YSO's (Young Stellar Objects)

  In my posts I often refer to "YSO stars" so I thought it might be good to give a little background information about them. 

  YSO stands for "Young Stellar Object." The long-standing theory is that these are stars that are still condensing from dust and gas, and by astronomical standards they are very young; on the order of just millions of years old instead of billions of years old like our Sun. Classifying them is difficult because they come in all sizes and types. The one thing they have in common is that they usually show a lot of unpredictable brightness changes, for a lot of different reasons. Since these stars are surrounded by gas and dust, they often fade quickly in brightness and recover because the ring of dust is "clumpy" and a thick patch of dust orbiting the star might float in between our line of sight and the star. Also, if a lot of gas and dust falls into the star, this can make it suddenly get brighter as the new material ignites on the surface.

  I've looked at a couple of YSO stars for years. Just after high school, one of the stars I used to report to the AAVSO (American Association of Variable Star Observers) was called T Tauri. I also made estimates for some of the interesting stars buried in the glow of the Orion Nebula. But most of the variable stars I observed and reported to the AAVSO were long-term variables like Mira stars and Semi-Regulars. I still observe these, but my interest focused on YSO observing about a year ago. For the last decade, there have been several automatic sky surveys created. These are robotic telescopes that image huge chunks of the sky every few days and automatically record star brightness. Though the all-sky automatic surveys are a boon for science, I was starting to get the feeling that observing long-period variable stars by eye was getting obsolete because of them. I wanted to start an observing program where I could still provide valuable data. 

  In the spring of 2010, I started to realize that YSO stars weren't being studied by very many people, and that they showed brightness changes that were so fast that a lot of the automatic sky surveys missed them. I started emailing around asking if anyone observed them regularly, and this was how I struck up a pen-pal relationship via email with Mike Poxon from Norwich, England. Mike had been observing these kinds of stars for years and confirmed my suspicions; that few amateur astronomers looked at them regularly, that they were getting increasing attention from professional astronomers, and that they showed a lot of wild short-term dimming and "flickering" that was too fast for the automated surveys to catch! Mike kindly provided me with lists of Young Stellar Object targets in range of my telescope and also with charts that showed these variables and comparison stars to estimate their brightness by. He continues to serve as my unofficial "mentor" when it comes to gathering data about these stars and provides prompt answers to my stupid questions about observing them. For this I am eternally grateful! 

  Recently, Mike Poxon emailed me to let me know that the AAVSO was going to start a YSO section and forum on their website, and that he would be hosting it. I hope to be able to help him spread interest about these under-studied variable stars, and also hope to keep adding more of them to my list and making a real contribution of data about their behavior.