Category Archives: Astronomy

Astronomy, Exoplanets

Hubble makes first observation of helium in the atmosphere of an exoplanet

Observations of planets around other stars continue to produce a steady stream of “firsts”:

Hubble Detects Helium in the Atmosphere of an Exoplanet for the First Time

Exoplanet WASP-107b is one of the lowest density planets known. While the planet is about the same size as Jupiter, it has only 12 percent of Jupiter’s mass. The exoplanet is about 200 light-years from Earth and takes less than six days to orbit its host star. Using infrared spectroscopy, scientists using NASA’s Hubble Space Telescope were able to find helium in the escaping atmosphere of the planet — the first detection of this element in the atmosphere of an exoplanet. [Artist’s rendering of WASP-107b transiting its star.]
Astronomers using NASA’s Hubble Space Telescope have detected helium in the atmosphere of the exoplanet WASP-107b. This is the first time this element has been detected in the atmosphere of a planet outside the solar system. The discovery demonstrates the ability to use infrared spectra to study exoplanet extended atmospheres.

The international team of astronomers, led by Jessica Spake, a PhD student at the University of Exeter in the UK, used Hubble’s Wide Field Camera 3 to discover helium in the atmosphere of the exoplanet WASP-107b. This is the first detection of its kind.

Spake explained the importance of the discovery:

“Helium is the second-most common element in the universe after hydrogen. It is also one of the main constituents of the planets Jupiter and Saturn in our solar system. However, up until now helium had not been detected on exoplanets — despite searches for it.”

The team made the detection by analyzing the infrared spectrum of the atmosphere of WASP-107b. Previous detections of extended exoplanet atmospheres have been made by studying the spectrum at ultraviolet and optical wavelengths; this detection therefore demonstrates that exoplanet atmospheres can also be studied at longer wavelengths.

The measurement of an exoplanet’s atmosphere is performed when the planet passes in front of its host star. A tiny portion of the star’s light passes through the exoplanet’s atmosphere, leaving detectable fingerprints in the spectrum of the star. The larger the amount of an element present in the atmosphere, the easier the detection becomes.

“The strong signal from helium we measured demonstrates a new technique to study upper layers of exoplanet atmospheres in a wider range of planets,” said Spake. “Current methods, which use ultraviolet light, are limited to the closest exoplanets. We know there is helium in the Earth’s upper atmosphere and this new technique may help us to detect atmospheres around Earth-sized exoplanets — which is very difficult with current technology.”

WASP-107b is one of the lowest density planets known: While the planet is about the same size as Jupiter, it has only 12 percent of Jupiter’s mass. The exoplanet is about 200 light-years from Earth and takes less than six days to orbit its host star.

The amount of helium detected in the atmosphere of WASP-107b is so large that its upper atmosphere must extend tens of thousands of miles out into space. This also makes it the first time that an extended atmosphere has been discovered at infrared wavelengths.

Since its atmosphere is so extended, the planet is losing a significant amount of its atmospheric gases into space — between about 0.1 percent to 4 percent of its atmosphere’s total mass every billion years.

Stellar radiation has a significant effect on the rate at which a planet’s atmosphere escapes. The star WASP-107 is highly active, supporting the atmospheric loss. As the atmosphere absorbs radiation it heats up, so the gas rapidly expands and escapes more quickly into space.

As far back as the year 2000, it was predicted that helium would be one of the most readily-detectable gases on giant exoplanets, but until now, searches were unsuccessful.

David Sing, co-author of the study also from the University of Exeter, concluded:

“Our new method, along with future telescopes such as NASA’s James Webb Space Telescope, will allow us to analyze atmospheres of exoplanets in far greater detail than ever before.”

The team’s study appears on May 2, 2018, in the online issue of science journal Nature.

Astronomy

Videos: Night sky highlights for May 2018

NASA JPL provides a list of the top sights in the night sky for May:

See also the Hubble Space Telescope Institute‘s May 2018 night sky preview:

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Asteroids & Comets, Astronomy, Space Science

New animation of Rosetta images shows a wild time on Comet 67P

In 2014 the European Space Agency’s Rosetta probe went into orbit around  Comet 67P/Churyumov–Gerasimenko and spent a couple of years studying it.  Jacint Roger Perez combined a series of 33 images made during a 25 minute period as the probe flew about 13 kilometers from the comet and the resulting time lapse creates the dramatic scene below:

Gif animation created by Jacint Roger Perez from Rosetta images of Comet 67P.

Although it looks like a blizzard, the white dots and streaks are a mix of stars in the dark background plus dust and ice particles,  as well as radiation going through the imager. The comet’s surface at the time was stirred up from the heat of the sun.

More about the animation and the Rossetta mission:

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Astronomy

ESO: Ancient galactic megamergers observed

The latest report from ESO (European Southern Observatory);

Ancient Galaxy Megamergers 

This artist’’s impression of SPT2349-56 shows a group of interacting and merging galaxies in the early Universe. Such mergers have been spotted using the ALMA and APEX telescopes and represent the formation of galaxies clusters, the most massive objects in the modern Universe. Astronomers thought that these events occurred around three billion years after the Big Bang, so they were surprised when the new observations revealed them happening when the Universe was only half that age! [Higher-res images]

The ALMA and APEX telescopes have peered deep into space — back to the time when the Universe was one tenth of its current age — and witnessed the beginnings of gargantuan cosmic pileups: the impending collisions of young, starburst galaxies. Astronomers thought that these events occurred around three billion years after the Big Bang, so they were surprised when the new observations revealed them happening when the Universe was only half that age! These ancient systems of galaxies are thought to be building the most massive structures in the known Universe: galaxy clusters.

Using the Atacama Large Millimeter/submillimeter Array (ALMA) and the Atacama Pathfinder Experiment (APEX), two international teams of scientists led by Tim Miller from Dalhousie University in Canada and Yale University in the US and Iván Oteo from the University of Edinburgh, United Kingdom, have uncovered startlingly dense concentrations of galaxies that are poised to merge, forming the cores of what will eventually become colossal galaxy clusters.

Peering 90% of the way across the observable Universe, the Miller team observed a galaxy protocluster named SPT2349-56. The light from this object began travelling to us when the Universe was about a tenth of its current age.

The individual galaxies in this dense cosmic pileup are starburst galaxies and the concentration of vigorous star formation in such a compact region makes this by far the most active region ever observed in the young Universe. Thousands of stars are born there every year, compared to just one in our own Milky Way.

This montage shows three views of a distant group of interacting and merging galaxies in the early Universe. The left image is a wide view from the South Pole Telescope that reveals just a bright spot. The central view is from Atacama Pathfinder Experiment (APEX) that reveals more details. The right picture is from the Atacama Large Millimeter/submillimeter Array (ALMA) and reveals that the object is actually a group of 14 merging galaxies in the process of forming a galaxy cluster. [Higher-res images]

The Oteo team discovered a similar megamerger formed by ten dusty star-forming galaxies, nicknamed a “dusty red core” because of its very red colour, by combining observations from ALMA and the APEX.

Iván Oteo explains why these objects are unexpected:

“The lifetime of dusty starbursts is thought to be relatively short, because they consume their gas at an extraordinary rate. At any time, in any corner of the Universe, these galaxies are usually in the minority. So, finding numerous dusty starbursts shining at the same time like this is very puzzling, and something that we still need to understand.”

These forming galaxy clusters were first spotted as faint smudges of light, using the South Pole Telescope and the Herschel Space Observatory. Subsequent ALMA and APEX observations showed that they had unusual structure and confirmed that their light originated much earlier than expected — only 1.5 billion years after the Big Bang.

The new high-resolution ALMA observations finally revealed that the two faint glows are not single objects, but are actually composed of fourteen and ten individual massive galaxies respectively, each within a radius comparable to the distance between the Milky Way and the neighbouring Magellanic Clouds.

“These discoveries by ALMA are only the tip of the iceberg. Additional observations with the APEX telescope show that the real number of star-forming galaxies is likely even three times higher. Ongoing observations with the MUSE instrument on ESO’s VLT are also identifying additional galaxies,”

comments Carlos De Breuck, ESO astronomer.

Current theoretical and computer models suggest that protoclusters as massive as these should have taken much longer to evolve. By using data from ALMA, with its superior resolution and sensitivity, as input to sophisticated computer simulations, the researchers are able to study cluster formation less than 1.5 billion years after the Big Bang.

“How this assembly of galaxies got so big so fast is a mystery. It wasn’t built up gradually over billions of years, as astronomers might expect. This discovery provides a great opportunity to study how massive galaxies came together to build enormous galaxy clusters,” 

says Tim Miller, a PhD candidate at Yale University and lead author of one of the papers.

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Astronomy, Space Arts

A multi-colored Blue Horsehead Nebula

NASA’s Astronomy Picture of the Day (APOD) for April 23rd is more painterly than usual:

“The Blue Horsehead Nebula in Infrared”. Image Credit: WISE, IRSA, NASA; Processing & Copyright : Francesco Antonucci

Note that processing of an infrared image allows for considerable freedom in how the final rendering appears. In this case, it was rendered with great artistry by Mr. Antonucci.

From the caption:

The Blue Horsehead Nebula looks quite different in infrared light. In visible light, the reflecting dust of the nebula appears blue and shaped like a horse’s head. In infrared light, however, a complex labyrinth of filaments, caverns, and cocoons of glowing dust and gas emerges, making it hard to even identify the equine icon. The featured image of the nebula was created in three infrared colors (R=22, G=12, B=4.6 microns) from data taken by NASA’s orbiting Wide Field Infrared Survey Explorer (WISE) spacecraft. The nebula is cataloged as IC 4592 and spans about 40 light years, lying about 400 light years away toward the constellation Scorpius along the plane of our Milky Way Galaxy. IC 4592 is fainter but covers an angularly greater region than the better known Horsehead Nebula of Orion. The star that predominantly illuminates and heats the dust is Nu Scorpii, visible as the yellow star left of center.

 

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