How to Weigh Non-Transiting Exoplanets

At this point, we know very little about the actual masses of the extrasolar planets we've identified so far. The techniques used to study these planets only give astronomers a general idea of the object's mass, and researchers at the Carnegie Institution for Science sought to remedy that in a new study.

Studying planetary masses is made easier if the object being analyzed is a transiting world. This means that it must have an orbit around its parent star that periodically makes it pass in between that star and Earth. In other words, the planet eclipses its parent star at regular intervals.

Of the around 800 exoplanets identified thus far, some are transiting worlds, and have had their masses established with varying degrees of precision. Others, however, are non-transiting objects. In the new study, CIS investigators demonstrated a technique for establishing the mass of such worlds.

In a paper describing the findings, and published in the latest issue of the esteemed Astrophysical Journal Letters, former CIS scientist Mercedes López-Morales explains how she and her team established the mass of a non-transiting exoplanet with great precision.

Planetary scientists need to know an exoplanet's mass in order to determine its density, and figure out whether it is made up of rocky materials or not. The measure can also be used to establish whether the planet is compact or a gas giant, or if it is actually a planet.

An interesting aspect of this type of research is that alien atmospheres have thus far only been detected on transiting exoplanets. López-Morales conducted the work with colleagues Florian Rodler and Ignasi Ribas of the Institute of Space Sciences, ICE (CSIC-IEEC, in Barcelona, Spain).

“This method represents a strong advance in the field of exoplanets. It opens a new path to determine masses of exoplanets and the composition of their atmospheres,” the team leader explains, quoted by Astrobiology Magazine.

In the near future, the research technique could be used to determine the presence of molecules in the atmosphere of non-transiting exoplanets that reveal the existence of lifeforms. Already, the new research method can reveal the existence of carbon monoxide around non-transiting worlds.

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Via: How to Weigh Non-Transiting Exoplanets