WD1856b - A white dwarf exoplanet and JWST target

[robin_astro]

WD 1856b is a Jupiter sized exoplanet in a close orbit around a much smaller white dwarf star, transiting every 1.4 days. (An interesting conundrum is how it managed to avoid being engulfed during  the parent star's red giant phase).  Actually, partially eclipses is perhaps a more apt description as it is a 56% deep grazing event and so is on  the observing list for the JWST to measure the spectrum of the starlight passing through the planet's atmosphere.  Although much deeper than typical exoplanet transits, measuring it did  present some interesting different challenges  due to its faintness (mag 17) and brevity (8 min).  Here is an image of the star in question and my transit measurement. For anyone interested in following up the discovery of this unusual exoplanet and the planned JWST measurements. I have put some more information up on my BAA page

https://britastro.org/observations/observation.php?id=20220106_172719_c34e10f42c4fc746

Cheers

Robin

 

Edited January 11, 2022 by robin_astro

[Peter Reader]

Hi Robin, how did you measure the transit? This is amazing!

[robin_astro]

1 hour ago, Peter Reader said:

how did you measure the transit? 

I got the idea to observe it after watching a video about this being a proposed target for JWST (link on my BAA page). The equipment I used is described on the BAA page. I just took a series of 1 minute exposures and measured the brightness in each one, relative to a non variable star in the same field (a standard technique for measuring variable stars) .The points in the graph are a 3 point moving average to smooth out the noise a bit.  The transit time was from the NASA exoplanet archive website, also linked from the BAA page. This is very different from the usual exoplanet transits where the brightness just drops by a percent or two.  Here it drops by half, but is it also much shorter compared with typical transits which can last for a couple of hours and a rather faint target (white dwarfs are not very luminous because they are so small) The diagram at the top of the graph shows the configuration inferred from the brightness drop but of course we cannot see that from here

Edited February 9, 2022 by robin_astro
clarification

[neil phillips]

Never realized this kind of observation was in reach of amateurs. Very surprised. Impressive Robin

[robin_astro]

White Dwarfs sometimes also "eat" their planets.  The elements they were made up of can be found in the spectrum of the star and detected using amateur equipment.

https://britastro.org/observations/observation.php?id=20210831_232116_04a034fbfd0ae832

Cheers

Robin

[callisto]

Fantastic 👏

Mark.