# Spin–orbit alignment of exoplanet systems: ensemble analysis using asteroseismology

Research output: Contribution to journalArticlepeer-review

## Standard

Spin–orbit alignment of exoplanet systems: ensemble analysis using asteroseismology. / Campante, T. L.; Lund, M. N.; Kuszlewicz, J. S.; Chaplin, W. J.; Albrecht, S.; Winn, J. N.; Bedding, T. R.; Benomar, O.; Bossini, D.; Handberg, R.; Santos, A. R. G.; Van Eylen, V.; Basu, S.; Christensen-dalsgaard, J.; Elsworth, Y. P.; Hekker, S.; Hirano, T.; Huber, D.; Karoff, C.; Kjeldsen, H.; Lundkvist, M. S.; North, T. S. H.; Silva Aguirre, V.; Stello, D.; White, T. R.

In: The Astrophysical Journal, Vol. 819, No. 1, 01.03.2016.

Research output: Contribution to journalArticlepeer-review

## Harvard

Campante, TL, Lund, MN, Kuszlewicz, JS, Chaplin, WJ, Albrecht, S, Winn, JN, Bedding, TR, Benomar, O, Bossini, D, Handberg, R, Santos, ARG, Van Eylen, V, Basu, S, Christensen-dalsgaard, J, Elsworth, YP, Hekker, S, Hirano, T, Huber, D, Karoff, C, Kjeldsen, H, Lundkvist, MS, North, TSH, Silva Aguirre, V, Stello, D & White, TR 2016, 'Spin–orbit alignment of exoplanet systems: ensemble analysis using asteroseismology', The Astrophysical Journal, vol. 819, no. 1. https://doi.org/10.3847/0004-637X/819/1/85

## APA

Campante, T. L., Lund, M. N., Kuszlewicz, J. S., Chaplin, W. J., Albrecht, S., Winn, J. N., Bedding, T. R., Benomar, O., Bossini, D., Handberg, R., Santos, A. R. G., Van Eylen, V., Basu, S., Christensen-dalsgaard, J., Elsworth, Y. P., Hekker, S., Hirano, T., Huber, D., Karoff, C., ... White, T. R. (2016). Spin–orbit alignment of exoplanet systems: ensemble analysis using asteroseismology. The Astrophysical Journal, 819(1). https://doi.org/10.3847/0004-637X/819/1/85

## Author

Campante, T. L. ; Lund, M. N. ; Kuszlewicz, J. S. ; Chaplin, W. J. ; Albrecht, S. ; Winn, J. N. ; Bedding, T. R. ; Benomar, O. ; Bossini, D. ; Handberg, R. ; Santos, A. R. G. ; Van Eylen, V. ; Basu, S. ; Christensen-dalsgaard, J. ; Elsworth, Y. P. ; Hekker, S. ; Hirano, T. ; Huber, D. ; Karoff, C. ; Kjeldsen, H. ; Lundkvist, M. S. ; North, T. S. H. ; Silva Aguirre, V. ; Stello, D. ; White, T. R. / Spin–orbit alignment of exoplanet systems: ensemble analysis using asteroseismology. In: The Astrophysical Journal. 2016 ; Vol. 819, No. 1.

## Bibtex

@article{cf6bc443ea50422ca838fab07b77e1f4,
title = "Spin–orbit alignment of exoplanet systems: ensemble analysis using asteroseismology",
abstract = "The angle ψ between a planet's orbital axis and the spin axis of its parent star is an important diagnostic of planet formation, migration, and tidal evolution. We seek empirical constraints on ψ by measuring the stellar inclination is via asteroseismology for an ensemble of 25 solar-type hosts observed with NASA's Kepler satellite. Our results for is are consistent with alignment at the 2σ level for all stars in the sample, meaning that the system surrounding the red-giant star Kepler-56 remains as the only unambiguous misaligned multiple-planet system detected to date. The availability of a measurement of the projected spin–orbit angle λ for two of the systems allows us to estimate ψ. We find that the orbit of the hot Jupiter HAT-P-7b is likely to be retrograde ($\psi =116\buildrel{\circ}\over{.} {4}_{-14.7}^{+30.2}$), whereas that of Kepler-25c seems to be well aligned with the stellar spin axis ($\psi =12\buildrel{\circ}\over{.} {6}_{-11.0}^{+6.7}$). While the latter result is in apparent contradiction with a statement made previously in the literature that the multi-transiting system Kepler-25 is misaligned, we show that the results are consistent, given the large associated uncertainties. Finally, we perform a hierarchical Bayesian analysis based on the asteroseismic sample in order to recover the underlying distribution of ψ. The ensemble analysis suggests that the directions of the stellar spin and planetary orbital axes are correlated, as conveyed by a tendency of the host stars to display large values of inclination.",
author = "Campante, {T. L.} and Lund, {M. N.} and Kuszlewicz, {J. S.} and Chaplin, {W. J.} and S. Albrecht and Winn, {J. N.} and Bedding, {T. R.} and O. Benomar and D. Bossini and R. Handberg and Santos, {A. R. G.} and {Van Eylen}, V. and S. Basu and J. Christensen-dalsgaard and Elsworth, {Y. P.} and S. Hekker and T. Hirano and D. Huber and C. Karoff and H. Kjeldsen and Lundkvist, {M. S.} and North, {T. S. H.} and {Silva Aguirre}, V. and D. Stello and White, {T. R.}",
year = "2016",
month = mar,
day = "1",
doi = "10.3847/0004-637X/819/1/85",
language = "English",
volume = "819",
journal = "The Astrophysical Journal",
issn = "0004-637X",
publisher = "Institute of Physics Publishing Ltd",
number = "1",

}

## RIS

TY - JOUR

T1 - Spin–orbit alignment of exoplanet systems: ensemble analysis using asteroseismology

AU - Campante, T. L.

AU - Lund, M. N.

AU - Kuszlewicz, J. S.

AU - Chaplin, W. J.

AU - Albrecht, S.

AU - Winn, J. N.

AU - Bedding, T. R.

AU - Benomar, O.

AU - Bossini, D.

AU - Handberg, R.

AU - Santos, A. R. G.

AU - Van Eylen, V.

AU - Basu, S.

AU - Christensen-dalsgaard, J.

AU - Elsworth, Y. P.

AU - Hekker, S.

AU - Hirano, T.

AU - Huber, D.

AU - Karoff, C.

AU - Kjeldsen, H.

AU - Lundkvist, M. S.

AU - North, T. S. H.

AU - Silva Aguirre, V.

AU - Stello, D.

AU - White, T. R.

PY - 2016/3/1

Y1 - 2016/3/1

N2 - The angle ψ between a planet's orbital axis and the spin axis of its parent star is an important diagnostic of planet formation, migration, and tidal evolution. We seek empirical constraints on ψ by measuring the stellar inclination is via asteroseismology for an ensemble of 25 solar-type hosts observed with NASA's Kepler satellite. Our results for is are consistent with alignment at the 2σ level for all stars in the sample, meaning that the system surrounding the red-giant star Kepler-56 remains as the only unambiguous misaligned multiple-planet system detected to date. The availability of a measurement of the projected spin–orbit angle λ for two of the systems allows us to estimate ψ. We find that the orbit of the hot Jupiter HAT-P-7b is likely to be retrograde ($\psi =116\buildrel{\circ}\over{.} {4}_{-14.7}^{+30.2}$), whereas that of Kepler-25c seems to be well aligned with the stellar spin axis ($\psi =12\buildrel{\circ}\over{.} {6}_{-11.0}^{+6.7}$). While the latter result is in apparent contradiction with a statement made previously in the literature that the multi-transiting system Kepler-25 is misaligned, we show that the results are consistent, given the large associated uncertainties. Finally, we perform a hierarchical Bayesian analysis based on the asteroseismic sample in order to recover the underlying distribution of ψ. The ensemble analysis suggests that the directions of the stellar spin and planetary orbital axes are correlated, as conveyed by a tendency of the host stars to display large values of inclination.

AB - The angle ψ between a planet's orbital axis and the spin axis of its parent star is an important diagnostic of planet formation, migration, and tidal evolution. We seek empirical constraints on ψ by measuring the stellar inclination is via asteroseismology for an ensemble of 25 solar-type hosts observed with NASA's Kepler satellite. Our results for is are consistent with alignment at the 2σ level for all stars in the sample, meaning that the system surrounding the red-giant star Kepler-56 remains as the only unambiguous misaligned multiple-planet system detected to date. The availability of a measurement of the projected spin–orbit angle λ for two of the systems allows us to estimate ψ. We find that the orbit of the hot Jupiter HAT-P-7b is likely to be retrograde ($\psi =116\buildrel{\circ}\over{.} {4}_{-14.7}^{+30.2}$), whereas that of Kepler-25c seems to be well aligned with the stellar spin axis ($\psi =12\buildrel{\circ}\over{.} {6}_{-11.0}^{+6.7}$). While the latter result is in apparent contradiction with a statement made previously in the literature that the multi-transiting system Kepler-25 is misaligned, we show that the results are consistent, given the large associated uncertainties. Finally, we perform a hierarchical Bayesian analysis based on the asteroseismic sample in order to recover the underlying distribution of ψ. The ensemble analysis suggests that the directions of the stellar spin and planetary orbital axes are correlated, as conveyed by a tendency of the host stars to display large values of inclination.

U2 - 10.3847/0004-637X/819/1/85

DO - 10.3847/0004-637X/819/1/85

M3 - Article

VL - 819

JO - The Astrophysical Journal

JF - The Astrophysical Journal

SN - 0004-637X

IS - 1

ER -