TY - JOUR

T1 - The HARPS-N Rocky Planet Search

T2 - I. HD219134 b: a transiting rocky planet in a multi-planet system at 6.5 pc from the Sun

AU - Motalebi, F.

AU - Udry, S.

AU - Gillon, M.

AU - Lovis, C.

AU - Ségransan, D.

AU - Buchhave, Lars A.

AU - Demory, B. O.

AU - Malavolta, L.

AU - Dressing, C. D.

AU - Sasselov, D.

AU - Rice, K.

AU - Charbonneau, D.

AU - Collier Cameron, A.

AU - Latham, D.

AU - Molinari, E.

AU - Pepe, F.

AU - Affer, L.

AU - Bonomo, A. S.

AU - Cosentino, R.

AU - Dumusque, X.

AU - Figueira, P.

AU - Fiorenzano, A. F M

AU - Gettel, S.

AU - Harutyunyan, A.

AU - Haywood, R. D.

AU - Johnson, J.

AU - Lopez, E.

AU - Lopez-Morales, M.

AU - Mayor, M.

AU - Micela, G.

AU - Mortier, A.

AU - Nascimbeni, V.

AU - Philips, D.

AU - Piotto, G.

AU - Pollacco, D.

AU - Queloz, D.

AU - Sozzetti, A.

AU - Vanderburg, A.

AU - Watson, C. A.

PY - 2015

Y1 - 2015

N2 - We know now from radial velocity surveys and transit space missions that planets only a few times more massive than our Earth are frequent around solar-type stars. Fundamental questions about their formation history, physical properties, internal structure, and atmosphere composition are, however, still to be solved. We present here the detection of a system of four low-mass planets around the bright (V = 5.5) and close-by (6.5 pc) star HD 219134. This is the first result of the Rocky Planet Search programme with HARPS-N on the Telescopio Nazionale Galileo in La Palma. The inner planet orbits the star in 3.0935 ± 0.0003 days, on a quasi-circular orbit with a semi-major axis of 0.0382 ± 0.0003 AU. Spitzer observations allowed us to detect the transit of the planet in front of the star making HD 219134 b the nearest known transiting planet to date. From the amplitude of the radial velocity variation (2.25 ± 0.22 ms-1) and observed depth of the transit (359 ± 38 ppm), the planet mass and radius are estimated to be 4.36 ± 0.44 M⊕ and 1.606 ± 0.086 R⊕, leading to a mean density of 5.76 ± 1.09 g cm-3, suggesting a rocky composition. One additional planet with minimum-mass of 2.78 ± 0.65 M⊕ moves on a close-in, quasi-circular orbit with a period of 6.767 ± 0.004 days. The third planet in the system has a period of 46.66 ± 0.08 days and a minimum-mass of 8.94 ± 1.13 M⊕, at 0.233 ± 0.002 AU from the star. Its eccentricity is 0.46 ± 0.11. The period of this planet is close to the rotational period of the star estimated from variations of activity indicators (42.3 ± 0.1 days). The planetary origin of the signal is, however, thepreferred solution as no indication of variation at the corresponding frequency is observed for activity-sensitive parameters. Finally, a fourth additional longer-period planet of mass of 71 M⊕ orbits the star in 1842 days, on an eccentric orbit (e = 0.34 ± 0.17) at a distance of 2.56 AU.

AB - We know now from radial velocity surveys and transit space missions that planets only a few times more massive than our Earth are frequent around solar-type stars. Fundamental questions about their formation history, physical properties, internal structure, and atmosphere composition are, however, still to be solved. We present here the detection of a system of four low-mass planets around the bright (V = 5.5) and close-by (6.5 pc) star HD 219134. This is the first result of the Rocky Planet Search programme with HARPS-N on the Telescopio Nazionale Galileo in La Palma. The inner planet orbits the star in 3.0935 ± 0.0003 days, on a quasi-circular orbit with a semi-major axis of 0.0382 ± 0.0003 AU. Spitzer observations allowed us to detect the transit of the planet in front of the star making HD 219134 b the nearest known transiting planet to date. From the amplitude of the radial velocity variation (2.25 ± 0.22 ms-1) and observed depth of the transit (359 ± 38 ppm), the planet mass and radius are estimated to be 4.36 ± 0.44 M⊕ and 1.606 ± 0.086 R⊕, leading to a mean density of 5.76 ± 1.09 g cm-3, suggesting a rocky composition. One additional planet with minimum-mass of 2.78 ± 0.65 M⊕ moves on a close-in, quasi-circular orbit with a period of 6.767 ± 0.004 days. The third planet in the system has a period of 46.66 ± 0.08 days and a minimum-mass of 8.94 ± 1.13 M⊕, at 0.233 ± 0.002 AU from the star. Its eccentricity is 0.46 ± 0.11. The period of this planet is close to the rotational period of the star estimated from variations of activity indicators (42.3 ± 0.1 days). The planetary origin of the signal is, however, thepreferred solution as no indication of variation at the corresponding frequency is observed for activity-sensitive parameters. Finally, a fourth additional longer-period planet of mass of 71 M⊕ orbits the star in 1842 days, on an eccentric orbit (e = 0.34 ± 0.17) at a distance of 2.56 AU.

KW - Binaries: eclipsing

KW - Instrumentation: spectrographs

KW - Stars: individual: HD 219134

KW - Techniques: photometric

KW - Techniques: radial velocities

U2 - 10.1051/0004-6361/201526822

DO - 10.1051/0004-6361/201526822

M3 - Journal article

AN - SCOPUS:84946930604

VL - 584

JO - Astronomy & Astrophysics

JF - Astronomy & Astrophysics

SN - 0004-6361

M1 - A72

ER -