The "PDS" in this star's name stands forPico dos Dias Survey, a survey that looked forpre-main-sequence stars based on the star's infraredcolors measured by theIRAS satellite.[10]PDS 70 was identified as a T Tauri variable star in 1992, from these infrared colors.[11] PDS 70's brightness varies quasi-periodically with an amplitude of a few hundredths of amagnitude in visible light.[12] Measurements of the star's period in the astronomical literature are inconsistent, ranging from 3.007 days to 5.1 or 5.6 days.[13][14]
The protoplanetary disk of PDS 70 with new planet PDS 70b (right)
The protoplanetary disk around PDS 70 was first hypothesized in 1992[15] and fully imaged in 2006 with phase-mask coronagraph on the VLT.[2] The disk has a radius of approximately140 au. In 2012 a large gap (~65 au) in the disk was discovered, which was thought to be caused by planetary formation.[6][16]
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-observed65 au. 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.[17]
In results published in 2018, a planet in the disk, named PDS 70 b, was imaged with SPHERE planet imager at theVery Large Telescope (VLT).[3][8] With a mass estimated to be a few times greater thanJupiter,[20] the planet is thought to have a temperature of around 1,200 K (930 °C; 1,700 °F)[23] and an atmosphere with clouds;[8] its orbit has an approximateradius of 20.8 AU (3.11 billion kilometres),[20] taking around 120 years for a revolution.[21]
The emission spectrum of the planet PDS 70 b is gray and featureless, and no molecular species were detected by 2021.[24]
A second planet, designated PDS 70 c, was discovered in 2019 using the VLT's MUSEintegral field spectrograph.[25] The planet orbits its host star at a distance of 34.3 AU (5.13 billion kilometres), farther away than PDS 70 b.[20] PDS 70 c is in a near 1:2orbital resonance with PDS 70 b, meaning that PDS 70 c completes nearly one revolution once every time PDS 70 b completes nearly two.[25]
Modelling predicts that PDS 70 b has acquired its owncircumplanetary disk (CPD).[7][26] The CPD was at first observationally supported in 2019,[27] however, in 2020 evidence was presented that the current data favor a model with a single component of the planet.[28] The accretion rate was measured to be at least5 • 10−7 Jupiter masses per year.[29] A 2021 study with newer methods and data suggested a lower accretion rate of(1.4±0.2)×10−8MJ per year.[30] 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.[31]
In July 2019, astronomers using theAtacama Large Millimeter Array (ALMA) reported the first-ever detection of a moon-formingcircumplanetary disk. The disk was detected around PDS 70 c, with a potential disk observed around PDS 70 b.[32][33][34] The two planets and the superposition of PDS 70 c and the protoplanetary disk was confirmed byCaltech-led researchers using theW. M. Keck Observatory inMauna Kea, whose research was published in May 2020.[35] An image of the circumplanetary disk around PDS 70 c separated from the protoplanetary disk was finally confirming thecircumplanetary disk and was published in November 2021.[36]
In 2025 two studies found variable accretion from the variableH-alpha emission line for both planet b and c. One work usedMagellan/MagAO-X and the other usedHubble. 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 3astronomical units.[37][38]
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 tensM🜨.[21] JWSTNIRCam observations also detected this object. It is located at around 13.5 AU and if it is a planet, it would be in a 1:2:4mean-motion resonance with the other protoplanets.[39] In 2025 a team combinedVLT/SPHERE, VLT/NaCo, VLT/SINFONI and JWST/NIRcam observations and detectedKeplerian 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 aninfrared excess was detected. This excess could be produced by the thermal emission of the protoplanet, bycircumplanetary 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.[22]
Another candidate, called "CC3" is consistent with a planet at 5.6 AU, but could also be aPSF 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 similarposition angle.[37]
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 timesthat of the Moon, and could be evidence of aTrojan planet or one in the process of forming.[40][41]
^Gregorio-Hetem, J.; Lepine, J. R. D.; Quast, G. R.; Torres, C. A. O.; de La Reza, R. (1992). "A search for T Tauri stars based on the IRAS point source catalog".The Astronomical Journal.103: 549.Bibcode:1992AJ....103..549G.doi:10.1086/116082.
^Cugno, G.; Patapis, P.; Stolker, T.; Quanz, S. P.; Boehle, A.; Hoeijmakers, H. J.; Marleau, G.-D.; Mollière, P.; Nasedkin, E.; Snellen, I. A. G. (2021), "Molecular mapping of the PDS70 system",Astronomy & Astrophysics,653: A12,arXiv:2106.03615,doi:10.1051/0004-6361/202140632,S2CID235358211
^Zhou, Yifan; Bowler, Brendan P.; Wagner, Kevin R.; Schneider, Glenn; Apai, Dániel; Kraus, Adam L.; Close, Laird M.; Herczeg, Gregory J.; Fang, Min (2021), "Hubble Space Telescope UV and Hα Measurements of the Accretion Excess Emission from the Young Giant Planet PDS 70 B",The Astronomical Journal,161 (5): 244,arXiv:2104.13934,Bibcode:2021AJ....161..244Z,doi:10.3847/1538-3881/abeb7a,S2CID233443901
^Gebhardt, Chris; Warren, Haygen (2021-05-13)."With Hubble, astronomers use UV light for first time to measure a still-forming planet's growth rate".NSF (NASASpaceflight)....and that's lower than super-Jupiter gas giant planet formation models predict. Zhou et al. are quick to caution that their calculations are a snapshot in time. Additional observation, multi-decade, multi-century observations will reveal if accretion rates fluctuate greatly over time as planets go through growth spurts, so to speak, followed by periods of less active formation or if "Hα production in planetary accretion shocks is more efficient than [previous] models predicted, or [if] we underestimated the accretion luminosity/rate," noted Zhou et al. in their paper published in April 2021 issue of The Astronomical Journal. The team further noted, "By combining our observations with planetary accretion shock models that predict both UV and Hα flux, we can improve the accretion rate measurement and advance our understanding of the accretion mechanisms of gas giant planets."
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