HATS59b,c: A Transiting Hot Jupiter and A Cold Massive Giant Planet Around A Sun-Like Star
HATS59b,c: A Transiting Hot Jupiter and A Cold Massive Giant Planet Around A Sun-Like Star
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Abstract
Abstract
We report the first discovery of a multi-planetary system by the HATSouth network, HATS-59b,c, a planetary system with an inner transiting hot Jupiter and an outer cold massive giant planet, which was detected via radial velocity. The inner transiting planet, HATS-59b, is on an eccentric orbit with e = 0.129 ± 0.049, orbiting a V = 13.951 ± 0.030 mag solar-like star (M⋆ = 1.038 ± 0.039 M⊙ and R⋆ = 1.036 ± 0.067 R⊙) with a period of 5.416081 ± 0.000016 days. The outer companion, HATS-59c is on a circular orbit with m sin i = 12.70 ± 0.87 MJ and a period of 1422 ± 14 days. The inner planet has a mass of 0.806 ± 0.069 MJ and a radius of 1.126 ± 0.077 RJ , yielding a density of 0.70 ± 0.16 gcm−3. Unlike most of the planetary systems that include only a single hot Jupiter, HATS-59b,c includes, in addition to the transiting hot Jupiter, a massive outer companion. The architecture of this system is valuable for understanding planet migration.
High precision RV measurements with the best-fit two-planet orbit model as a function of time.
Phase folded RV light curves of the outer (top) and inner (bottom) planets.
Planetary mass versus a/aroche for single planets (small gray circles), known multi-planetary systems (blue circles), and systems showing a linear trend (green triangles). HATS-59b is shown as a red square. Most of the multi-planetary systems have a/aroche > 2, which supports the high eccentricity migration scenario.
Hot Jupiters are thought to form beyond the iceline and migrate inwards via disk or high-eccentricity migration where the latter is caused by a third planetary or stellar body. Searching therefore for long period companions to close-in hot Jupiters is important to put constraints on the different migration mechanisms. Here, we report the discovery of the first multi-planetary system discovered by the HATSouth survey. The inner planet (HATS-59b) is a transiting hot Jupiter on an eccentric orbit with a period of 5 days and the outer planet (HATS-59c) is a cool massive giant planet on a circular orbit with a period of 1422 days. Comparing HATS-59c to all the detected planetary companions with a full resolved orbit, it has the third longest period, indicating how few outer companions to transiting hot Jupiters have been characterised due to lack of radial velocity observations.
Hot Jupiters are thought to form beyond the iceline and migrate inwards via disk or high-eccentricity migration where the latter is caused by a third planetary or stellar body. Searching therefore for long period companions to close-in hot Jupiters is important to put constraints on the different migration mechanisms. Here, we report the discovery of the first multi-planetary system discovered by the HATSouth survey. The inner planet (HATS-59b) is a transiting hot Jupiter on an eccentric orbit with a period of 5 days and the outer planet (HATS-59c) is a cool massive giant planet on a circular orbit with a period of 1422 days. Comparing HATS-59c to all the detected planetary companions with a full resolved orbit, it has the third longest period, indicating how few outer companions to transiting hot Jupiters have been characterised due to lack of radial velocity observations.
Disk migration predicts that planets can migrate up until aroche, whereas high-eccentricity migration predicts that planets will circularize at a semimajor axis greater than 2aroche. The top Figure indicate that high-eccentricity migration could be the main mechanism for placing the gas giants on a close-in orbit.
Disk migration predicts that planets can migrate up until aroche, whereas high-eccentricity migration predicts that planets will circularize at a semimajor axis greater than 2aroche. The top Figure indicate that high-eccentricity migration could be the main mechanism for placing the gas giants on a close-in orbit.
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