Searching for variability and companions to brown dwarfs in NGTS

Brown dwarfs are failed stars - they form like stars, but are the size of Jupiter. These unusual objects never fuse hydrogen into helium, and so once formed, they simply cool and fade.
Due to their low temperatures (~1500 K or cooler) brown dwarfs have atmospheres that are dominated by molecules such as water, methane, ammonia and carbon monoxide as well as metal hydrides. These molecules form clouds which can be seen to change over the rotation period of the brown dwarf (~ few hours) and form and fade away over weeks and months. We still do not how how these clouds form or disintegrate, but we can see the brightness of the brown dwarfs change with time which is thought to be due to these clouds.

The twelve Next Generation Transit Survey (NGTS) telescopes are fully operational in Chile, monitoring tens of thousands of stars every night for evidence of extrasolar planets as small as Neptune. There are many brown dwarfs observed in these fields, however, the standard data reduction pipeline only extracts the brightest stars, missing the brown dwarfs, and other interesting faint objects. In order to look at the brown dwarf lightcurves to monitor their cloud patterns, and also to find any transiting companions to the brown dwarfs (e.g. exoplanets, white dwarfs) we need a pipeline that will extract data for fainter objects. We have months of data on each NGTS field - an unprecedented amount of time to monitor brown dwarfs for variability and to search for exoplanet companions. These long term observations of brown dwarfs will enable us to begin to unlock the secrets of how the clouds change with time in a brown dwarf atmosphere.

In this PhD project you will in the first instance develop a “deep” pipeline to enable the study of light curves from brown dwarfs and late M dwarfs from NGTS. Once this pipeline is operational, you will use it to not only search for brown dwarf variability, but also variability and exoplanets around the coolest M dwarfs (like Trappist 1).