2014 UN271: cometary activity


Luca Buzzi
 

Dear all,
we imaged it tonight with the 0.51-m SkyGems Remote Telescope in Namibia (45 x 90 seconds) and it has a clear cometary activity, with a 15" coma possibly elongated in PA between 0 and 90°.
Its magnitude is 19.7 G with an aperture radius of 4.5", and 18.8 G with an aperture of 7.5". Here you can see a cropped image:

https://www.astrogeo.va.it/astronomia/2014UN271_20210622_L81.png

Regards,
Luca Buzzi - MPC 204
Andrea Aletti - MPC 204
Lukas Demetz - MPC L81

Il 19/06/2021 08:48, Sam Deen via groups.io ha scritto:
Hi all,
Some very recent exciting news from the Dark Energy Survey collaboration ( https://minorplanetcenter.net/mpec/K21/K21M53.html <https://minorplanetcenter.net/mpec/K21/K21M53.html> )
This new object, 2014 UN271, is not just unusual, but radically exceptional among all known bodies in the Solar System to date. Discovered about 29 AU out from the Sun and currently around 22 away, its orbit takes it from just beyond the orbit of Saturn (10.9 AU) all the way out to the Oort Cloud - no, not the Hill Cloud. the Oort Cloud. The incoming barycentric aphelion was 39,400 +/- 1200 AU, and outgoing it will be an even huger 54,600 +/- 2300 AU (!!)
   Peribarion 2031 Jan 21.574596 +/- 0.0666 TT = 13:47:25 (JD 2462888.074596)
Epoch 1000 Jan  1.0 TT = JDT 2086307.5                        Find_Orb
M 359.86589747 +/- 0.006            (J2000 ecliptic)
n   0.00000035 +/- 1.73e-8          Peri.  326.27934 +/- 0.0006
a  19721.6906 +/- 665               Node   190.00285 +/- 0.000052
e   0.9994448 +/- 1.81e-5           Incl.   95.46628 +/- 0.000052
P2767738                   H  7.8   G  0.15   U  0.7
q 10.9491955 +/- 0.000177    Q 39432.4321 +/- 1232
From 37 observations 2014 Aug. 28-2018 Nov. 8; mean residual 0".07
   Peribarion 2031 Jan 21.542640 +/- 0.0662 TT = 13:01:24 (JD 2462888.042640)
Epoch 3000 Jan  1.0 TT = JDT 2816787.5                        Find_Orb
M   0.07733589 +/- 0.0053           (J2000 ecliptic)
n   0.00000021 +/- 1.47e-8          Peri.  326.24537 +/- 0.0006
a  27310.4810 +/- 1288              Node   190.00938 +/- 0.000052
e   0.9995990 +/- 1.82e-5           Incl.   95.46057 +/- 0.000052
P4510273                   H  7.8   G  0.15   U  0.6
q 10.9490073 +/- 0.000177    Q 54610.0131 +/- 2312
From 37 observations 2014 Aug. 28-2018 Nov. 8; mean residual 0".07
Based on the given absolute magnitude, and given how exceptionally red it looked in 2014 precovery images from CFHT (the g - r color was 0.9, and r - i was 0.5!) I would estimate at an albedo of 0.01-0.08 a diameter of 130-370 kilometers (nominally 160) which puts it on a similar scale, if not larger than, Sarabat's huge comet C/1729 P1, and almost undoubtedly the largest Oort Cloud object ever discovered- almost in dwarf planet territory!
I have little doubt in my mind that as this gets closer to the Sun, it will begin displaying the coma and tail typical of every other object yet seen in its orbit. It almost feels premature to ascribe any sort of theoretical slope to it with how little precedent there is for objects like this, but if Hale-Bopp is any indication with its slope of 20 at large distances, then 2014 UN271 could possibly reach magnitude 13 in early 2031 - but I wouldn't count on much brighter than 16 or 17 just yet. Either way, that's impressively bright, and this object should make an exceptional target of study in the next couple of decades to accompany how exceptional an object it looks to be.
~Sam

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