HD 222259

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HD 222259
DS Tuc A(right)B(left) H+OPEN.png
HD 222259 imaged with the NTT. HD 222259 A is on the right and HD 222259 B is on the left
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Tucana
HD 222259 A
Right ascension  23h 39m 39.48096s[1]
Declination −69° 11′ 44.7093″[1]
Apparent magnitude (V) 8.47[2]
HD 222259 B
Right ascension  23h 39m 39.26995s[1]
Declination –69° 11′ 39.4950″[1]
Apparent magnitude (V) 9.84[3]
Spectral type G6V+K3V[3]
Radial velocity (Rv)8.30±0.2[4] km/s
Proper motion (μ) RA: 79.30[5] mas/yr
Dec.: -67.62[5] mas/yr
Parallax (π)21.89 ± 0.84[5] mas
Distance149 ± 6 ly
(46 ± 2 pc)
HD 222259 A
Mass1.01±0.06[6] M
Radius0.964±0.029[6] R
Luminosity0.725±0.013[6] L
Temperature5428±80[6] K
Age45±4[6] Myr
HD 222259 B
Mass0.84±0.06[6] M
Radius0.864±0.036[6] R
Luminosity0.327±0.010[6] L
Temperature4700±90[6] K
Age45±4[6] Myr
Other designations
DS Tuc, CCDM J23397-6912AB, CD-69°2106, HIP 116748, WDS J23397-6912AB, TIC 410214986, TOI 200
Database references

HD 222259 (DS Tucanae) is a binary star system in the constellation of Tucana. It has an apparent visual magnitude of 8.5,[6] and is a RS Canum Venaticorum variable.[7] The system is notable for being young as a member of the 45 Myr old Tucana-Horologium moving group[8] and for the primary star hosting the confirmed exoplanet DS Tucanae Ab, discovered by TESS.[9][6][10][11]

Stellar System[edit]

HD 222259 is a visual binary.[3] The binary consists of a G6V primary and a K3V secondary separated by 5".[12] Based on radial velocity measurements it was suggested that the secondary itself is a binary, but later studies could not find evidence for this claim.[6]

Physical properties[edit]

High levels of magnetic activity, a strong 6708Å lithium line, and the position on the color-magnitude diagram, slightly above the main sequence, strongly support a young age of the system.[10]

Planetary System[edit]

The DS Tuc A planetary system[6][10]
(in order from star)
Mass Semimajor axis
Orbital period
Eccentricity Inclination Radius
b <1.3 MJ 0.18+0.13
8.138268 89.5+0.34
5.70±0.17 R

DS Tuc Ab is one of the few transiting planets with an age smaller than 100 Myrs. Other examples are K2-33b, V1298 Tauri b and AU Microscopium b. Of these systems DS Tuc is the brightest and it is a good target for atmospheric characterization with JWST. The planet is a super-Neptune or sub-Saturn.[6] The planet might be an inflated planet with an upper mass limit of 20 M.[10] DS Tuc Ab will be observed by ESA's CHEOPS mission to characterize the planet.[13]


  1. ^ a b c d Gaia Collaboration (2018-08-01). "Gaia Data Release 2 - Summary of the contents and survey properties". Astronomy & Astrophysics. 616: A1. arXiv:1804.09365. doi:10.1051/0004-6361/201833051. ISSN 0004-6361.
  2. ^ Høg, E.; Fabricius, C.; Makarov, V. V.; Urban, S.; Corbin, T.; Wycoff, G.; Bastian, U.; Schwekendiek, P.; Wicenec, A. (March 2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics. 355: L27–L30. Bibcode:2000A&A...355L..27H. ISSN 0004-6361.
  3. ^ a b c Torres, G. (August 1988). "Visual Measurements of Southern Double Stars - Part Three". Astrophysics and Space Science. 147 (2): 257–266. Bibcode:1988Ap&SS.147..257T. doi:10.1007/BF00645670. ISSN 0004-640X.
  4. ^ Gontcharov, G. A. (November 2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759–771. arXiv:1606.08053. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065. ISSN 1063-7737.
  5. ^ a b c Leeuwen, F. van (2007-11-01). "Validation of the new Hipparcos reduction". Astronomy & Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. ISSN 0004-6361.
  6. ^ a b c d e f g h i j k l m n o Newton, Elisabeth R.; Mann, Andrew W.; Tofflemire, Benjamin M.; Pearce, Logan; Rizzuto, Aaron C.; Vanderburg, Andrew; Martinez, Raquel A.; Wang, Jason J.; Ruffio, Jean-Baptiste; Kraus, Adam L.; Johnson, Marshall C.; Thao, Pa Chia; Wood, Mackenna L.; Rampalli, Rayna; Nielsen, Eric L.; Collins, Karen A.; Dragomir, Diana; Hellier, Coel; Anderson, D. R.; Barclay, Thomas; Brown, Carolyn; Feiden, Gregory; Hart, Rhodes; Isopi, Giovanni; Kielkopf, John F.; Mallia, Franco; Nelson, Peter; Rodriguez, Joseph E.; Stockdale, Chris; Waite, Ian A.; Wright, Duncan J.; Lissauer, Jack J.; Ricker, George R.; Vanderspek, Roland; Latham, David W.; Seager, S.; Winn, Joshua N.; Jenkins, Jon M.; Bouma, Luke G.; Burke, Christopher J.; Davies, Misty; Fausnaugh, Michael; Li, Jie; Morris, Robert L.; Mukai, Koji; Villaseñor, Joel; Villeneuva, Steven; De Rosa, Robert J.; Macintosh, Bruce; Mengel, Matthew W.; Okumura, Jack; Wittenmyer, Robert A. (July 2019). "TESS Hunt for Young and Maturing Exoplanets (THYME): A Planet in the 45 Myr Tucana-Horologium Association" (PDF). The Astrophysical Journal Letters. 880 (1): L17. Bibcode:2019ApJ...880L..17N. doi:10.3847/2041-8213/ab2988. ISSN 0004-637X.
  7. ^ Samus', N. N.; Goranskii, V. P.; Durlevich, O. V.; Zharova, A. V.; Kazarovets, E. V.; Kireeva, N. N.; Pastukhova, E. N.; Williams, D. B.; Hazen, M. L. (July 2003). "An Electronic Version of the Second Volume of the General Catalogue of Variable Stars with Improved Coordinates". Astronomy Letters. 29 (7): 468–479. Bibcode:2003AstL...29..468S. doi:10.1134/1.1589864. ISSN 1063-7737.
  8. ^ Zuckerman, B.; Webb, R. A. (2000-06-01). "Identification of a Nearby Stellar Association in theHipparcos Catalog: Implications for Recent, Local Star Formation". The Astrophysical Journal. 535 (2): 959. arXiv:astro-ph/0002461. Bibcode:2000ApJ...535..959Z. doi:10.1086/308897. ISSN 0004-637X.
  9. ^ Albright, Charlotte. "Dartmouth Astronomer on Leading Discovery of a New Planet | Dartmouth News". news.dartmouth.edu. Retrieved 2019-12-18.
  10. ^ a b c d Benatti, S.; Nardiello, D.; Malavolta, L.; Desidera, S.; Borsato, L.; Nascimbeni, V.; Damasso, M.; D'Orazi, V.; Mesa, D.; Messina, S.; Esposito, M.; Bignamini, A.; Claudi, R.; Covino, E.; Lovis, C.; Sabotta, S. (October 2019). "A possibly inflated planet around the bright young star DS Tucanae A". Astronomy & Astrophysics. 630: A81. arXiv:1904.01591. Bibcode:2019A&A...630A..81B. doi:10.1051/0004-6361/201935598. ISSN 0004-6361.
  11. ^ "DS Tuc A b". exoplanetarchive.ipac.caltech.edu. Retrieved 2019-12-18.
  12. ^ Torres, C. a. O.; Quast, G. R.; Silva, L. da; Reza, R. de la; Melo, C. H. F.; Sterzik, M. (2006-12-01). "Search for associations containing young stars (SACY) - I. Sample and searching method". Astronomy & Astrophysics. 460 (3): 695–708. arXiv:astro-ph/0609258. Bibcode:2006A&A...460..695T. doi:10.1051/0004-6361:20065602. ISSN 0004-6361.
  13. ^ "AO-1 Programmes - CHEOPS Guest Observers Programme - Cosmos". www.cosmos.esa.int. Retrieved 2019-12-18.