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As we all know, seven earth-like planets have been discovered orbiting the low-mass-star TRAPPIST-1.   TRAPPIST-1 is reported to be located only 12 parsecs (39 light yrs) from us.  Can anyone described how this distance was determined?  Thanks.

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Jordan a common method to measure distance to stars is the parallax method. Essentially triangulation where the position of the star is compared over say a 6 month period.  The other method is effectively by comparison to a standard known reference (standard candles). Here the distance to so called Cepheid variables stars is taken as the reference. I don't know for certain but I suspect that one of either method was used in this case. I believe parallax favours nearby stars.




Edited by saac
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The official web site is www.trappist.one which has a multitude of links to data if you wish to delve deeper.

We were lucky enough to have one of the authors - Dr Amaury Triaud from Cambridge University - speak for us at Norwich Astronomical Society last year about using the moon to help find exo-planets and exo-planet research in general (he wasn't allowed to talk specifically about the Trappist-1 discoveries as they were unpublished at the time but you could tell it was going to be a biggie!)

Dr Triaud is a really good speaker - if you ever get the chance to listen to him I'd heartily recommend it. 


Edited by 101nut
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4 hours ago, Jordan Konisky said:

I thought parallax, but was looking for the actual report.  Thanks, Reggie for that trappist-1 info site which cites the Hipparcos data. 

I believe that CTIOPI has the most recent data for TRAPPIST-1, here you go: http://iopscience.iop.org/article/10.1086/505706/pdf

TRAPPIST-1 is referred to as 2MASS 2306-0502.

Edited by glappkaeft
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