The well-aligned orbit of WASP-84b: evidence for disk migration of a hot Jupiter

D. R. Anderson; A. H. M. J. Triaud; O. D. Turner; D. J. A. Brown; B. J. M. Clark; B. Smalley; A. Collier Cameron; A. P. Doyle; M. Gillon; C. Hellier; C. Lovis; P. F. L. Maxted; D. Pollacco; D. Queloz; A. M. S. Smith

doi:10.1088/2041-8205/800/1/L9

The well-aligned orbit of WASP-84b: evidence for disk migration of a hot Jupiter

D. R. Anderson, A. H. M. J. Triaud, O. D. Turner, D. J. A. Brown, B. J. M. Clark, B. Smalley, A. Collier Cameron, A. P. Doyle, M. Gillon, C. Hellier, C. Lovis, P. F. L. Maxted, D. Pollacco, D. Queloz, A. M. S. Smith

Physics and Astronomy

Research output: Contribution to journal › Letter › peer-review

Abstract

We report the sky-projected orbital obliquity (spin-orbit angle) of WASP-84b, a 0.69M_Jup planet in an 8.52 day orbit around a G9V/K0V star, to be λ = -0.3 ± 1.7°. We obtain a true obliquity of ψ = 17.3 ± 7.7° from a measurement of the inclination of the stellar spin axis with respect to the sky plane. Due to the young age and the weak tidal forcing of the system, we suggest that the orbit of WASP-84b is unlikely to have both realigned and circularized from the misaligned and/or eccentric orbit likely to have arisen from high-eccentricity migration. Therefore we conclude that the planet probably migrated via interaction with the protoplanetary disk. This would make it the first "hot Jupiter" (P < 10_d) to have been shown to have migrated via this pathway. Further, we argue that the distribution of obliquities for planets orbiting cool stars (T_eff < 6250 K) suggests that high-eccentricity migration is an important pathway for the formation of short-orbit, giant planets.

Original language	English
Article number	L9
Number of pages	6
Journal	Astrophysical Journal Letters
Volume	800
Issue number	1
DOIs	https://doi.org/10.1088/2041-8205/800/1/L9
Publication status	Published - 9 Feb 2015

Keywords

planets and satellites: dynamical evolution and stability
planet–disk interactions
planets and satellites: individual: WASP-84b
planet–star interactions
stars: individual: WASP-84

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Anderson, D. R., Triaud, A. H. M. J., Turner, O. D., Brown, D. J. A., Clark, B. J. M., Smalley, B., Collier Cameron, A., Doyle, A. P., Gillon, M., Hellier, C., Lovis, C., Maxted, P. F. L., Pollacco, D., Queloz, D., & Smith, A. M. S. (2015). The well-aligned orbit of WASP-84b: evidence for disk migration of a hot Jupiter. Astrophysical Journal Letters, 800(1), Article L9. https://doi.org/10.1088/2041-8205/800/1/L9

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title = "The well-aligned orbit of WASP-84b: evidence for disk migration of a hot Jupiter",

abstract = "We report the sky-projected orbital obliquity (spin-orbit angle) of WASP-84b, a 0.69MJup planet in an 8.52 day orbit around a G9V/K0V star, to be λ = -0.3 ± 1.7°. We obtain a true obliquity of ψ = 17.3 ± 7.7° from a measurement of the inclination of the stellar spin axis with respect to the sky plane. Due to the young age and the weak tidal forcing of the system, we suggest that the orbit of WASP-84b is unlikely to have both realigned and circularized from the misaligned and/or eccentric orbit likely to have arisen from high-eccentricity migration. Therefore we conclude that the planet probably migrated via interaction with the protoplanetary disk. This would make it the first {"}hot Jupiter{"} (P < 10d) to have been shown to have migrated via this pathway. Further, we argue that the distribution of obliquities for planets orbiting cool stars (Teff < 6250 K) suggests that high-eccentricity migration is an important pathway for the formation of short-orbit, giant planets. ",

keywords = "planets and satellites: dynamical evolution and stability, planet–disk interactions, planets and satellites: individual: WASP-84b, planet–star interactions, stars: individual: WASP-84",

author = "Anderson, {D. R.} and Triaud, {A. H. M. J.} and Turner, {O. D.} and Brown, {D. J. A.} and Clark, {B. J. M.} and B. Smalley and {Collier Cameron}, A. and Doyle, {A. P.} and M. Gillon and C. Hellier and C. Lovis and Maxted, {P. F. L.} and D. Pollacco and D. Queloz and Smith, {A. M. S.}",

year = "2015",

month = feb,

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doi = "10.1088/2041-8205/800/1/L9",

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journal = "Astrophysical Journal Letters",

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Anderson, DR, Triaud, AHMJ, Turner, OD, Brown, DJA, Clark, BJM, Smalley, B, Collier Cameron, A, Doyle, AP, Gillon, M, Hellier, C, Lovis, C, Maxted, PFL, Pollacco, D, Queloz, D & Smith, AMS 2015, 'The well-aligned orbit of WASP-84b: evidence for disk migration of a hot Jupiter', Astrophysical Journal Letters, vol. 800, no. 1, L9. https://doi.org/10.1088/2041-8205/800/1/L9

TY - JOUR

T1 - The well-aligned orbit of WASP-84b

T2 - evidence for disk migration of a hot Jupiter

AU - Anderson, D. R.

AU - Triaud, A. H. M. J.

AU - Turner, O. D.

AU - Brown, D. J. A.

AU - Clark, B. J. M.

AU - Smalley, B.

AU - Collier Cameron, A.

AU - Doyle, A. P.

AU - Gillon, M.

AU - Hellier, C.

AU - Lovis, C.

AU - Maxted, P. F. L.

AU - Pollacco, D.

AU - Queloz, D.

AU - Smith, A. M. S.

PY - 2015/2/9

Y1 - 2015/2/9

N2 - We report the sky-projected orbital obliquity (spin-orbit angle) of WASP-84b, a 0.69MJup planet in an 8.52 day orbit around a G9V/K0V star, to be λ = -0.3 ± 1.7°. We obtain a true obliquity of ψ = 17.3 ± 7.7° from a measurement of the inclination of the stellar spin axis with respect to the sky plane. Due to the young age and the weak tidal forcing of the system, we suggest that the orbit of WASP-84b is unlikely to have both realigned and circularized from the misaligned and/or eccentric orbit likely to have arisen from high-eccentricity migration. Therefore we conclude that the planet probably migrated via interaction with the protoplanetary disk. This would make it the first "hot Jupiter" (P < 10d) to have been shown to have migrated via this pathway. Further, we argue that the distribution of obliquities for planets orbiting cool stars (Teff < 6250 K) suggests that high-eccentricity migration is an important pathway for the formation of short-orbit, giant planets.

AB - We report the sky-projected orbital obliquity (spin-orbit angle) of WASP-84b, a 0.69MJup planet in an 8.52 day orbit around a G9V/K0V star, to be λ = -0.3 ± 1.7°. We obtain a true obliquity of ψ = 17.3 ± 7.7° from a measurement of the inclination of the stellar spin axis with respect to the sky plane. Due to the young age and the weak tidal forcing of the system, we suggest that the orbit of WASP-84b is unlikely to have both realigned and circularized from the misaligned and/or eccentric orbit likely to have arisen from high-eccentricity migration. Therefore we conclude that the planet probably migrated via interaction with the protoplanetary disk. This would make it the first "hot Jupiter" (P < 10d) to have been shown to have migrated via this pathway. Further, we argue that the distribution of obliquities for planets orbiting cool stars (Teff < 6250 K) suggests that high-eccentricity migration is an important pathway for the formation of short-orbit, giant planets.

KW - planets and satellites: dynamical evolution and stability

KW - planet–disk interactions

KW - planets and satellites: individual: WASP-84b

KW - planet–star interactions

KW - stars: individual: WASP-84

U2 - 10.1088/2041-8205/800/1/L9

DO - 10.1088/2041-8205/800/1/L9

M3 - Letter

SN - 2041-8205

VL - 800

JO - Astrophysical Journal Letters

JF - Astrophysical Journal Letters

IS - 1

M1 - L9

ER -

The well-aligned orbit of WASP-84b: evidence for disk migration of a hot Jupiter

Abstract

Keywords

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