A new finding by the Hubble Telescope:

Hubble observes exoplanet atmosphere in more detail than ever before

An international team of scientists has used the NASA/ESA Hubble Space Telescope to study the atmosphere of the hot exoplanet WASP-39b. By combining this new data with older data they created the most complete study yet of an exoplanet atmosphere. The atmospheric composition of WASP-39b hints that the formation processes of exoplanets can be very different from those of our own Solar System giants.

Investigating exoplanet atmospheres can provide new insight into how and where planets form around a star.

“We need to look outward to help us understand our own Solar System,” 

explains lead investigator Hannah Wakeford from the University of Exeter in the UK and the Space Telescope Science Institute in the USA.

Therefore the British-American team combined the capabilities of the NASA/ESA Hubble Space Telescope with those of other ground- and space-based telescopes for a detailed study of the exoplanet WASP-39b. They have produced the most complete spectrum of an exoplanet’s atmosphere possible with present-day technology [1].

WASP-39b is orbiting a Sun-like star, about 700 light-years from Earth. The exoplanet is classified as a “Hot-Saturn”, reflecting both its mass being similar to the planet Saturn in our own Solar System and its proximity to its parent star. This study found that the two planets, despite having a similar mass, are profoundly different in many ways. Not only is WASP-39b not known to have a ring system, it also has a puffy atmosphere that is free of high-altitude clouds. This characteristic allowed Hubble to peer deep into its atmosphere.

By dissecting starlight filtering through the planet’s atmosphere [2] the team found clear evidence for atmospheric water vapour. In fact, WASP-39b has three times as much water as Saturn does. Although the researchers had predicted they would see water vapour, they were surprised by the amount that they found. This surprise, combined with the water abundance allowed to infer the presence of large amount of heavier elements in the atmosphere. This in turn suggests that the planet was bombarded by a lot of icy material which gathered in its atmosphere. This kind of bombardment would only be possible if WASP-39b formed much further away from its host star than it is right now.

“WASP-39b shows exoplanets are full of surprises and can have very different compositions than those of our Solar System,” 

says co-author David Sing from the University of Exeter, UK.

The analysis of the atmospheric composition and the current position of the planet indicate that WASP-39b most likely underwent an interesting inward migration, making an epic journey across its planetary system.

 “Exoplanets are showing us that planet formation is more complicated and more confusing than we thought it was. And that’s fantastic!”,

adds Wakeford.

Having made its incredible inward journey WASP-39b is now eight times closer to its parent star, WASP-39, than Mercury is to the Sun and it takes only four days to complete an orbit. The planet is also tidally locked, meaning it always shows the same side to its star. Wakeford and her team measured the temperature of WASP-39b to be a scorching 750 degrees Celsius. Although only one side of the planet faces its parent star, powerful winds transport heat from the bright side around the planet, keeping the dark side almost as hot.

“Hopefully this diversity we see in exoplanets will help us figure out all the different ways a planet can form and evolve,”

explains David Sing.

Looking ahead, the team wants to use the NASA/ESA/CSA James Webb Space Telescope — scheduled to launch in 2019 — to capture an even more complete spectrum of the atmosphere of WASP-39b. James Webb will be able to collect data about the planet’s atmospheric carbon, which absorbs light of longer wavelengths than Hubble can see [3]. Wakeford concludes:

“By calculating the amount of carbon and oxygen in the atmosphere, we can learn even more about where and how this planet formed.”

Notes

[1] Data used to produce the full spectrum was also collected by NASA’s Spitzer Space Telescope and ESO’s Very Large Telescope. In addition older data from Hubble were used.

[2] When starlight passes through the atmosphere of an exoplanet, it interacts with the atoms and molecules in it. This leaves a weak fingerprint of the atmosphere in the spectrum of the star. Certain peaks and troughs in the resulting spectrum correspond to specific atoms and molecules, allowing scientists to see exactly what gases make up the atmosphere.

[3] Given the large amount of heavy elements in WASP-39b’s atmosphere, Wakeford and her team predict that carbon dioxide will be the dominant form of carbon. This could be measured at a wavelength of 4.5 micrometres with James Webb’s NIRSpec instrument. Such follow-up investigations would allow further constraints to be placed on the ratio of carbon to oxygen, and on the metallicity of WASP-39b’s atmosphere.

Here is NASA JPL’s latest preview of the night sky for the coming month:

And here is the Hubble Institute‘s:

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Here is the NASA JPL “What’s Up for February 2018” astronomy highlights:

And here is the Hubble space telescope institute’s latest “Tonight’s Sky”:

Speaking of space telescopes, here is a recent public talk about the huge James Webb Space Telescope, which is to launch in 2019:

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The latest report from the ESO (European Southern Observatory):

Glory From Gloom

A dark cloud of cosmic dust snakes across this spectacular wide field image, illuminated by the brilliant light of new stars. This dense cloud is a star-forming region called Lupus 3, where dazzlingly hot stars are born from collapsing masses of gas and dust. This image was created from images taken using the VLT Survey Telescope and the MPG/ESO 2.2-metre telescope and is the most detailed image taken so far of this region.

In the star-forming region Lupus 3, in the constellation of Scorpius (The Scorpion), dazzlingly hot stars are born from collapsing masses of gas and dust. This short podcast showcases a new picture of this dramatic object, created from images taken using the VLT Survey Telescope and the MPG/ESO 2.2-metre telescope at ESO’s La Silla Observatory in Chile. It is the most detailed image taken so far of this region.

The Lupus 3 star forming region lies within the constellation of Scorpius (The Scorpion), only 600 light-years away from Earth. It is part of a larger complex called the Lupus Clouds, which takes its name from the adjacent constellation of Lupus(The Wolf). The clouds resemble smoke billowing across a background of millions of stars, but in fact these clouds are a dark nebula.

Nebulae are great swathes of gas and dust strung out between the stars, sometimes stretching out over hundreds of light-years. While many nebulae are spectacularly illuminated by the intense radiation of hot stars, dark nebulae shroud the light of the celestial objects within them. They are also known as absorption nebulae, because they are made up of cold, dense particles of dust that absorb and scatter light as it passes through the cloud.

Famous dark nebulae include the Coalsack Nebula and the Great Rift, which are large enough to be seen with the naked eye, starkly black against the brilliance of the Milky Way.

This zoom sequence starts with a view of the central parts of the Milky Way. We close in on a region in the constellation of Scorpius (The Scorpion). The final view is a combined image from data from both the VLT Survey Telescope and the MPG/ESO 2.2-metre telescope at the La Silla Observatory in Chile. It shows a dark cloud where new stars are forming along with a cluster of brilliant stars that have already burst out of their dusty stellar nursery. This cloud is known as Lupus 3 and it lies about 600 light-years from Earth. It is likely that the Sun formed in a similar star formation region more than four billion years ago. Credit: ESO/R. Colombari/Digitized Sky Survey 2/N. Risinger (skysurvey.org). Music: Astral electronic.

Lupus 3 has an irregular form, appearing like a misshapen snake across the sky. In this image it is a region of contrasts, with thick dark trails set against the glare of bright blue stars at the centre. Like most dark nebulae, Lupus 3 is an active star formation region, primarily composed of protostars and very young stars. Nearby disturbances can cause denser clumps of the nebula to contract under gravity, becoming hot and pressurised in the process. Eventually, a protostar is born out of the extreme conditions in the core of this collapsing cloud.

The two brilliant stars in the centre of this image underwent this very process. Early in their lives, the radiation they emitted was largely blocked by the thick veil of their host nebula, visible only to telescopes at infrared and radio wavelengths. But as they grew hotter and brighter, their intense radiation and strong stellar winds swept the surrounding areas clear of gas and dust, allowing them to emerge gloriously from their gloomy nursery to shine brightly.

These two stars are still very young — so young that nuclear fusion has not yet been triggered in their cores. Instead, their brightness is caused by the conversion of gravitational energy into heat as their turbulent cores contract.

Understanding nebulae is critical for understanding the processes of star formation — indeed, it is thought that the Sun formed in a star formation region very similar to Lupus 3 over four billion years ago. As one of the closest stellar nurseries, Lupus 3 has been the subject of many studies; in 2013, the MPG/ESO 2.2-metre telescope at ESO’s La Silla Observatoryin Chile captured a smaller picture of its dark smoke-like columns and brilliant stars (eso1303).

Links

• Research review paper
• Photos of the VLT Survey Telescope
• Photos of the MPG/ESO 2.2-metre telescope

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