Sharpless 126 (Sh2-126) in Lacerta
September 2021 - Picture of the Month
I'm fascinated by the large scale structure of the deep-sky. Unfortunately, as a visual observer, unaided by electronics, this is something that's impossible to view directly. So enter the astrophotographer with inspiring wide-field views like this one.
Thomas has captured a feast of deep-sky objects in this 5 degree field, and the image on his website labels the main ones very nicely when you mouse-over. As you'd expect from a region like this, there are many bright nebulae, a few herbig-haro objects, a loose open cluster (ASCC 122), and even a couple of NGC galaxies.
Sharpless is catalogued as being centred in the top part of this image, right at a bright knot in LBN 437 which is full of active star formation. Its also noted to be 160 arc-minutes in extent, but as you can clearly see the nebulosity extends significantly further than that in the north-south direction; nearly 240 arc-minutes. This is large HII region of which Sharpless 126 is only a part, and its size is in part due to its proximity at about 2000 light-years.
All of this is illuminated by 10 Lacertae which is near the centre of the image and the brightest star in the area. 10 Lacertae is a massive O9V star, a suspected beta Cepheid, and an optical double with an 10th magnitude companion (S 813) about an arc-minute away. There's a 15th magnitude companion (TRN 36) at only 3.6 arc-seconds, which seems very challenging observation to me! Its nature is uncertain. Most of the bright stars here, including 10 Lacertae, are members of the Lacerta OB1 association.
It's worth mentioning that 8 Lacertae near the centre of the nebulosity has featured as one of Bob Argyle's Double Stars of the Month, back in October 2009.
James Whinfrey - Website Administrator.