TY - JOUR
T1 - HD 28109 hosts a trio of transiting Neptunian planets including a near-resonant pair, confirmed by ASTEP from Antarctica
AU - Dransfield, Georgina
AU - Triaud, Amaury H. M. J.
AU - Guillot, Tristan
AU - Mekarnia, Djamel
AU - Nesvorný, David
AU - Crouzet, Nicolas
AU - Abe, Lyu
AU - Agabi, Karim
AU - Buttu, Marco
AU - Cabrera, Juan
AU - Gandolfi, Davide
AU - Günther, Maximilian N.
AU - Rodler, Florian
AU - Schmider, François-Xavier
AU - Stee, Philippe
AU - Suarez, Olga
AU - Collins, Karen A.
AU - Dévora-Pajares, Martín
AU - Howell, Steve B.
AU - Matthews, Elisabeth C.
AU - Standing, Matthew R.
AU - Stassun, Keivan G.
AU - Stockdale, Chris
AU - Quinn, Samuel N.
AU - Ziegler, Carl
AU - Crossfield, Ian J. M.
AU - Lissauer, Jack J.
AU - Mann, Andrew W.
AU - Matson, Rachel
AU - Schlieder, Joshua
AU - Zhou, George
N1 - 19 pages, 14 figures
PY - 2022/5/23
Y1 - 2022/5/23
N2 - We report on the discovery and characterisation of three planets orbiting the F8 star HD 28109, which sits comfortably in TESS’s continuous viewing zone. The two outer planets have periods of 56.0067±0.0003 days and 84.2597+0.0010−0.0008 days, which implies a period ratio very close to that of the first-order 3:2 mean motion resonance, exciting transit timing variations (TTVs) of up to 60mins. These two planets were first identified by TESS, and we identified a third planet in the TESS photometry with a period of 22.8911±0.0004 days. We confirm the planetary nature of all three planetary candidates using ground-based photometry from Hazelwood, ASTEP and LCO, including a full detection of the ∼9h transit of HD 28109 c from Antarctica. The radii of the three planets are Rb=2.199+0.098−0.10 R⊕, Rc=4.23±0.11 R⊕ and Rd=3.25±0.11 R⊕; we characterise their masses using TTVs and precise radial velocities from ESPRESSO and HARPS, and find them to be Mb=18.5+9.1−7.6 M⊕, Mc=7.9+4.2−3.0 M⊕ and Md=5.7+2.7−2.1 M⊕, making planet b a dense, massive planet while c and d are both under-dense. We also demonstrate that the two outer planets are ripe for atmospheric characterisation using transmission spectroscopy, especially given their position in the CVZ of JWST. The data obtained to date are consistent with resonant (librating) and non-resonant (circulating) solutions; additional observations will show whether the pair is actually locked in resonance or just near-resonant.
AB - We report on the discovery and characterisation of three planets orbiting the F8 star HD 28109, which sits comfortably in TESS’s continuous viewing zone. The two outer planets have periods of 56.0067±0.0003 days and 84.2597+0.0010−0.0008 days, which implies a period ratio very close to that of the first-order 3:2 mean motion resonance, exciting transit timing variations (TTVs) of up to 60mins. These two planets were first identified by TESS, and we identified a third planet in the TESS photometry with a period of 22.8911±0.0004 days. We confirm the planetary nature of all three planetary candidates using ground-based photometry from Hazelwood, ASTEP and LCO, including a full detection of the ∼9h transit of HD 28109 c from Antarctica. The radii of the three planets are Rb=2.199+0.098−0.10 R⊕, Rc=4.23±0.11 R⊕ and Rd=3.25±0.11 R⊕; we characterise their masses using TTVs and precise radial velocities from ESPRESSO and HARPS, and find them to be Mb=18.5+9.1−7.6 M⊕, Mc=7.9+4.2−3.0 M⊕ and Md=5.7+2.7−2.1 M⊕, making planet b a dense, massive planet while c and d are both under-dense. We also demonstrate that the two outer planets are ripe for atmospheric characterisation using transmission spectroscopy, especially given their position in the CVZ of JWST. The data obtained to date are consistent with resonant (librating) and non-resonant (circulating) solutions; additional observations will show whether the pair is actually locked in resonance or just near-resonant.
KW - astro-ph.EP
KW - planets and satellites: detection
KW - planets and satellites: dynamical evolution and stability
KW - planets and satellites: fundamental parameters
UR - http://www.scopus.com/inward/record.url?scp=85135375086&partnerID=8YFLogxK
U2 - 10.1093/mnras/stac1383
DO - 10.1093/mnras/stac1383
M3 - Article
SN - 0035-8711
VL - 515
SP - 1328
EP - 1345
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
IS - 1
M1 - stac1383
ER -