PDS 70

for PDS 70 (aka V1032 Centauri), plotted from TESS data The "PDS" in this star's name stands for Pico dos Dias Survey, a survey that looked for pre-main-sequence stars based on the star's infrared colors measured by the IRAS satellite. PDS 70 was identified as a T Tauri variable star in 1992, from these infrared colors. PDS 70's brightness varies quasi-periodically with an amplitude of a few hundredths of a magnitude in visible light. Measurements of the star's period in the astronomical literature are inconsistent, ranging from 3.007 days to 5.1 or 5.6 days. ==Protoplanetary disk==

The protoplanetary disk around PDS 70 was first hypothesized in 1992 and fully imaged in 2006 with phase-mask coronagraph on the VLT. The disk has a radius of approximately . In 2012 a large gap (~) in the disk was discovered, which was thought to be caused by planetary formation. The gap was later found to have multiple regions: large dust grains were absent out to 80 au, while small dust grains were only absent out to the previously-observed . There is an asymmetry in the overall shape of the gap; these factors indicate that there are likely multiple planets affecting the shape of the gap and the dust distribution. The James Webb Space Telescope has been used to detect water vapor in the inner part of the disk, where terrestrial planets may be forming. ==Planetary system==

In results published in 2018, a planet in the disk, named PDS 70 b, was imaged with SPHERE planet imager at the Very Large Telescope (VLT). A second planet, designated PDS 70 c, was discovered in 2019 using the VLT's MUSE integral field spectrograph. however, in 2020 evidence was presented that the current data favor a model with a single component of the planet. A 2021 study with newer methods and data suggested a lower accretion rate of per year. It is not clear how to reconcile these results with each other and with existing planetary accretion models; future research in accretion mechanisms and Hα emissions production should offer clarity. In July 2019, astronomers using the Atacama Large Millimeter Array (ALMA) reported the first-ever detection of a moon-forming circumplanetary disk. The disk was detected around PDS 70 c, with a potential disk observed around PDS 70 b. In 2025 two studies found variable accretion from the variable H-alpha emission line for both planet b and c. One work used Magellan/MagAO-X and the other used Hubble. Planet b did show a general fading trend, with a decrease in brightness by a factor of 4.6. Planet c did increase in brightness by a factor of 2.3 between 2023 and 2024. The MagAO-X observations also suggest in reasonably good agreement with a predicted scattered light model of a CPD that both planets are surrounded by a compact disk with a radius of about 3 astronomical units. Possible planet d VLT/SPHERE observations showed a third object 0.12 arcseconds from the star. Its spectrum is very blue, possibly due to star light reflected in dust. It could be a feature of the inner disk. The possibility does still exist that this object is a planetary mass object enshrouded by a dust envelope. For this second scenario the mass of the planet would be on the order of a few tens . JWST NIRCam observations also detected this object. It is located at around 13.5 AU and if it is a planet, it would be in a 1:2:4 mean-motion resonance with the other protoplanets. In 2025 a team combined VLT/SPHERE, VLT/NaCo, VLT/SINFONI and JWST/NIRcam observations and detected Keplerian motion of the candidate. The planet candidate is detected over nine epochs ranging nine years of observations. The orbit could be in resonance with the other planets. The spectrum in the infrared is mostly consistent with the star PDS 70, but beyond 2.3 μm an infrared excess was detected. This excess could be produced by the thermal emission of the protoplanet, by circumplanetary dust, variability or contamination. The source may not be a point-like source. The source is therefore interpreted as an outer spiral wake from protoplanet d with a dusty envelope. A feature of the inner disk is an alternative explanation of candidate d. Planet-disk simulations suggest PDS 70 "d"'s 1:2:4 mean-motion resonance locking with b and c will allow the system to remain stable in the current configuration for at least a billion years, long after the disk is fully dissipated. Another candidate, called "CC3" is consistent with a planet at 5.6 AU, but could also be a PSF artifact. It could also be a clump and the same phenomenon as planet "d" from JWST and "CC1" from Hubble, because all three candidates have the a similar position angle. Possible co-orbital body In July 2023, the likely detection of a cloud of debris co-orbital with the planet PDS 70 b was announced. This debris is thought to have a mass 0.03-2 times that of the Moon, and could be evidence of a Trojan planet or one in the process of forming. ==Gallery==

File:PDS 70 closeup - eso2111a.jpg|ALMA image of a resolved circumplanetary disk around exoplanet PDS 70c File:Exoplanets PDS 70 b and c (2019-26-4502).tif|Hubble image of PDS 70. This is only the second multi-planet system to be directly imaged. File:Water in Protoplanetary Disk of PDS 70 (MIRI Emission Spectrum) (2023-130).jpg|James Webb Space Telescope spectrum of PDS 70, detecting water in the terrestrial region of the protoplanetary disk ==See also==