![\"\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2021\/05\/PDS_70b-c.jpeg\")
<\/p>\nIn 2018, the exo-planet PDS 70b was observed using the Very Large Array. It\u2019s discovery instantly placed it at the top of observation requests and telescope time for one quite profound reason: the exoplanet was still forming.<\/p>\n
For the first time, a still-accreting planet had been discovered, providing astrophysicists a unique opportunity to study how planets form with real-time observations. But one pesky problem existed: PDS 70b was far too close to its parent star for the usual exoplanet observational techniques to allow researchers to measure the planet\u2019s growth rate.<\/p>\n
Now, for the first time ever using UV-band observations, a group of astrophysicists working with the Hubble Space Telescope\u2019s Wide Field Camera 3 have produced the first measurement of PDS 70b\u2019s current growth rate.<\/p>\n<\/p>\n
The exoplanet in question orbits the star PDS 70 \u2014 a young, 10 million year old, K5 spectral type, low-mass T Tauri star located approximately 370 light-years from our solar system in the constellation Centaurus.<\/p>\n
A 140 AU-wide (1 Astronomical Unit , or AU, is equal to the average distance of Earth from the Sun: approximately 149 million kilometers) accretion disk around the star was confirmed in 2006, with an approximately 65 AU gap in that disk found in 2012.<\/p>\n
The gap instantly intensified interest in PDS 70, as large gaps in young star systems\u2019 accretion disks are usually an indication of forming planets according to models of stellar system development.<\/p>\n
<\/p>\n
PDS 70b seen in this image from the Very Large Telescope. The planet stands out as a bright point to the right of the center of the image. (Credit: ESO, VLT, Andr\u00e9 B. M\u00fcller)<\/p>\n
In 2018, exoplanet PDS 70b was found in a 119.2 year orbit located approximately 20 AU from its parent star using the Very Large Telescope in Chile. The massive Jupiter-like planet, itself more than five times Jupiter\u2019s mass, was too close to its parent star to be observed in the ways necessary to discern its current accretion (or growth) rate.<\/p>\n
Space tourism guides (adsbygoogle = window.adsbygoogle || []).push({});<\/p>\n \u201cTo study this specific planet, it needs UV information,\u201d said Dr. Yifan Zhou, Postdoctoral Fellow, McDonald Observatory, University of Austin and lead author on the new study on PSD 70b\u2019s accretion measurement, in an interview with NASASpaceflight.<\/p>\n \u201cHubble is basically the only telescope that can do this work\u201d due to the detail and precision of the observations,\u201d noted Dr. Zhou.<\/p>\n Using the orbital Hubble Space Telescope to observe the PDS 70 system gave Zhou et al. their best chance of seeing the exoplanet in the UV wavelength. However, \u201cthe non-ideal part of Hubble compared to ground-based telescopes [is that] Hubble has a very small mirror. It\u2019s only 2.4 meters.\u201d<\/p>\n The smaller the mirror, the less sharp the image. To account for this, the team employed multiple techniques \u2014 some for the first time with UV observations \u2014 to pull the exoplanet from the data while ensuring they were not detecting a false positive.<\/p>\n \u201cOne very important concept here, the application we use in this observation is called angular differential imaging. You take the image with different position angles, and your PSF, the point spread function structure is rotating with the telescope but your planet is staying in the same position,\u201d related Dr. Zhou.<\/p>\n<\/p>\n