Till now, astronomers have discovered all different identified exoplanets and exoplanet candidates in the Milky Means galaxy, virtually all lower than about 3,000 light-years from Earth.
Indicators of a planet transiting a star exterior of the Milky Means galaxy could have been detected for the first time. This intriguing end result, utilizing NASA’s Chandra X-ray Observatory, opens up a brand new window to seek for exoplanets at better distances than ever earlier than.
The potential exoplanet candidate is positioned in the spiral galaxy Messier 51 (M51), additionally known as the Whirlpool Galaxy due to its distinctive profile.
Exoplanets are outlined as planets exterior of our Photo voltaic System. Till now, astronomers have discovered all different identified exoplanets and exoplanet candidates in the Milky Means galaxy, virtually all of them lower than about 3,000 light-years from Earth. An exoplanet in M51 can be about 28 million light-years away, which means it will be 1000’s of instances farther away than these in the Milky Means.
“We are attempting to open up an entire new enviornment for locating different worlds by trying to find planet candidates at X-ray wavelengths, a method that makes it potential to find them in different galaxies,” stated Rosanne Di Stefano of the Heart for Astrophysics | Harvard & Smithsonian (CfA) in Cambridge, Massachusetts, who led the research, which was revealed on October 25, 2021, in Nature Astronomy.
This new result’s primarily based on transits, occasions wherein the passage of a planet in entrance of a star blocks a few of the star’s gentle and produces a attribute dip. Astronomers utilizing each ground-based and space-based telescopes – like these on NASA’s Kepler and TESS missions – have looked for dips in optical gentle, electromagnetic radiation people can see, enabling the discovery of 1000’s of planets.
Di Stefano and colleagues have as a substitute looked for dips in the brightness of X-rays acquired from X-ray brilliant binaries. These luminous techniques usually include a neutron star or black gap pulling in fuel from a carefully orbiting companion star. The fabric close to the neutron star or black gap turns into superheated and glows in X-rays.
As a result of the area producing brilliant X-rays is small, a planet passing in entrance of it may block most or all of the X-rays, making the transit simpler to identify as a result of the X-rays can utterly disappear. This might permit exoplanets to be detected at a lot better distances than present optical gentle transit research, which should have the ability to detect tiny decreases in gentle as a result of the planet solely blocks a tiny fraction of the star.
The workforce used this technique to detect the exoplanet candidate in a binary system known as M51-ULS-1, positioned in M51. This binary system incorporates a black gap or neutron star orbiting a companion star with a mass about 20 instances that of the Solar. The X-ray transit they discovered utilizing Chandra information lasted about three hours, throughout which the X-ray emission decreased to zero. Primarily based on this and different data, the researchers estimate the exoplanet candidate in M51-ULS-1 can be roughly the measurement of Saturn, and orbit the neutron star or black gap at about twice the distance of Saturn from the Solar.
Whereas this can be a tantalizing research, extra information can be wanted to confirm the interpretation as an extragalactic exoplanet. One problem is that the planet candidate’s giant orbit means it will not cross in entrance of its binary accomplice once more for about 70 years, thwarting any makes an attempt for a confirming remark for many years.
“Sadly to verify that we’re seeing a planet we’d probably have to attend many years to see one other transit,” stated co-author Nia Imara of the College of California at Santa Cruz. “And due to the uncertainties about how lengthy it takes to orbit, we wouldn’t know precisely when to look.”
Can the dimming have been brought on by a cloud of fuel and mud passing in entrance of the X-ray supply? The researchers think about this to be an unlikely rationalization, as the traits of the occasion noticed in M51-ULS-1 should not in line with the passage of such a cloud. The mannequin of a planet candidate is, nonetheless, in line with the information.
“We all know we’re making an thrilling and daring declare so we count on that different astronomers will have a look at it very fastidiously,” stated co-author Julia Berndtsson of Princeton College in New Jersey. “We expect now we have a robust argument, and this course of is how science works.”
This artist’s animation depicts the potential detection of a planet candidate in a double system in the M51 (“Whirlpool”) galaxy. The view begins exterior of the galaxy after which travels into the star cluster containing the binary system known as M51-ULS. This incorporates both a neutron star or a black gap in orbit with a star about 20 to 30 instances the mass of the Solar (giant blue star). The neutron star or black gap is pulling materials from its companion star, making a disk of fabric that glows in X-rays (purple, orange, and yellow). Credit score: NASA/CXC/A. Hobart
If a planet exists on this system, it probably had a tumultuous historical past and violent previous. An exoplanet in the system would have needed to survive a supernova explosion that created the neutron star or black gap. The long run can also be harmful. In some unspecified time in the future the companion star may additionally explode as a supernova and blast the planet as soon as once more with extraordinarily excessive ranges of radiation.
Di Stefano and her colleagues seemed for X-ray transits in three galaxies past the Milky Means galaxy, utilizing each Chandra and the European House Company’s XMM-Newton. Their search coated 55 techniques in M51, 64 techniques in Messier 101 (the “Pinwheel” galaxy), and 119 techniques in Messier 104 (the “Sombrero” galaxy), leading to the single exoplanet candidate described right here.
This artist’s animation depicts the potential detection of a planet candidate in a double system in the M51 (“Whirlpool”) galaxy known as M51-ULS. This technique incorporates both a neutron star or a black gap in orbit with a star about 20 to 30 instances the mass of the Solar (giant blue star). The neutron star or black gap is pulling materials from its companion star, making a disk of fabric that glows in X-rays (purple, orange, and yellow). Credit score: NASA/CXC/A. Hobart
The authors will search the archives of each Chandra and XMM-Newton for extra exoplanet candidates in different galaxies. Substantial Chandra datasets can be found for no less than 20 galaxies, together with some like M31 and M33 which can be a lot nearer than M51, permitting shorter transits to be detectable. One other attention-grabbing line of analysis is to seek for X-ray transits in Milky Means X-ray sources to find new close by planets in uncommon environments.
For extra on this discovery, learn First Evidence for a Possible Planet Outside of the Milky Way Galaxy.
Reference: “A potential planet candidate in an exterior galaxy detected via X-ray transit” by Rosanne Di Stefano, Julia Berndtsson, Ryan Urquhart, Roberto Soria, Vinay L. Kashyap, Theron W. Carmichael and Nia Imara, 25 October 2021, Nature Astronomy.
The opposite authors of this Nature Astronomy paper are Ryan Urquhart (Michigan State College), Roberto Soria (College of the Chinese language Science Academy), Vinay Kashap (CfA), and Theron Carmichael (CfA). NASA’s Marshall House Flight Heart manages the Chandra program. The Smithsonian Astrophysical Observatory’s Chandra X-ray Heart controls science from Cambridge Massachusetts and flight operations from Burlington, Massachusetts.