Stars Are The Universe’s Neat Freaks

The Andromeda Galaxy, viewed using conventional optics and IR. Credit: Kitt Peak National Observatory

Imagine, if you will, that the Universe was once a much dirtier place than it is today. Imagine also that what we see around us, a relatively clean and unobscured Universe, is the result of billions of years of stars behaving like giant celestial Roombas, cleaning up the space around them in preparation for our arrival. According to a set of recently published catalogues, which detail the latest findings from the ESA’s Herschel Space Observatory, this description is actually quite fitting.

These catalogues represents the work of an international team of over 100 astronomers who have spent the past seven years analyzing the infrared images taken by the Herschel Astrophysical Terahertz Large Area Survey (Herschel-ATLAS). Presented earlier this week at the National Astronomy Meeting in Nottingham, this catalogue revealed that as early as 1 billion years ago, the Universe looked much different than it does today.

In order to put this research into context, it is important to understand the important of infrared astronomy. Prior to the deployment of missions like Herschel (which was launched in 2009), astronomers were unable to see a good portion of the light emitted by stars and galaxies. With roughly half of this light being absorbed by interstellar dust grains, research into the birth and lives of galaxies was difficult.

But thanks to surveys like Herschel ATLAS – as well NASA’s Spitzer Space Telescope and the Wide-field Infrared Survey Explorer (WISE) – astronomers have been able to account for this missing energy. And what they have seen (especially from this latest survey) has been quite remarkable, presenting a Universe that is far denser than previously expected.

Last week (Friday, June 29th), during the final day of the National Astronomy Meeting, the first of the catalogues was presented. The images they showed gave all those present a glimpse of the unseen stars and galaxies that have existed over the last 12 billion years of cosmic history. In sum,  over half-a-million far-infrared sources have been spotted by the Herschel-ATLAS survey, and what they revealed was fascinating.

Many of these sources were galaxies that are nearby and similar to our own, and which are detectable using using conventional telescopes. The others were much more distant, their light taking billions of years to reach us, and were obscured by concentrations of cosmic dust. The most distant of these galaxies were roughly 12 billion light-years away, which means that they appeared as they would have 12 billion years ago.

Ergo, astronomers now know that 12 billion years ago (i.e. shortly after the Big Bang)., stars and galaxies were much dustier than they are now. They further concluded that the evolution of our galaxies since shortly after the Big Bang has essentially been a major clean-up effort, as stars gradually absorbed the dust that obscured their light, thus making it the more “visible” place it is today.

The data released by the survey includes several maps and additional files which were described in an article produced by Dr. Elisabetta Valiante and a research team from Cardiff University – titled “The Herschel-ATLAS Data Release 1 Paper I: Maps, Catalogues and Number Counts“. As Dr. Valiante told Universe Today via email:

“Gas and dust are the main components of stars: they collapse to form stars and they are ejected at the end of stars’ life. The interesting thing that has been discovered thanks to the Herschel data is that the two phenomena are not in equilibrium. We knew this was true 10 billion years ago, but we expected, according to the current models, that some equilibrium was reached at more recent times. Instead, the amount of dust in galaxies 5 billion years ago was much larger than the amount we see in galaxies today: this was unexpected.”

Until recently, such a survey would have been impossible due to the fact that many of these infrared sources would have  been invisible to astronomers. The reason for this, which was revealed by the survey, was that these galaxies were so dusty that they would have been virtually impossible to detect with conventional optics. What’s more, their light would have been gravitationally magnified by intervening galaxies.

The huge size of the survey has also meant that changes that have occurred in galaxies – relatively recent in cosmic history – can be studied for the first time. For instance, the survey showed that even only one billion years in the past, a small fraction of the age of the universe, galaxies were forming stars at a faster rate and contained more dust than they do today.

Dr. Nathan Bourne – from the University of Edinburgh – is the lead author of another other paper describing the catalogues. As he told Universe Today via email:

“We can think of galaxies as big recycling machines. When they form, they accrete gas (mostly hydrogen and helium, with traces of lithium and a couple of other elements) from the universe around them, and they turn it into stars. As time goes on, the stars pump this gas back out into the galaxy, into the interstellar medium. Due to the nuclear processes within the stars, the gas is now enriched by heavy elements (what we call metals, though they include both metals and non-metals), and some of these form microscopic solid particles of dust, as a sort of by-product.

“But there are still stars forming, and the next generations of stars recycle this interstellar material, and now that it contains heavy elements and dust, things are a bit different, and planets can also form around the new stars, from accumulations of this heavy material. So, if you look at the big picture, when the first galaxies started forming within the first billion years after the Big Bang, they began using up the gas around them, and then while they are active they fill their interstellar medium up with gas and dust, but by the end of a galaxy’s lifecycle, it has used up all this gas and dust, and you could say that it has cleaned itself.”

The catalogues and maps of the hidden universe are a triumph for the Herschel team. Despite the fact that the last information obtained by the Herschel observatory was back in 2013, the maps and catalogues produced from its years of service have become vital to astronomers. In addition to showing the Universe’s hidden energy, they are also laying the groundwork for future research.

“Now we need to explain why there is dust where we did not expect to find it.” said Valiante. “And to explain this, we need to change our theories about how the Universe evolves. Our data poses a challenge we have accepted, but we haven’t overcome it yet!”

“[W]e understand a lot more about how galaxies evolve,” added Bourne, “about when most of the stars formed, what happens to the gas and dust as galaxies evolve, and how rapidly the star-forming activity in the Universe as a whole has faded in the latter half of the Universe’s history. It’s fair to say that this understanding comes from having a whole suite of different types of instruments studying different aspects of galaxies in complementary ways, but Herschel has certainly contributed a major part of that effort and will have a lasting legacy.”

The implications of these findings are also likely to have a far-reaching effect, ranging from cosmology and astronomy, to perhaps shedding some light on that tricky Fermi paradox. Could it be intelligent life that emerged billions of years ago didn’t venture to other star systems because they couldn’t see them? Just a thought…

This data release from the H-ATLAS team was coordinated with releases made in late June from the Herschel Extragalactic Project (HELP) team and the Herschel Multi-tiered Extragalactic Survey (HerMES). H-ATLAS and HerMES are parts of the EU Research Executive Agency’s HELP program, which brings together various extragalactic surveys carried out by Herschel and combines them with major surveys conducted by other observatories to give the Herschel mission a lasting legacy.

Further Reading: Royal Astronomical Society, ESA

The post Stars Are The Universe’s Neat Freaks appeared first on Universe Today.

Starshade Prepares To Image New Earths

Artist's concept of the prototype starshade, a giant structure designed to block the glare of stars so that future space telescopes can take pictures of planets. Credit: NASA/JPL

For countless generations, people have looked up at the stars and wondered if life exists somewhere out there, perhaps on planets much like ours. But it has only been in recent decades that we have been able to confirm the existence of extrasolar planets (aka. exoplanets) in other star systems. In fact, between 1988 and April 20th of 2016, astronomers have been able to account for the existence of 2108 planets in 1350 different star systems, including 511 multiple planetary systems.

Most of these discoveries have taken place within just the past three years, thanks to improvements in our detection methods, and the deployment of the Kepler space observatory in 2009. Looking ahead, astronomers hope to improve on these methods even further with the introduction of the Starshade, a giant space structure designed to block the glare of stars, thus making it easier to find planets – and perhaps another Earth!

While some planets have been observed directly with telescopes (a process known as “Direct Imaging”), the vast majority have been detected through indirect methods such as the Transit Method. This method attempts to spot planets as they cross in front of the parent star’s disk – during which time there will be a temporary drop in observed brightness – and can also reveal the radius of a planet and sometimes yield information on its atmosphere (with the help of spectrometers).

https://youtu.be/ALGI0ex0-ac?list=PLTiv_XWHnOZp2Wmmd3gVSiKAVyXk9Rh14

This method remains the most widely-used means of detection and is responsible for more exoplanet discoveries than all other methods combined. However, due to interference from other light sources, it also suffers from a substantial rate of false positives, and generally requires that part of the planet’s orbit intersect a line-of-sight between the host star and Earth.

To address this, NASA is developing some key technologies that will help block out light interference so that future astronomers can detect exoplanets more easily. For instruments here on Earth, they are developing chronographs, single instruments that fit inside telescopes to block light. But looking to space, NASA’s Jet Propulsion Laboratory is also developing the Starshade.

This concept calls for a giant, flower-shaped spacecraft that would be launched with one of NASA’s next-generation space telescopes. Once deployed, it would fly around in front of the telescope in order to obscure the light of distant stars. This way, the light being reflected off of planets in orbit around them will be detectable, thus making it that much easier to confirm the presence of exoplanets.

The project is led by Prof. Jeremy Kasdin of Princeton University, in conjunction with the JPL and support from Northrop Grumman (which leads the mission and system design for Starshade). As Kasdin explained to Universe Today via email:

“The starshade works just like your thumb when trying to block the Sun; it blocks the starlight from entering the telescope but allows light from he planet close by to pass unimpeded.  Since planets are so much dimmer than their host stars, this technology eliminates the problem of glare from the star swamping light from the planet.  And because the starlight never enters the telescope, any conventional telescope can be used; no special attention needs to be paid to stabilities and precision in the telescope.”

https://youtu.be/Hn0VtQ3FqCw

The shade, which is about the  size of a baseball diamond, would be deployed as part a single mission. As the video above shows, the large shade would be mounted at the end of a space telescope – in this case, NASA’s upcoming Wide Field Infrared Survey Telescope (WFIRST) – and then detaches and deploys to a distance of several thousands kilometers in front of it.

Such a large shade operating at such a long distance from of its paired telescope is essential when dealing with distant stars.”Because stars are so far away the angular distance between the planet and star is quite small,” said Kasdin, “requiring a very large starshade (20 to 50 meters in diameter) flying very far from the telescope (up to 50,000 km). Nevertheless, many astronomers believe this is the best technology to detect an Earthlike planet in the near future, a belief aided by the fact that few special requirements are placed on the telescope.”

Paired with other instruments, like spectrometers, devices like the Starshade will not only allow astronomers to be able to spot planets more easily, but also obtain information about their atmospheres. By studying their chemical compositions – i.e. looking for the presence of oxygen/nitrogen, water vapor, etc. – we would be able to tell with a fair degree of certainty whether or not life exists on them.

The Starshade technology is one of the top candidates for a flagship-level mission in the next decade and a top Astro2010 priority for technology development. In addition to working with WFIRST, it is possible it will be paired with missions like the Transiting Exoplanet Survey Satellite (TESS) and the James Webb Space Telescope.

“We are hoping that a starshade capable of Earth detection will be recommended to fly with the upcoming WFIRST mission,” Kasdin added, “allowing the first image of an Earth in the next decade.”

 

Further Reading: JPL News

The post Starshade Prepares To Image New Earths appeared first on Universe Today.

Starshade Prepares To Image New Earths

Artist's concept of the prototype starshade, a giant structure designed to block the glare of stars so that future space telescopes can take pictures of planets. Credit: NASA/JPL

For countless generations, people have looked up at the stars and wondered if life exists somewhere out there, perhaps on planets much like ours. But it has only been in recent decades that we have been able to confirm the existence of extrasolar planets (aka. exoplanets) in other star systems. In fact, between 1988 and April 20th of 2016, astronomers have been able to account for the existence of 2108 planets in 1350 different star systems, including 511 multiple planetary systems.

Most of these discoveries have taken place within just the past three years, thanks to improvements in our detection methods, and the deployment of the Kepler space observatory in 2009. Looking ahead, astronomers hope to improve on these methods even further with the introduction of the Starshade, a giant space structure designed to block the glare of stars, thus making it easier to find planets – and perhaps another Earth!

While some planets have been observed directly with telescopes (a process known as “Direct Imaging”), the vast majority have been detected through indirect methods such as the Transit Method. This method attempts to spot planets as they cross in front of the parent star’s disk – during which time there will be a temporary drop in observed brightness – and can also reveal the radius of a planet and sometimes yield information on its atmosphere (with the help of spectrometers).

https://youtu.be/ALGI0ex0-ac?list=PLTiv_XWHnOZp2Wmmd3gVSiKAVyXk9Rh14

This method remains the most widely-used means of detection and is responsible for more exoplanet discoveries than all other methods combined. However, due to interference from other light sources, it also suffers from a substantial rate of false positives, and generally requires that part of the planet’s orbit intersect a line-of-sight between the host star and Earth.

To address this, NASA is developing some key technologies that will help block out light interference so that future astronomers can detect exoplanets more easily. For instruments here on Earth, they are developing chronographs, single instruments that fit inside telescopes to block light. But looking to space, NASA’s Jet Propulsion Laboratory is also developing the Starshade.

This concept calls for a giant, flower-shaped spacecraft that would be launched with one of NASA’s next-generation space telescopes. Once deployed, it would fly around in front of the telescope in order to obscure the light of distant stars. This way, the light being reflected off of planets in orbit around them will be detectable, thus making it that much easier to confirm the presence of exoplanets.

The project is led by Prof. Jeremy Kasdin of Princeton University, in conjunction with the JPL and support from Northrop Grumman (which leads the mission and system design for Starshade). As Kasdin explained to Universe Today via email:

“The starshade works just like your thumb when trying to block the Sun; it blocks the starlight from entering the telescope but allows light from he planet close by to pass unimpeded.  Since planets are so much dimmer than their host stars, this technology eliminates the problem of glare from the star swamping light from the planet.  And because the starlight never enters the telescope, any conventional telescope can be used; no special attention needs to be paid to stabilities and precision in the telescope.”

https://youtu.be/Hn0VtQ3FqCw

The shade, which is about the  size of a baseball diamond, would be deployed as part a single mission. As the video above shows, the large shade would be mounted at the end of a space telescope – in this case, NASA’s upcoming Wide Field Infrared Survey Telescope (WFIRST) – and then detaches and deploys to a distance of several thousands kilometers in front of it.

Such a large shade operating at such a long distance from of its paired telescope is essential when dealing with distant stars.”Because stars are so far away the angular distance between the planet and star is quite small,” said Kasdin, “requiring a very large starshade (20 to 50 meters in diameter) flying very far from the telescope (up to 50,000 km). Nevertheless, many astronomers believe this is the best technology to detect an Earthlike planet in the near future, a belief aided by the fact that few special requirements are placed on the telescope.”

Paired with other instruments, like spectrometers, devices like the Starshade will not only allow astronomers to be able to spot planets more easily, but also obtain information about their atmospheres. By studying their chemical compositions – i.e. looking for the presence of oxygen/nitrogen, water vapor, etc. – we would be able to tell with a fair degree of certainty whether or not life exists on them.

The Starshade technology is one of the top candidates for a flagship-level mission in the next decade and a top Astro2010 priority for technology development. In addition to working with WFIRST, it is possible it will be paired with missions like the Transiting Exoplanet Survey Satellite (TESS) and the James Webb Space Telescope.

“We are hoping that a starshade capable of Earth detection will be recommended to fly with the upcoming WFIRST mission,” Kasdin added, “allowing the first image of an Earth in the next decade.”

 

Further Reading: JPL News

The post Starshade Prepares To Image New Earths appeared first on Universe Today.

100,000 Galaxies, and No Obvious Signs of Life

Beam us up, Scotty. There’s no signs of intelligent life out there. At least, no obvious signs, according to a recent survey performed by researchers at Penn State University. After reviewing data taken by the NASA Wide-field Infrared Survey Explorer (WISE) space telescope of over 100,000 galaxies, there appears to be little evidence that advanced, […]