Skip to main content

A planet is orbiting star where it should have been destroyed.

 



The discovery of an enormous planet orbiting a dying star, known as 8 Ursae Minoris b, is shaking up our understanding of how planets form and the limits of stellar destruction. Astronomers have been surprised to find the planet in a stable, nearly circular orbit around the star, as it had been expected that the red giant would have expanded beyond the planet’s orbit before shrinking to its current size. This means that any planets orbiting closely would have been engulfed and ripped apart. This discovery relied on precise measurements from NASA’s Transiting Exoplanet Survey Satellite (TESS), and suggests that planet formation and destruction processes are more complex and unpredictable than previously thought.


As stars like our Sun approach the end of their lives, they exhaust their nuclear fuel and become red giants, expanding to their maximum size. In this case, the star would have grown to 0.7 AU - three-quarters the distance from Earth to the Sun. It would have destroyed any nearby planets, however planet b, a large gaseous world, sits at 0.5 AU, making it impossible for it to have survived engulfment. Lead author Marc Hon proposed two other possibilities for planet b: that it is the survivor of a star merger, or it is a newly formed planet out of the debris from the merger. This suggests that star mergers may be more common than previously thought, and opens up an interesting new avenue for research on planetary formation and evolution.


The first scenario begins with two stars that are similar to our Sun in close orbit around each other, with a planet orbiting them both. One of the stars evolves faster than the other, going through its red giant phase and turning into a white dwarf. The other star just reaches the red giant stage before they collide, resulting in the red giant we see today. This violent merger stops the red giant from expanding further, thus sparing the orbiting planet from destruction. In the second scenario, the merger ejects an abundance of dust and gas that forms a disk around the remaining red giant. This protoplanetary disk provides the material for a new planet to form. It is almost like having a second life for a planetary system, albeit one near its end.


Astronomers are able to infer chaotic series of events from present day observations by understanding the stellar physics. Thanks to the space telescope TESS, astronomers are able to monitor jitters and quakes on distant stars. This phenomenon is known as “asteroseismology” and by studying the oscillations on 8 Ursae Minoris, the discovery team found that it reflects a late helium-burning stage rather than a star that is still expanding and burning hydrogen. This suggests that the crisis of the star has already occurred, yet the planet still somehow continues to exist. In order to understand how this is possible, astronomers continue to study the stellar physics in order to gain insight into this extraordinary phenomenon.

Comments

Popular posts from this blog

New Method Detects Small Asteroids in Main Belt, Offering Insight for Planetary Defense.

  An international team of physicists, led by MIT researchers, has developed a groundbreaking method to detect small asteroids, as small as 10 meters in diameter, within the main asteroid belt. These space rocks, ranging from the size of a bus to several stadiums wide, were previously undetectable using traditional methods. The team's discovery, detailed in a paper published in Nature, could significantly improve tracking of potential asteroid impactors, aiding planetary defense efforts. The main asteroid belt, located between Mars and Jupiter, is home to millions of asteroids, but until now, scientists could only detect objects roughly a kilometer in diameter. The new detection technique, which utilizes the "shift and stack" method, is able to identify much smaller asteroids, even those far from Earth, enabling more precise orbital tracking. This breakthrough is crucial for planetary defense, allowing scientists to spot near-Earth objects that may pose a threat in the fu...

Tropical Cyclone Sean Hits Western Australia, Breaking Rainfall Records and Causing Damage.

  On January 17, 2025, a tropical low formed over the Indian Ocean off Western Australia. By January 19, the system had intensified into Tropical Cyclone Sean, marking the second tropical cyclone of Australia’s 2024–2025 season. NASA’s Terra satellite, using the MODIS (Moderate Resolution Imaging Spectroradiometer) instrument, captured a detailed image of the storm at around 10 a.m. local time (02:00 Universal Time) on January 20, 2025. Later that same day, Cyclone Sean reached its peak strength as a Category 4 storm. Despite staying offshore and not making landfall, Cyclone Sean still brought significant impacts to the Pilbara coast. The Australian Bureau of Meteorology (BoM) reported that Karratha, a coastal city in the region, received a staggering 274.4 millimeters (10.8 inches) of rain in just 24 hours, setting a new single-day rainfall record for the city. The powerful storm caused widespread flooding, with roads submerged, homes affected, and power infrastructure damaged. Se...

NASA/ESA Hubble Space Telescope Reveals New Details of the Orion Nebula’s Star Formation.

  This NASA/ESA Hubble Space Telescope image captures the Orion Nebula (Messier 42, M42), the nearest star-forming region to Earth, located about 1,500 light-years away. A captivating new image captured by the NASA/ESA Hubble Space Telescope offers an extraordinary look into the Orion Nebula, the nearest massive star-forming region to Earth. Located just 1,500 light-years away, this nebula is visible to the naked eye below the three stars forming Orion's "belt." The region is home to hundreds of newborn stars, including two protostars featured in the image: HOPS 150 and HOPS 153. Named after the Herschel Orion Protostar Survey, conducted with ESA’s Herschel Space Observatory, the protostars HOPS 150 and HOPS 153 provide key insights into the early stages of star formation. HOPS 150, visible in the upper-right corner of the image, is a binary star system, with two young stars orbiting one another. These protostars are surrounded by small dusty disks, where material from th...