PDS 70

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PDS 70
PDS 70.jpg
The protoplanetary disk of PDS 70 with new planet PDS 70b (right)
Observation data
Epoch J2000      Equinox J2000
Constellation Centaurus
Right ascension 14h 08m 10.15451s[1]
Declination −41° 23′ 52.5766″[1]
Apparent magnitude (V) 12[2]
Characteristics
Evolutionary stage Pre-main-sequence
(T Tauri)
Spectral type K7[3]
U−B color index 0.71[4]
B−V color index 1.06[4]
Astrometry
Radial velocity (Rv)3.13[1] km/s
Proper motion (μ) RA: -29.661[1] mas/yr
Dec.: -23.823[1] mas/yr
Parallax (π)8.8159 ± 0.0405 mas[1]
Distance370 ± 2 ly
(113.4 ± 0.5 pc)
Details
Mass0.76 ± 0.02[3] M
Radius1.26 ± 0.15[3] R
Luminosity0.35 ± 0.09[3] L
Temperature3972 ± 36[3] K
Rotation~50 days[5]
Rotational velocity (v sin i)~10[5] km/s
Age5.4 ± 1[3] Myr
Other designations
V1032 Cen, 2MASS J14081015-4123525, IRAS 14050−4109
Database references
SIMBADdata

PDS 70 (V1032 Centauri) is a very young T Tauri star in the constellation Centaurus. Located approximately 370 light-years from Earth, it has a mass of 0.76 M and is approximately 5.4 million years old.[3] The star has a protoplanetary disk containing two nascent exoplanets, named PDS 70b and PDS 70c, which have been directly imaged by the European Southern Observatory's Very Large Telescope. PDS 70b was the first confirmed protoplanet to be directly imaged.[6][7][3]

Discovery and naming[edit]

A light curve for PDS 70 (aka V1032 Centauri), plotted from TESS data[8]

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.[9] PDS 70 was identified as a T Tauri variable star in 1992, from these infrared colors.[10] PDS 70's brightness varies quasi-periodically with an amplitude of a few hundredths of a magnitude in visible light.[11] Measurements of the star's period in the astronomical literature are inconsistent, ranging from 3.007 days to 5.1 or 5.6 days.[12][13]

Protoplanetary disk[edit]

ALMA image of a resolved circumplanetary disk around exoplanet PDS 70c

The protoplanetary disk around PDS 70 was first hypothesized in 1992[14] and fully imaged in 2006 with phase-mask coronagraph on the VLT.[2] The disk has a radius of approximately 140 au. In 2012 a large gap (~65 au) in the disk was discovered, which was thought to be caused by planetary formation.[5][15]

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 65 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.[16]

Planetary system[edit]

The PDS 70 planetary system[17][18]
Companion
(in order from star)
Mass Semimajor axis
(AU)
Orbital period
(days)
Eccentricity Inclination Radius
b 7.0±0.5 MJ 22.7+2.0
−0.5
45108+3580
−1790
0.17±0.06[19] 131.0+2.9
−2.6
[19]°
1.75±0.75 RJ
c 4.4±1.1 MJ 30.2+2.0
−2.4
69945+5771
−11500
0.037+0.041
−0.025
[19]
130.5+2.5
−2.4
[19]°
Protoplanetary disk ~65–140 AU ~130°

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).[3][7] With a mass estimated to be a few times greater than Jupiter, the planet was thought to have a temperature of around 1000 °C and an atmosphere with clouds; its orbit has an approximate radius of 3.22 billion kilometres (21.5 au), taking around 120 years for a revolution. Modelling predicts that the planet has acquired its own accretion disk.[6][20] The accretion disk was observationally confirmed in 2019,[21] and accretion rate was measured to be at least 5*10−7 Jupiter masses per year.[22] A 2021 study with newer methods and data suggested a lower accretion rate of 1.4±0.2*10−8 MJ/year.[23] 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.[24] The optically thick accretion disk radius is 3.0±0.2 RJ, significantly larger than planet itself. Its bolometric temperature is 1193±20 K.[17]

The emission spectrum of the planet PDS 70 b is gray and featureless, and no molecular species were detected by 2021.[25]

A second planet, named PDS 70 c, was discovered in 2019 using the VLT's MUSE integral field spectrograph.[26] The planet orbits its host star at a distance of 5.31 billion kilometres (35.5 au), further away than PDS 70 b.[26] PDS 70 c is in a near 1:2 orbital resonance with PDS 70 b, meaning that PDS 70 c completes nearly one revolution once every time PDS 70 b completes nearly two.[26]

Circumplanetary disk[edit]

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.[27][28][29] The disk was confirmed by Caltech-led researchers using the W. M. Keck Observatory in Mauna Kea, whose research was published in May 2020.[30] An image of the circumplanetary disk around PDS 70 c was published in November 2021.[31]

See also[edit]

References[edit]

  1. ^ a b c d e f Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051.
  2. ^ a b Riaud, P.; Mawet, D.; Absil, O.; Boccaletti, A.; Baudoz, P.; Herwats, E.; Surdej, J. (2006). "Coronagraphic imaging of three weak-line T Tauri stars: evidence of planetary formation around PDS 70" (PDF). Astronomy & Astrophysics. 458 (1): 317–325. Bibcode:2006A&A...458..317R. doi:10.1051/0004-6361:20065232.
  3. ^ a b c d e f g h i Keppler, M; et al. (2018). "Discovery of a planetary-mass companion within the gap of the transition disk around PDS 70". Astronomy & Astrophysics. 617: A44. arXiv:1806.11568. Bibcode:2018A&A...617A..44K. doi:10.1051/0004-6361/201832957. S2CID 49562730.
  4. ^ a b Gregorio-Hetem, J.; Hetem, A. (2002). "Classification of a selected sample of weak T Tauri stars". Monthly Notices of the Royal Astronomical Society. 336 (1): 197–206. Bibcode:2002MNRAS.336..197G. doi:10.1046/j.1365-8711.2002.05716.x.
  5. ^ a b c Hashimoto, J.; et al. (2012). "Polarimetric Imaging of Large Cavity Structures in the Pre-Transitional Protoplanetary Disk Around PDS 70: Observations of the Disk". The Astrophysical Journal. 758 (1): L19. arXiv:1208.2075. Bibcode:2012ApJ...758L..19H. doi:10.1088/2041-8205/758/1/L19. S2CID 13691976.
  6. ^ a b Staff (2 July 2018). "First confirmed image of newborn planet caught with ESO's VLT - Spectrum reveals cloudy atmosphere". EurekAlert!. Retrieved 2 July 2018.
  7. ^ a b Müller, A; et al. (2018). "Orbital and atmospheric characterization of the planet within the gap of the PDS 70 transition disk". Astronomy & Astrophysics. 617: L2. arXiv:1806.11567. Bibcode:2018A&A...617L...2M. doi:10.1051/0004-6361/201833584. S2CID 49561725.
  8. ^ "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. Retrieved 8 December 2021.
  9. ^ Sartori, Marılia J.; Gregorio-Hetem, Jane; Rodrigues, Claudia V.; Hetem, Annibal; Batalha, Celso (November 2009). "Analysis of the Pico dos Dias Survey Herbig Ae/Be Candidates". The Astronomical Journal. 139 (1): 27–38. doi:10.1088/0004-6256/139/1/27. Retrieved 5 December 2021.
  10. ^ Gregorio-Hetem, J.; Lepine, J. R. D.; Quast, G. R.; Torres, C. A. O.; de La Reza, R. (February 1992). "A Search for T Tauri Stars Based on the IRAS Point Source Catalog. I." The Astronomical Journal. 103 (2): 549–563. Bibcode:1992AJ....103..549G. doi:10.1086/116082. Retrieved 5 December 2021.
  11. ^ "V1032 Cen". The International Variable Star Index. AAVSO. Retrieved 4 December 2021.
  12. ^ Kiraga, M. (March 2012). "ASAS Photometry of ROSAT Sources. I. Periodic Variable Stars Coincident with Bright Sources from the ROSAT All Sky Survey". Acta Astronomica. 62 (1): 67–95. arXiv:1204.3825. Bibcode:2012AcA....62...67K. Retrieved 4 December 2021.
  13. ^ Batalha, C. C.; Quast, G. R.; Torres, C. A. O.; Pereira, P. C. R.; Terra, M. A. O.; Jablonski, F.; Schiavon, R. P.; de la Reza, J. R.; Sartori, M. J. (March 1998). "Photometric variability of southern T Tauri stars". Astronomy & Astrophysics Supplement Series. 128 (3): 561–571. Bibcode:1998A&AS..128..561B. doi:10.1051/aas:1998163. Retrieved 4 December 2021.
  14. ^ 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.
  15. ^ "Giant Gap PDS 70's Protoplanetary Disk May Indicate Multiple Planets". SciTechDaily. 12 November 2012. Retrieved 30 June 2018.
  16. ^ Hashimoto, J.; et al. (2015). "The Structure of Pre-Transitional Protoplanetary Disks. II. Azimuthal Asymmetries, Different Radial Distributions of Large and Small Dust Grains in PDS 70". The Astrophysical Journal. 799 (1): 43. arXiv:1411.2587. Bibcode:2015ApJ...799...43H. doi:10.1088/0004-637X/799/1/43. S2CID 53389813.
  17. ^ a b Stolker, Tomas; Marleau, Gabriel-Dominique; Cugno, Gabriele; Mollière, Paul; Quanz, Sascha P.; Todorov, Kamen O.; Kühn, Jonas (2020), "MIRACLES: Atmospheric characterization of directly imaged planets and substellar companions at 4–5 μm", Astronomy & Astrophysics, 644: A13, arXiv:2009.04483, doi:10.1051/0004-6361/202038878, S2CID 221586208
  18. ^ Planet PDS 70 c on exoplanet.eu
  19. ^ a b c d Wang, J. J.; et al. (2021), "Constraining the Nature of the PDS 70 Protoplanets with VLTI/GRAVITY ∗", The Astronomical Journal, 161 (3): 148, arXiv:2101.04187, Bibcode:2021AJ....161..148W, doi:10.3847/1538-3881/abdb2d, S2CID 231583118
  20. ^ Clery, D. (2018). "In a first, astronomers witness the birth of a planet from gas and dust". Science. doi:10.1126/science.aau6469. S2CID 134883080.
  21. ^ Christiaens, V.; Cantalloube, F.; Casassus, S.; Price, D.J.; Absil, O.; Pinte, C.; Girard, J.; Montesinos, M. (15 May 2019). "Evidence for a circumplanetary disc around protoplanet PDS 70 b". The Astrophysical Journal. 877 (2): L33. arXiv:1905.06370. Bibcode:2019ApJ...877L..33C. doi:10.3847/2041-8213/ab212b. S2CID 155100321.
  22. ^ Hashimoto, Jun; Aoyama, Yuhiko; Konishi, Mihoko; Uyama, Taichi; Takasao, Shinsuke; Ikoma, Masahiro; Tanigawa, Takayuki (2020). "Accretion Properties of PDS 70b with MUSE". The Astronomical Journal. 159 (5): 222. arXiv:2003.07922. Bibcode:2020AJ....159..222H. doi:10.3847/1538-3881/ab811e. S2CID 212747630.
  23. ^ 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, S2CID 233443901
  24. ^ https://www.nasaspaceflight.com/2021/05/hubble-uv-exoplanet-growth-measured/ ...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.”
  25. ^ 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, S2CID 235358211
  26. ^ a b c "A Pair of Fledgling Planets Directly Seen Growing Around a Young Star". hubblesite.org. NASA. 3 June 2019. Retrieved 3 June 2019.
  27. ^ Isella, Andrea; et al. (11 July 2019). "Detection of Continuum Submillimeter Emission Associated with Candidate Protoplanets". The Astrophysical Journal Letters. 879 (2): L25. arXiv:1906.06308. Bibcode:2019ApJ...879L..25I. doi:10.3847/2041-8213/ab2a12. S2CID 189897829.
  28. ^ Blue, Charles E. (11 July 2019). "'Moon-forming' Circumplanetary Disk Discovered in Distant Star System". National Radio Astronomy Observatory. Retrieved 11 July 2019.
  29. ^ Carne, Nick (13 July 2019). "'Moon-forming' disk found in distant star system - Discovery helps confirm theories of planet formation, astronomers say". Cosmos. Retrieved 12 July 2019.
  30. ^ "Astronomers confirm existence of two giant newborn planets in PDS 70 system". phys.org. Retrieved 20 May 2020.
  31. ^ Parks, Jake (8 November 2021). "Snapshot: ALMA spots moon-forming disk around distant exoplanet - This stellar shot serves as the first unambiguous detection of a circumplanetary disk capable of brewing its own moon". Astronomy. Retrieved 9 November 2021.

External links[edit]