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YSO Bulletin
- January 2021 -

- Don't forget Orion! -

The Campaign

We are now at the end of the observational campaign, run in association with the Hubble Space Telescope (HST) to study pre-main-sequence stars in two areas of Orion - of which there are several, not just the M42 region! The full list of stars was published in last month's newsletter, where it was also stated that there is to be a subsequent campaign with the HST, but for young stars in southern-hemisphere starforming regions. As yet we have had no details about this but rest assured that when we do, everyone will be kept informed, both by an alert notice from HQ but also of course via these newsletters.

False Friends

The article to the right about the Pelican Nebula reminds me of a little something to be wary of - what are called in the field of languages 'false friends' - words in another language that look as though they mean something similar in your own tongue, but don't! There are some parallel examples in the sky - just because you have a variable star in the middle of a starforming region doesn't automatically mean it's a YSO! An example of this is V751 Cygni, actually shown in the photo here. Because of its position and variability it was long assumed to be a YSO but in fact it is a VY Scl object, thus a type of CV.
Likewise, there are two variables close to the actual YSO UX Ori that I marked down as possible stars of the same type when I ran the 'hidden UXORs' campaign at AAVSO, because they were apparent Algol stars but near a starforming region SW of M42. In the past such stars have often been listed as algols but were UXORs. Well - it turns out that these two stars, EQ and FL Ori, are algols!

Cygnus Study

There has recently been a spectroscopic survey of the starforming region near ξ Cyg which of course means the North America and Pelican nebulae (NAP) which, apart from being highly photogenic, are major starforming regions.
click for bigger (and original) image
All images: Shaun Reynolds

580 young stars were identified as likely members of the NAP region based on criteria involving infrared excess, Lithium absorption, X-ray emission, parallax, and proper motions. The measured ages of stellar kinematic groups, combined with inferred ages for embedded stellar populations revealed by Spitzer, suggests a sequential history of star formation in the NAP region.