Rare Aliens World View Uncovered in Revolutionary Planet-Hunting Technology

 

A timelapse of images from the Subaru Telescope showing the motion of HIP-99770b around its star. (T. Currie/Subaru Telescope/UTSA)

The discovery of a brand-new extraterrestrial world is due to the velocity of a star as it travels across the cosmos.

 

Astronomers have discovered a kink in the path of a star called HIP-99770, suggesting the presence of a nearby planet, using data from the Gaia satellite that is mapping the Milky Way.

A rare, direct image of the purported exoplanet, which was later given the label HIP-99770b, was then discovered through following observations. It's the first time that direct imaging and astrometry, which tracks a star's motion, have been combined to find an orbiting planet.

 

These initiatives represent a fresh and successful approach to looking for planets outside the Solar System, helping us to better comprehend the variety of planetary systems out there as well as seek for potential new homeworlds for life.

Astronomer Thayne Currie of the Subaru Telescope and the University of Texas at San Antonio says that by using both direct imaging and astrometry, it is possible to monitor an exoplanet's orbit, measure its atmosphere, and weigh it all at once.

This innovative method of planet discovery anticipates how we will one day recognise and describe an Earth-twin planet orbiting a nearby star.

It's not easy to find exoplanets. They are extremely distant, tiny, and dark in comparison to the stars they circle. This translates to the fact that we never actually see them. The blazing of their star overpowers any light they may reflect or emit. The majority of the more than 5,300 verified exoplanets discovered to date, however, have only been indirectly discovered.

 

There are two basic approaches to achieving this, and both are more effective at locating exoplanets that are in close orbits around their stars. The first is to search for transits, which are the sporadic, small dips in sunlight caused by an exoplanet in orbit that passes in front of the star.

The second involves watching for variations in a star's light's wavelength, or Doppler shifts, as it goes around the exoplanet it shares an orbit with.

 

This is due to the fact that the exoplanet's gravity also influences the star; the two bodies dance around this centre like an Olympic hammer thrower. There are several methods for detecting this star motion.

The wiggle in a star's motion that reveals the gravitational influence of an exoplanet. (ESA)

In the Milky Way, stars orbit the galactic centre in a manner similar to how the planets in our solar system orbit the Sun; they are not stationary. The astrometric method therefore searches for deviations from a straight line of movement as the star moves through the galaxy rather than using changes in wavelengths. Exoplanets with bigger orbits around their stars, which Doppler shifts won't show, can be found using this technique.

Additionally, exoplanets with greater distances from their stars provide better prospects for direct imaging since they are far enough away to be seen through the star's glare.

 

The majority of exoplanet discoveries to date have been made via indirect planet detection techniques. Precision astrometry, one of these techniques, advised us on where to go in order to try and image planets, explains Currie. And, as we discovered, planets are much easier to view now.

 

In data gathered by the Gaia and Hipparcos spacecraft—European Space Agency missions tasked with mapping the Milky Way, including the positions and motions of the stars—the researchers searched for direct imaging prospects. They now had a 25-year star position record.

Additionally, better exoplanets are those that are farther away from their stars. Numerous stars displayed signs of a wriggling motion that would indicate the presence of a massive exoplanet. In order to directly search for these worlds, the Subaru Telescope and the Keck Observatory in Hawaii were put to use. And on one of the first stars they looked at, they caught a massive one.

One of the Subaru images of HIP-99770b. ( T. Currie/Subaru Telescope/UTSA)

HIP-99770b is an exoplanet with a radius of 1.05 times that of Jupiter, a mass between 14 and 16 times that of Jupiter, and an orbital distance of 17 astronomical units around a star twice the mass of the Sun. That is somewhat closer than Uranus' 19.8 astronomical unit-distance and more than three times Jupiter's 5 astronomical unit-distance from the Sun.

However, because the star HIP-99770 is so much brighter than our Sun, it receives roughly the same amount of radiation as Jupiter does. The team was able to directly observe the exoplanet, which allowed them to measure its characteristics. Its atmosphere has signs of both water and carbon monoxide, and it is warmer and less hazy than other exoplanets orbiting the star HR 8799 that have been directly observed before.

 

The direct photos also showed the presence of an icy debris disc like the Kuiper Belt in the Solar System orbiting the star at a distance of about 150 astronomical units. Without a doubt, more investigation will investigate the exoplanet to see what else we may learn through direct imagery.

The roughly 50 potential stars that the researchers found in the Gaia-Hipparcos data are still being observed and examined by the researchers in the meantime. Although HIP-99770b is a demonstration of their methods, they are still far from finished.

 

This is the first discovery made as part of our Keck and Subaru imaging programme, which chooses targets using astrometry. We have already made new findings, and we will announce them later this year and next," says Currie.

 

He continues, "We are now in a new era for imaging other worlds."

Reference: Sciencealert.com