A direct image of a planet that is just like Jupiter, only younger

In a recent study published in The letters from the astrophysicist diary, a team of astronomers used the WM Keck Observatory in Maunakea, Hawaii, to identify the exoplanet AF Lep b, which is three times the mass of Jupiter orbiting a Sun-sized star located about 87.5 light-years from Earth. What makes this discovery unique is that AF Lep b is the first exoplanet discovered using a method called astrometry, which involves measuring unexpected and tiny changes in a star’s position relative to nearby stars, which could indicate that another object, an exoplanet, is causing gravitational effects. tugs on its parent star.

This is the first time this method has been used to find a giant planet orbiting a young Sun analogue, said Dr. Brendan Bowler, who is an assistant professor of astronomy at the University of Texas at Austin ( UT Austin), and a co-author of the study. This opens the door to using this approach as a new tool for exoplanet discovery.

Additionally, the team used the direct imaging method to conduct follow-up observations and confirm initial results. This method involves slowly dimming the glare of the stars to reveal the exoplanets orbiting it, much like you would dim artificial light in an attempt to see hidden objects in a dark, surrounding environment.

Remove all ads on Universe Today

Join our Patreon for just $3!

Get the ad-free experience for life

When we processed the observations using the real-time Keck II telescope to carefully remove the star’s glare, the planet immediately popped up and became more and more apparent the longer we observed, said Kyle Franson, who is a student in the Department of Astronomy at UT Austin and lead author of the study.

Direct images of the exoplanet, AF Lep b (white dot around 10 o’clock), orbiting its host star (center) taken in December 2021 and February 2023. using the 10-meter telescope at WM Keck Observatory in Hawaii. (Credit: Kyle Franson, University of Texas at Austin/WM Keck Observatory)

Using this combined method of astrometry and direct imaging helped the team not only confirm the existence of AF Lep b, but also determine its mass to be about three times that of Jupiter, its distance from its parent star at about 8.4 astronomical units (AU), and its orbital eccentricity, which is the shape of a planet’s orbit, at about 0.24, measured from 0 to 1 where 0 is perfectly circular and 1 is a parabola. For context, Jupiter is 5.2 AU from our Sun and its eccentricity is 0.05 while Earth is 1 AU from our Sun and its eccentricity is 0.02.

Most exoplanets have been discovered using the so-called transit method, which is when an exoplanet passes in front of its parent star, thereby dimming its starlight. This method not only confirms the existence of an exoplanet, but can also be used to determine the mass of the exoplanet.

Example of the transit method used to find an exoplanet. (Credit: NASA)

The second most common method is the radial velocity (RV) method, which is when changes in the velocity of a star as it moves towards and away from Earth are measured as the exoplanet orbits it. This method varies from astrometry is that RV measures the velocity of a star while astrometry measures a change in the position of stars. Both of these methods are referred to as indirect methods since astronomers do not observe the exoplanet directly, only how it affects its parent star during its orbit.

Moving forward, Dr. Bowler said the team will continue to observe and study AF Lep b.

This will be an excellent target to further characterize with the James Webb Space Telescope and the next generation of large ground-based telescopes such as the Giant Magellan Telescope and Thirty Meter Telescope, Dr Bowler said. We are already planning more sensitive follow-up efforts at longer wavelengths to study the physical properties and atmospheric chemistry of this planet.

What new exoplanet discoveries will astronomers make using astrometry in the next few years and decades? Only time will tell, and that’s why we do science!

As always, keep doing the science and keep looking up!

#direct #image #planet #Jupiter #younger
Image Source : www.universetoday.com

Leave a Comment