WASP-4b
Size comparison of WASP-4b with Jupiter.
Discovery[1]
Discovered byWide Angle Search for Planets
Discovery siteSouth African Astronomical Observatory
Discovery dateOctober 31, 2007
Transit photometry
Orbital characteristics[2]
0.02239±0.00084 AU
Eccentricity<0.0033[3]
1.338231587(22) d
Inclination88.02°±0.69°
Semi-amplitude232.7+2.5
−2.2 m/s[3]
StarWASP-4
Physical characteristics[2]
Mean radius
1.312±0.045 RJ
Mass1.164±0.082 MJ
Mean density
0.639±0.079 g/cm3
Temperature1957±68 K (1,684 °C; 3,063 °F)[4]

    WASP-4b is an exoplanet, specifically a hot Jupiter, approximately 891 light-years away[5] in the constellation of Phoenix.[6]

    Discovery

    The planet was the discovered by the Wide Angle Search for Planets team using images taken with the SuperWASP-South project's eight wide-angle cameras located at the South African Astronomical Observatory.[7][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 planetary equilibrium temperature would be 1650±30 K,[9] but the measured dayside temperature is higher, with a 2015 study finding 1900±100 K[10] and a 2020 study finding 1957±68 K.[4]

    A study in 2012, utilizing the Rossiter–McLaughlin effect, determined the planetary orbit is probably aligned with the equatorial plane of the star, with misalignment equal to -1+14
    −12    °.[11]

    The planet's orbital period appears to be decreasing at a rate of 7.33±0.71 milliseconds per year, suggesting that its orbit is decaying, with a decay timescale of 15.77±1.57 million years. The anomalously high rate of orbital decay of WASP-4b is poorly understood as of 2021.[2]

    References

    1. 1 2 3 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. 1 2 3 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
    3. 1 2 Bonomo, A. S.; Desidera, S.; et al. (June 2017). "The GAPS Programme with HARPS-N at TNG. XIV. Investigating giant planet migration history via improved eccentricity and mass determination for 231 transiting planets". Astronomy & Astrophysics. 602: A107. arXiv:1704.00373. Bibcode:2017A&A...602A.107B. doi:10.1051/0004-6361/201629882. S2CID 118923163.
    4. 1 2 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
    5. ↑ Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
    6. ↑ 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
    7. ↑ Sherriff, Lucy (2007-10-31). "UK boffins ID three new exo-planets". The Register. Retrieved 2018-09-23.
    8. ↑ "Astronomer discovers new planets". BBC News. 2007-10-31. Retrieved 2018-09-23.
    9. ↑ 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.
    10. ↑ 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.
    11. ↑ 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

    Further reading

    Media related to WASP-4b at Wikimedia Commons

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