There\u2019s so little we know about circumbinary planets \u2013 planets that orbit two stars instead of one \u2013 that they can feel like the stuff of fantasy.<\/p>\n
And for good reason: to date, we\u2019ve only confirmed the existence of 18 circumbinary planets, compared to the more than 6000 planets we know about in single star systems.<\/p>\n
Even the most widely-known circumbinary planet is, quite literally, fiction: the desert planet Tatooine from Star Wars, aka the birthplace of Anakin Skywalker.<\/p>\n
But a study led by UNSW has now detected 27 potential circumbinary planets in one sweep, using a new planet-finding method that broadens the typical type of planets we can find.<\/p>\n
The findings are published in the\u00a0Monthly Notices of the Royal Astronomical Society.<\/p>\n
\u201cMost of our current knowledge on planets is biased, based on how we\u2019ve looked for them,\u201d says Ms\u00a0Margo Thornton, lead author of the study, astronomer and PhD candidate at UNSW. \u201cWe\u2019ve mostly found the easiest ones to detect.<\/p>\n
\u201cThis new method could help us uncover a large population of hidden planets, especially those that don\u2019t line up perfectly from our line of sight. It could help reveal what the true population of planets in our universe might look like.\u201d<\/p>\n
The planet-finding method, called apsidal precession, has been used to characterise binary stars before, but not in a large-scale search for planets.<\/p>\n
It involves monitoring how the binary stars\u2019 orbit of one other \u2013 made visible by their stellar eclipses \u2013 change over long periods of time.<\/p>\n
If there\u2019s a variation in their (normally predictable) eclipse schedule that can\u2019t be explained by general relativity or stellar interactions, it means a third body could be influencing the stars\u2019 orbits \u2013 and that body could be a planet.<\/p>\n
The findings were made using data from\u00a0NASA\u2019s Transiting Exoplanet Survey Satellite (TESS), a space telescope launched in 2018 with the mission to search for exoplanets.<\/p>\n
\u201cI\u2019m excited about the potential for how many planets we could find with this method,\u201d says Scientia A\/Prof.\u00a0Ben Montet, astronomer and senior author on the study. \u201cI wasn\u2019t expecting to find 27 already at this point from the pilot study.<\/p>\n
\u201cNow we get to start the really fun project of figuring out which ones are real planets.\u201d
\u00a0<\/p>\n
A new way to find planets<\/p>\n
Almost all planets have been discovered by the \u2018transit\u2019 method, which is when a planet crosses in front of its star, creating a mini-eclipse.<\/p>\n
This eclipse causes a dip in the starlight signal sent to Earth, suggesting there might be a planet orbiting there.<\/p>\n
But the transit method restricts us to\u00a0only\u00a0discovering planets that cross between Earth and their star. If a planet orbits its star (or stars, in this instance) at an irregular orbit, or an orbit that isn\u2019t in our direct line of sight, it can slip under our radar.<\/p>\n
\u201cWe\u2019re missing a huge part of the architecture for these systems,\u201d says A\/Prof. Montet.<\/p>\n
The new method helps astronomers detect planets like these that we might have otherwise missed \u2013 helping to build our knowledge of what type of environments can support planet development.<\/p>\n
\u201cWith this method so far, we have 27 strong planet candidates in environments completely unlike our own solar system,\u201d says Ms Thornton, who made these findings just one year into her PhD.<\/p>\n
\u201cBy learning more about different types of planets, we can better understand how planets form and evolve, especially in these complex environments with two stars.\u201d<\/p>\n
The planets are called \u2018candidates\u2019 for now as the team need to confirm, or deny, their planet status using an additional observation method.<\/p>\n
Ms Thornton has started work on this process and hopes to have a follow-up paper ready within the next year.
\u00a0<\/p>\n
Our circumbinary neighbours<\/p>\n
The planet candidates range from objects that could be as small as the mass of Neptune to 10x as large as the mass of Jupiter.<\/p>\n
The closest is about 650 light years away from Earth, and the furthest about 18,000 away. To put this in perspective, one light year is 9.4 trillion kilometres.<\/p>\n
\u201cThe candidates are scattered across both our southern and northern skies,\u201d says A\/Prof. Montet.<\/p>\n
\u201cThis means that any time of the year, no matter when you\u2019re looking, at least one of these star systems is out there visible for you to look towards \u2013 as long as you have a telescope.\u201d<\/p>\n
Even though the candidates stretch across immense distances, they\u2019re still relatively close to our \u2018neighbourhood\u2019 in the Milky Way \u2013 although our list of circumbinary planet neighboursmay soon be growing.<\/p>\n
\u201cWe found 27 planet candidates out of 1590 binary star systems, which is an almost 2% rate of binary systems that could potentially host planets,\u201d says A\/Prof. Montet.<\/p>\n
\u201cThat implies there could potentially be thousands, or tens of thousands, of possible planets to be found with data from the Vera C. Rubin Observatory\u2019s new 10-year sky survey, the Legacy Survey of Space and Time.<\/p>\n
\u201cSo it\u2019s a really exciting first step \u2013 and it also shows that there\u2019s going to be a lot of work to do over the next few years.\u201d<\/p>\n
Learning about other worlds<\/p>\n
Most of the planets we know about in the universe are in single star systems, like our solar system.<\/p>\n
But cosmically speaking, systems like ours are in the minority: more than half of the stars in the universe are in binary or multiple star systems.<\/p>\n
\u201cWe\u2019ve painted half a picture, and the other half of the canvas is completely blank,\u201d says A\/Prof. Montet.<\/p>\n
Astronomers still have a lot of questions about planet formation in these systems \u2013 and this new planet-hunting method could help fill some of those knowledge gaps.<\/p>\n
\u201cWe can start asking questions like how common these planets are overall and if they could be habitable,\u201d says A\/Prof. Montet.<\/p>\n
\u201cIf circumbinary planets do turn out to be habitable, that means life could be anywhere. Life could be everywhere. The sheer numbers are really exciting.\u201d<\/p>\n
Ms Thornton says the search for other planets can help us learn more about our own place in the universe.<\/p>\n
\u201cUnderstanding the diversity of other worlds out there is the first step in understanding if anyone else is out there. If we are alone or not,\u201d she says.<\/p>\n
\u201cThat\u2019s what a lot of this comes back to. We just want to understand where we came from, what our place looks like in the universe, and what else exists out there.\u201d<\/p>\n
From star gazer to space explorer<\/p>\n
Ms Thornton spent a big part of her childhood on family camping trips, gazing up at the night sky.<\/p>\n
She looks back on these moments as integral to her future in astronomy.<\/p>\n
\u201cI was always out under the stars and just always had questions that my parents couldn\u2019t answer,\u201d says Ms Thornton. \u201cSo, I wanted to be able to answer them.\u201d<\/p>\n
Now, many years and answered questions later, astronomy became a passion that she could pursue as a career.<\/p>\n
\u201cMy supervisor Ben often talks about this moment in astronomy where you\u2019re the only person in the world who\u2019s seen evidence of something exciting,\u201d says Ms Thornton.<\/p>\n
\u201cWhen the first system I looked at had a clear signal that these stars were precessing, and we were able to rule out all the other causes of it, we were left with these plots and numbers that suggested we might have just found a planet.<\/p>\n
\u201cFor a little while, we were the only people on Earth who knew about it. It was a very exciting feeling \u2013 and it\u2019s a great part of working in astronomy.\u201d<\/p>\n
Answering new galactic questions<\/p>\n
Over the next few months, Ms Thornton will be studying the spectra of these binary stars \u2013 that is, the light that makes up these stars \u2013 using the\u00a0Anglo Australian telescope\u00a0in Coonabarabran. The telescope has a remote observing room accessible from UNSW Sydney\u2019s campus.<\/p>\n
The team will also be collaborating with researchers in the US, UK and China later in the year to learn more about the candidates visible from the Northern Hemisphere.<\/p>\n
Studying the spectra can help the team rule out whether the bodies they detected could be higher mass objects, like stars, brown dwarfs, white dwarfs or even black holes.<\/p>\n
If nothing else can explain the objects, they could be confirmed as planets.<\/p>\n
In the meantime, the team are also planning on applying the same planet-searching method to larger samples, and running simulations to better understand how the planet candidates formed and how they might evolve over time.<\/p>\n
\u201cI was surprised by how effective the method was and how small of a signal we could pick up on using the TESS data,\u201d says Ms Thornton. \u201cThere\u2019s good promise this method could potentially help us find objects as small as Earth.<\/p>\n
\u201cI\u2019m excited for what\u2019s to come next with this project. The universe is a lot more complex than we can directly see, and there could be a lot more of these real-life Tatooines out there.\u201d<\/p>\n","protected":false},"excerpt":{"rendered":"There\u2019s so little we know about circumbinary planets \u2013 planets that orbit two stars instead of one \u2013…\n","protected":false},"author":2,"featured_media":441139,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[7],"tags":[61,60,82],"class_list":["post-441138","post","type-post","status-publish","format-standard","has-post-thumbnail","category-science","tag-ie","tag-ireland","tag-science"],"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts\/441138","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/comments?post=441138"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts\/441138\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/media\/441139"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/media?parent=441138"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/categories?post=441138"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/tags?post=441138"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}