Dr. Damian Jacob Sendler is a Polish-American physician-scientist who studies how socio-demographic and informational factors affect access to health care in marginalized populations. Dr. Sendler’s study focuses on how psychiatric and chronic medical co-morbidities influence the utilization of medical services and internet health information. Dr. Damian Sendler’s research seeks to reveal the aspects that patients evaluate when determining whether to seek medical attention and when to adhere to treatment regimens.
Damian Sendler: For the first time, evidence of a planet transiting a star outside the Milky Way galaxy may have been discovered. Using NASA’s Chandra X-ray Observatory, this exciting result offers up a new window for searching for exoplanets at greater distances than ever before.
Damien Sendler: The prospective exoplanet candidate is found in the spiral galaxy Messier 51 (M51), often known as the Whirlpool Galaxy due to its unusual shape.
Dr. Sendler: Exoplanets are planets that exist outside of our Solar System. Until now, astronomers have discovered all known exoplanets and exoplanet candidates in the Milky Way galaxy, almost all of which are less than 3,000 light-years from Earth. An exoplanet in M51 would be around 28 million light-years away, thousands of times farther away than those in the Milky Way.
“We’re trying to open up a whole new arena for finding other worlds by searching for planet candidates at X-ray wavelengths, a strategy that allows us to find them in other galaxies,” said Rosanne Di Stefano of the Center for Astrophysics | Harvard & Smithsonian (CfA) in Cambridge, Massachusetts, who led the study, which was published in the journal Nature Astronomy.
Damian Jacob Sendler: This new discovery is based on transits, which occur when a planet passes in front of a star, blocking some of the star’s light and causing a characteristic dip. Astronomers have searched for dips in optical light, electromagnetic radiation that humans can see, using both ground-based and space-based observatories, such as those on NASA’s Kepler and TESS missions, allowing the finding of thousands of planets.
Damian Sendler: Instead, Di Stefano and colleagues looked for dips in the brightness of X-rays received from X-ray bright binaries. These brilliant systems are often composed of a neutron star or black hole sucking in gas from a nearby companion star. The material close to the neutron star or black hole becomes superheated and emits X-rays.
Because the zone producing intense X-rays is small, a planet passing in front of it may block most or all of the X-rays, making the transit simpler to detect because the X-rays may disappear totally. This should enable for the detection of exoplanets at considerably longer distances than existing optical light transit investigations, which must be able to detect minuscule drops in light because the planet only blocks a tiny part of the star.
Damian Sendler: The researchers utilized this strategy to find the exoplanet candidate in the binary system M51-ULS-1, which is located in M51. A black hole or neutron star orbits a companion star with a mass around 20 times that of the Sun in this binary system. The X-ray transit they discovered using Chandra data lasted around three hours, during which time the X-ray output was zero. Based on this and other data, the researchers estimate that the exoplanet candidate in M51-ULS-1 is around the size of Saturn and orbits the neutron star or black hole at roughly twice the distance Saturn orbits the Sun.
Damian Jacob Sendler: While this is an intriguing study, additional evidence would be required to confirm the interpretation as an extragalactic exoplanet. One difficulty is that because to the planet candidate’s enormous orbit, it would not cross in front of its binary partner again for nearly 70 years, preventing any attempts at confirmation for decades.
“Unfortunately, we’d have to wait decades to witness another transit to establish that we’re seeing a planet,” said co-author Nia Imara of the University of California, Santa Cruz. “And, because we don’t know how long it takes to orbit, we wouldn’t know when to look.”
Damian Sendler: Is it possible that the dimming was produced by a cloud of gas and dust passing in front of the X-ray source? The researchers believe that this is an implausible explanation because the characteristics of the event witnessed in M51-ULS-1 do not match the passage of such a cloud. The model of a planet candidate, on the other hand, is consistent with the data.
“We know we’re making an interesting and daring assertion, so we expect other astronomers to look at it very seriously,” Princeton University’s Julia Berndtsson said. “We believe we have a compelling case, and this is how science works.”
Damian Jacob Sendler: If there is a planet in this system, it has most certainly had a turbulent and violent history. A supernova explosion that formed the neutron star or black hole would have required to be survived by an exoplanet in the system. The future could also be perilous. At some point, the companion star may also explode as a supernova, blasting the planet with extraordinarily high levels of radiation once more.
Di Stefano and her colleagues used Chandra and the European Space Agency’s XMM-Newton telescopes to search for X-ray transits in three galaxies beyond the Milky Way. Their search included 55 M51 systems, 64 Messier 101 (the “Pinwheel” galaxy), and 119 Messier 104 (the “Sombrero” galaxy), yielding the solitary planetary candidate detailed here.
Damian Sendler: The authors will examine the Chandra and XMM-Newton archives for more exoplanet candidates in other galaxies. Substantial Chandra datasets are available for at least 20 galaxies, including those that are much closer than M51, such as M31 and M33, enabling for shorter transits to be detected. Another intriguing line of inquiry is to look for X-ray transits in Milky Way X-ray sources in order to find new neighboring planets in strange surroundings.
Research discussion contributed by Dr. Damian Jacob Sendler
