NASA’s Roman Mission Will Probe Galaxy’s Core for Hot Jupiters, Brown Dwarfs

Illustration depicting a brown dwarf, which range from about 4,000 to 25,000 times Earth’s mass. They’re too heavy to be characterized as planets, but not quite massive enough to undergo nuclear fusion in their cores like stars.

Watch this video on the NASA.gov Video YouTube channel.

Animated gif of the above.

Animation depicting the xallarap effect. As a planet moves around its host star, it exerts a tiny gravitational tug that shifts the star’s position a bit. This can pull the distant star closer and farther from a perfect alignment. Since the nearer star acts as a natural lens, it’s like the distant star’s light will be pulled slightly in and out of focus by the orbiting planet. By picking out little shudders in the starlight, astronomers will be able to infer the presence of planets.

Xallarap is parallax spelled backward. Parallax relies on motion of the observer – Earth moving around the Sun – to produce a change in the alignment between the distant source star, the closer lens star and the observer. Xallarap works the opposite way, modifying the alignment due to the motion of the source.

While microlensing is generally best suited to finding worlds farther from their star than Venus is from the Sun, the xallarap effect works best with very massive planets in small orbits, since they make their host star move the most. Revealing more distant planets will also allow us to probe a different population of worlds.

Watch this video on the NASA.gov Video YouTube channel.

Animated gif of the above