounds and minerals believed to be necessary for  life, and ultimately which might actually be hosting life.

Studying exoplanet interiors is a daunting challenge for sure, maybe even more difficult in principle than understanding the compositions of exoplanet atmospheres.  After all, there’s still a lot we don’t know about the make-up of planet interiors in our own solar system.

An intriguing pathway, however, has been proposed based on the recent discovery of exoplanets in the process of being shredded.  Generally orbiting very close to their suns, they appear to be disintegrating due to intense radiation and the forces of gravity.

And the result of their coming apart is that their interiors, or at least the dust clouds from their crusts and mantles, may well be on display and potentially measurable.

“We know very little for sure about these disintegrating planets, but they certainly seem to offer a real opportunity,” said Jason Wright, an astrophysicist at Pennsylvania State University with a specialty in stellar astrophysics.  No intensive study of the dusty innards of a distant, falling-apart exoplanet has been done so far,  he said, but in theory at least it seems to be possible.

Artist’s impression of disintegrating exoplanet KIC 12255 (C.U Keller, Leiden University)

Artist’s impression of disintegrating exoplanet KIC 12557548, the first of its kind ever detected. (C.U Keller, Leiden University)

And if successful, the approach could prove broadly useful since astronomers have already found at least four of disintegrating planets and predict that there are many more out there.  The prediction is based on, among other things, the relative speed with which the planets fall apart.  Since the disintegration has been determined to take only tens of thousands to a million years (a very short time in astronomical terms) then scientists conclude that the shreddings must be pretty common  –based on the number already caught in the act.… Read more

How Will We Know What Exoplanets Look Like, and When?

An earlier version of this article was accidently published last week before it was completed.  This is the finished version, with information from this week’s AAS annual conference.

This image of a pair of interacting galaxies called Arp 273 was released to celebrate the 21st anniversary of the launch of the NASA/ESA Hubble Space Telescope. The distorted shape of the larger of the two galaxies shows signs of tidal interactions with the smaller of the two. It is thought that the smaller galaxy has actually passed through the larger one.

This image of a pair of interacting galaxies called Arp 273 was released to celebrate the 21st anniversary of the launch of the NASA/ESA Hubble Space Telescope. The distorted shape of the larger of the two galaxies shows signs of tidal interactions with the smaller of the two. It is thought that the smaller galaxy has actually passed through the larger one.

Let’s face it:  the field of exoplanets has a significant deficit when it comes to producing drop-dead beautiful pictures.

We all know why.  Exoplanets are just too small to directly image, other than as a miniscule fraction of a pixel, or perhaps some day as a full pixel.  That leaves it up to artists, modelers and the travel poster-makers of the Jet Propulsion Lab to help the public to visualize what exoplanets might be like.  Given the dramatic successes of the Hubble Space Telescope in imaging distant galaxies, and of telescopes like those on the Cassini mission to Saturn and the Mars Reconnaissance Orbiter, this is no small competitive disadvantage.  And this explains why the first picture of this column has nothing to do with exoplanets (though billions of them are no doubt hidden in the image somewhere.)

The problem is all too apparent in these two images of Pluto — one taken by the Hubble and the other by New Horizons telescope as the satellite zipped by.

 

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Pluto image taken by Hubble Space Telescope (above) and close up taken by New Horizons in 2015. (NASA)

Pluto image taken by Hubble Space Telescope (above) and close up taken by New Horizons in 2015. (NASA)

 

Pluto is about 4.7 billion miles away.  The nearest star, and as a result the nearest possible planet, is 25 trillion miles  away.  Putting aside for a minute the very difficult problem of blocking out the overwhelming luminosity of a star being cross by the orbiting planet you want to image,  you still have an enormous challenge in terms of resolving an image from that far away.

While current detection methods have been successful in confirming more than 2,000 exoplanets in the past 20 years (with another 2,000-plus candidates awaiting confirmation or rejection),  they have been extremely limited in terms of actually producing images of those planetary fireflies in very distant headlights.  And absent direct images — or more precisely, light from those planets — the amount of information gleaned about the chemical makeup of their atmospheres  as been limited, too.… Read more

Faint Worlds On the Far Horizon

Faintest distant galaxy ever detected, formed only 400 million years after the Big Bang. NASA, ESA, and L. Infante (Pontificia Universidad Catolica de Chile)

Faintest distant galaxy ever detected, formed only 400 million years after the Big Bang. NASA, ESA, and L. Infante (Pontificia Universidad Catolica de Chile)

For thinking about the enormity of the canvas of potential suns and exoplanets, I find images like this and what they tell us to be an awkward combination of fascinating and daunting.

This is an image that, using the combined capabilities of NASA’s Hubble and Spitzer space telescopes, shows what is being described as the faintest object, and one of very oldest, ever seen in the early universe.  It is a small, low mass, low luminosity and low size proto-galaxy as it existed some 13.4 billion years ago, about 4oo million years after the big bang.

The team has nicknamed the object Tayna, which means “first-born” in Aymara, a language spoken in the Andes and Altiplano regions of South America.

Though Hubble and Spitzer have detected other galaxies that appear to be slightly further away, and thus older, Tayna represents a smaller, fainter class of newly forming galaxies that until now have largely evaded detection. These very dim bodies may offer new insight into the formation and evolution of the first galaxies — the “lighting of the universe” that occurred after several hundred million years of darkness following the big bang and its subsequent explosion of energy.

This is an illustration by Adolf Schaller from the Hubble Gallery (NASA). It is public domain. It shows colliding protogalaxies less than 1 billion years afer the big bang.

This is an illustration by Adolf Schaller from the Hubble Gallery and shows
colliding protogalaxies less than 1 billion years after the big bang. (NASA)

Detecting and trying to understand these earliest galaxies is somewhat like the drive of paleo-anthropologists to find older and older fossil examples of early man. Each older specimen provides insight into the evolutionary process that created us, just as each discovery of an older, or less developed, early galaxy helps tease out some of the hows and whys of the formation of the universe.

Leopoldo Infante, an astronomer at Pontifical Catholic University of Chile, is the lead author of last week’s Astrophysical Journal article on the faintest early galaxy.  He said there is good reason to conclude there were many more of these earliest proto-galaxies than the larger ones at the time, and that they were key in the “reionization” of the universe — the process through which the universe’s early “dark ages” were gradually ended by the formation of more and more luminous stars and galaxies..

But the process of detecting these very early proto-galaxies is only beginning, he said, and will pick up real speed only when the NASA’s James Webb Space Telescope (scheduled to be launched in 2018) is up and operating. … Read more

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