For the last two weeks I'd been making the 40 mile drive to work between 5:15 AM - 6:00 AM. By the middle of that drive the first hint of dawn had been showing in the east, and by the time I'd arrived it was starting to get light outside but was still dark enough for a lot of stars to be seen. I was treated to great views of Jupiter blazing away in Taurus and Venus much lower in the east in Gemini, but what really made those morning drives memorable were the views I had of my favorite constellation rising over the east-southeast horizon, Orion. This great collection of bright stars would clear the horizon just as dawn was breaking. It reminded me that the new season for looking at the variable stars in this constellation had officially begun!
Orion is more than an awesome sight in the sky to me. The reason why it contains so many bright stars packed into one area of the sky is because we're looking at a region of our galaxy where giant, white-hot stars are being born from gas and dust clouds. Many of the stars that we can see are just millions - not billions - of years old, and this constellation is absolutely packed with interesting variables! There are dozens of YSO's (Young Stellar Objects)to be watched here. Some of them are difficult objects since they lie within the glow of the Great Orion Nebula M-42 (the fuzzy-looking glow in the middle of the "Sword of Orion") and estimating their brightness is tricky. But many others lie away from that glow, and they can show rapid changes.
Young Stellar Objects are, to put it simply, new-born stars. They're in the last stages of condensing from the gas and dust clouds that collapsed under gravity to form them. They show brightness changes for different reasons and not all of these are well-understood. It's thought that many of these stars still have rings of gas and dust circling them, and when a "glob" of this matter passes between the star's disk and our line of sight, the star seems to fade away and re-brighten. Some observers have reported deep fades and re-brightenings in just hours. I'd love to catch one in the act of doing this! It's also theorized that some of the gas and dust falls onto the surface of the star and ignites it, making it appear to get brighter rapidly to us. There may also be giant star-spots on the surfaces of these stars (like giant versions of sunspots on our Sun) that rotate in and out of view as the star spins on its axis. You just never know what to expect, night after night, when you observe the YSO's in this constellation!
My favorite YSO in Orion so far is UX Orionis. I've been watching this star off and on for three years, and I've seen it brighten from 8th magnitude (very easy to see in my 10" scope) and then dim to 12th magnitude (much more difficult to make out through the 10" telescope). It's done this trick in a two week span of time before, and whether it gets brighter or dimmer from one night to the next is unpredictable. UX Orionis lies just a few degrees northwest of the bright star Rigel. The Orion Nebula M-42 has dozens of stars like this, but the one to watch to me is T Orionis. Also, just to the west of the Belt of Orion there is a very under-observed star called NSV 1960. I haven't been able to find much information about it through internet searches, but the AAVSO Website gives it a wide range in brightness and not much else to back this information up. I'm going to try to make NSV 1960 a priority target this season.
YSO brightness estimates are valuable since these stars are so poorly understood, and only a dozen or so amateurs in the world seem to be watching them systematically. Now that I'm going to be up late at night (instead of getting up early) for the rest of August, I'm hoping that some pre-dawn observing of the Orion YSO stars will be especially valuable to researchers. I'm also hoping that this re-starts my amateur astronomy hobby after being away from the telescope for all these months.
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