Jupiter-sized exoplanet detected

David et al. 2019 recently reported the detection of exoplanet V1298 Tau b. The first part of the name (i.e., V1298 Tau) represents the 1298th variable star found within the Taurus constellation boundaries. Then, per the exoplanet naming convention, the "b" denotes the first planet found in that solar system. This planet is about the size of Jupiter and is located relatively close to its star, making it a "warm Jupiter", similar to the well-known "hot Jupiters". Many "hot Jupiters" have been discovered using the radial velocity method, where the detection is made possible by the gravitational interaction of the star and its nearby, relatively large planet. However, V1298 Tau b is unique in that its orbit around its star is aligned with the line of sight from Earth, making it detectable via the transit method (see Figure 1).

Figure 1. Exoplanet orbit orientations. Credit: Las Cumbres Observatory

Using this technique, the exoplanet's existence can be deduced when it crosses (i.e., transits) between the star and the observer, creating a brief dip in the brightness of the star from the perspective of the observer. Although these dips are quite small, they are measurable and provide lots of information about the planet. The light curve for V1298 Tau was created using observations taken with the NIRC2 (near-infrared camera) instrument on the Keck Telescope and can be seen in Figure 2. The astronomers also concluded that the star is relatively young at about 23 million years old. This suggests that the planet V1298 Tau b formed in place (i.e., near its sun) as opposed to forming in the outer solar system and moving inwards via the ["planet migration"] hypothesis. V1298 Tau b's unique characteristics make it a valuable target for follow up studies to discover more about "warm Jupiters".

Figure 2. Light curve for V1298 Tau b showing the characteristic dip in relative brightness during the planetary transit. The blue-filled circles represent observations that were included in the final analysis while the open circles were excluded due to instrumentation issues. Credit: David et al. 2019

References

David, T. J. et al. 2019, https://arxiv.org/pdf/1902.09670.pdf