Strange moving star!

Look at this star in DECaLS DR9 and then look at the star in SDSS. It has moved! The shape of the star is also different in the different layers.

Ine :stars::dizzy:






That’s great :slight_smile: Gaia says its proper motion is ~ 1 arcsecond per year – so from SDSS in ~2000 to DECaLS in ~2018 it moves a lot!


Regarding the shape of the star- Would the “white” background of the galaxy oversaturate the star pixels and then when it *bizarrely moves, the black background would “clean up” the pixel bleed? So if the galaxy is very distant and the star is part of the Milky Way, would the orbital position of the Earth possibly create the “movement”? I know it’s a long shot, just spitballin’

Very cool! Clearly seen in Wiseview.


Yeah, this is a late M in the 20pc sample. Very fast mover indeed. I think the DR9 shape may be due to an r-band indiviual exposure issue. You’d probably expect some smearing too from such high proper motion if the images are coadds.

That Wiseview that @spcgoat posted is incredible!

Yup, the images are coadds, in this case with data from 2015, 2016, 2017, 2018, and 2019! Different DRs look different first because they include data up to certain dates, and second, later DRs have outlier-rejection code that would clip out the most distant observations.

Right!! Wiseview is so useful for visualizing motion.

Check out Barnard’s Star: [wiseview]

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Seems to be a Brown Dwarf candidate: Abs Mg 16.46, G-RP 1.59.
In VizieR is in " Catalog of M, L, & T dwarfs from PS1 3π Survey (Best+, 2018)
If not already submitted with the TYGO form in BWP9 Program in Zoouniverse, I think it should be.

It’s in the literature already, so definitely shouldn’t be submitted to BYW:P9.

As it happens, its M8.9, so not a brown dwarf. The BD transition tends to occur at ~L3 at field age.

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The BYWP9 rule for NOT submitting is to be in Simbad, and actually this seems to be the case (if the identification is correct with 2MASSW J1421314+182740 – Low-mass Star ) Plx from Gaia DR3 is 52.86 mas, so distance should be about 18.94 psc, so, without reddening correction, this should mean a Gaia G passband abs mag of 16.45, and G-RP is 1.593. The old rule always holds, when you think you’ve found something interesting, someone else has come first…
Thanks for the comment!

I work with the BYW team (i’m actually in the process of writing a paper which includes some discoveries from BYW participants - fingers crossed we get the observing time we proposed for to get some spectra haha).

Always a good idea to submit anything new that is moving. Its incredibly rare for something <20pc with a Gaia parallax to not be known though.

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