Tag Archives: WASP-134

WASP-134b and WASP-134c: a pair of warm Jupiters

Most of the planets that WASP discovers are “hot Jupiters”, often defined as having an orbital period less than 10 days, though they clump at periods of 3 to 5 days. Occasionally we find “warm Jupiters”, with periods greater than 10 days. There seem to be far fewer of these (and not just because they’re harder to find, which they are, owing to being less likely to transit, because they are further away, and because they produce fewer transits because of the longer periods).

Our latest discovery paper, led by David Anderson, announces the WASP-134 system. An analysis of the radial-velocity observations looks like this:

There are clearly two different cycles from two different planets. Both are warm Jupiters. The inner one (upper panel) has a period just over 10 days while the outer one (lower panel) has a 70-day period. Both orbits are eccentric (the fits are clearly not sinusoids) and both planets have a mass of about one Jupiter.

This is relatively rare. Few systems are known where a shorter-period, Jupiter-mass planet has a Jupiter-mass companion with an orbit as short as 70 days. (Several systems are known where the companion is much further out, with a period of hundreds of days.)

The presence of two such planets makes it unlikely that the inner one got to its present position by the Lidov–Kozai “high eccentricity migration” pathways that are thought to explain many hot Jupiters. Such a pathway for one planet would be disrupted by the presence of the second planet.

This means that it is more likely that the two planets, WASP-134b and WASP-134c, either formed where they are, or moved inwards by “disc migration” mechanisms. Thus the two WASP-134 planets are perhaps a different population, with a different past history, than the majority of the planets found by WASP.