WASP-4b

WASP-4b is an extrasolar planet approximately 891 light-years away[6] in the constellation of Phoenix.[7]

WASP-4b
Size comparison of WASP-4b with Jupiter.
Discovery[1][2]
Discovered byWide Angle Search for Planets
Discovery siteSouth African Astronomical Observatory
Discovery dateOctober 31, 2007
Transit photometry
Orbital characteristics
0.02255+0.00095
−0.00065[3] AU
Eccentricity0.0[3]
1.338231587±0.000000022 [4] d
Inclination89.35+0.64
−0.49[3]
Semi-amplitude247.6+13.9
−6.8[3]
StarWASP-4
Physical characteristics
Mean radius
1.304+0.054
−0.042[3] RJ
Mass1.21+0.13
−0.08[3] MJ
Temperature1900±100[5]

    Discovery

    The planet was the discovered by the Wide Angle Search for Planets team using images taken with the SuperWASP-South projects eight wide-angle cameras located at the South African Astronomical Observatory.[8][1] Analysis of over 4000 images taken between May and November 2006 resulted in the detection of a transit occurring every 1.3 days. Follow-up radial velocity observations using the Swiss 1.2-metre Leonhard Euler Telescope confirmed that the transiting object was a planet.[1]

    The radial velocity trend of WASP-4, caused by the presence of WASP-4 b.

    Characteristics

    The equilibrium planetary temperature would be 1650±30 K,[3] but measured temperature is higher at 1900±100 K.[5] Dayside temperature measured in 2020 is 1957±68 K.[9]

    The study in 2012, utilizing a Rossiter–McLaughlin effect, have determined the planetary orbit is probably aligned with the equatorial plane of the star, misalignment equal to -1+14
    −12    °.[10]

    The orbital period of the planet is decreasing by 7.33±0.71 milliseconds per year, with decay timescale of 15.77±1.57 million years. The anomalously high rate of orbital decay of WASP-4b is poorly understood as in 2021.[4]

    References
    1. Wilson, D. M.; et al. (2008). "WASP-4b: A 12th Magnitude Transiting Hot Jupiter in the Southern Hemisphere". The Astrophysical Journal Letters. 675 (2): L113–L116. arXiv:0801.1509. Bibcode:2008ApJ...675L.113W. doi:10.1086/586735.
    2. "Astronomer discovers new planets". BBC News. 2007-10-31. Retrieved 2018-09-23.
    3. Table 3, Improved parameters for the transiting hot Jupiters WASP-4b and WASP-5b, M. Gillon et al., Astronomy and Astrophysics 496, #1 (2009), pp. 259–267, doi:10.1051/0004-6361:200810929, Bibcode:2009A&A...496..259G.
    4. Turner, Jake D.; Flagg, Laura; Ridden-Harper, Andrew; Jayawardhana, Ray (2022), "Characterizing the WASP-4 System with TESS and Radial Velocity Data: Constraints on the Cause of the Hot Jupiter's Changing Orbit and Evidence of an Outer Planet", The Astronomical Journal, 163 (6): 281, arXiv:2112.09621, Bibcode:2022AJ....163..281T, doi:10.3847/1538-3881/ac686f, S2CID 245329747
    5. Zhou, G.; Bayliss, D. D. R.; Kedziora-Chudczer, L.; Tinney, C. G.; Bailey, J.; Salter, G.; Rodriguez, J. (2015). "Secondary eclipse observations for seven hot-Jupiters from the Anglo-Australian Telescope". Monthly Notices of the Royal Astronomical Society. 454 (3): 3002–3019. arXiv:1509.04147. Bibcode:2015MNRAS.454.3002Z. doi:10.1093/mnras/stv2138.
    6. Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
    7. Roman, Nancy G. (1987). "Identification of a Constellation From a Position". Publications of the Astronomical Society of the Pacific. 99 (617): 695–699. Bibcode:1987PASP...99..695R. doi:10.1086/132034. Vizier query form
    8. Sherriff, Lucy (2007-10-31). "UK boffins ID three new exo-planets". The Register. Retrieved 2018-09-23.
    9. Wong, Ian; Shporer, Avi; Daylan, Tansu; Benneke, Björn; Fetherolf, Tara; Kane, Stephen R.; Ricker, George R.; Vanderspek, Roland; Latham, David W.; Winn, Joshua N.; Jenkins, Jon M.; Boyd, Patricia T.; Glidden, Ana; Goeke, Robert F.; Sha, Lizhou; Ting, Eric B.; Yahalomi, Daniel (2020), "Systematic Phase Curve Study of Known Transiting Systems from Year One of the TESS Mission", The Astronomical Journal, 160 (4): 155, arXiv:2003.06407, Bibcode:2020AJ....160..155W, doi:10.3847/1538-3881/ababad, S2CID 212717799
    10. Albrecht, Simon; Winn, Joshua N.; Johnson, John A.; Howard, Andrew W.; Marcy, Geoffrey W.; Butler, R. Paul; Arriagada, Pamela; Crane, Jeffrey D.; Shectman, Stephen A.; Thompson, Ian B.; Hirano, Teruyuki; Bakos, Gaspar; Hartman, Joel D. (2012), "Obliquities of Hot Jupiter Host Stars: Evidence for Tidal Interactions and Primordial Misalignments", The Astrophysical Journal, 757 (1): 18, arXiv:1206.6105, Bibcode:2012ApJ...757...18A, doi:10.1088/0004-637X/757/1/18, S2CID 17174530

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