Alright, guys and gals. It's time for me to announce a major error in my first OotW. The visual light from proplyd 159-350 is wholly dominated by the young stellar object (YSO) at its center. Alas, the same is true for 170-334 -- the other proplyd I saw. Thus, these are not the brightest proplyds.

I now know that proplyd 159-350 isn’t the brightest one considering that well over 50% of the light we see in visual wavelengths is from the young stellar object (YSO) near its center (and it’s not even the brightest YSO in the Trapezium). It’s taken me a lot of work to come to this conclusion, and I credit professor John Bally (University of Colorado Boulder) with helping me to realize that nearly all the gorgeous images of M42 taken with the Hubble Space Telescope were done through special filters that enhanced the light from the ionized shock front of each protoplanetary disk and dimmed the YSOs that are visible. It’s sorta like viewing the Ring Nebula through an O-III filter. The nebula becomes more prominent while you don’t stand a chance of glimpsing the central star. But without the filter, the true visibility of the central star is revealed.

So where does that leave us? Well, I was going to walk away from this project with my head hung low considering how much research I’ve put in and how I have yet to see more than the YSO of various proplyds. But luckily, the last time I observed M42 with my 16-inch, I redeemed myself. On February 17th, I saw 244-440, a true giant among proplyds. And I know I saw the ionized protoplanetary disk because it was nonstellar at 440x in my 16-inch. NEAT FACT: On that same night, I noticed for the first time how distinctly brown the "E" star was at just 440x...


Proplyd 244-440.jpg
proplyd 244-440 lies 142.3” from Theta1 C and 29” from Theta2 A


So, in my current opinion, the brightest proplyd (which displays more light from its ionized front than the YSO) is 244-440. But I'm not terribly sure which one is the second brightest...though I've got a list of candidates for you all to investigate further. They include 155-338, 177-341, 142-301, 170-249, and 158-327. I will state upfront that the reason I don't have 158-323 (H star), 163-317 (I star), and 167-317 (G star) on that list is because I'm undecided.


Proplyds FINAL.jpg


Proplyds in Visual Wavelengths - Copy.jpg
Above is what I used to come to my conclusion of which proplyds are the brightest


Interesting side story, the 2009 ESA/HST press release mislabeled proplyd 244-440 as 106-417. This led Dave Tosteson to make the same mistake in his Going Deep in the 2021 issue of Sky & Telescope. I've since informed Dave of his error and ESA/NASA. He acknowledged the error while a note was added to the press release image I link to (above).

Thank you all for your time,
Scott H.