Weltevreden SA
25-11-2017, 10:31 AM
Hi all, I've been quiet for awhile over here in S Africa because I'm part of the crew starting up a free online magazine for Southern sky observers, called Nightfall (assa.saao.ac.za/sections/deep-sky/nightfall/).
Here is an example of what we are doing from the first issue:
We occasionally hear about "O runaways" — giant, furiously hot Class-O stars that are unaccountably speeding along in near-solitude in parts of the Galaxy where they shouldn’t be. They are easy to find, bright even in a pair of binoculars.*They tell a tale about stellar life styles within galaxies that we could discover no other way. While the usual web searches turn up plenty of technical articles about O stars that reside in star clusters, but not much useful observing data about O runaways. For one: what are they running from? And why?
Now the Astro.Society of S Africa's free online magazine "Nightfall" has produced a comprehensive and free 27-page Observer's Guide (assa.saao.ac.za/wp-content/uploads/sites/23/2017/11/NF_v2n1_Supplement_O_runaway_stars. pdf) anyone can download and use for free. It starts with an 18-page account about O star origins, lives, and fates, followed by a 9-page table listing the 46 brightest O runaways visible with the unaided eye or with small binoculars. There are hundreds of embedded web links to guide you to images and further info.
*
Since Orion is now rising, you can begin logging the 46 by tracking down AE Aurigae and Mu Columbae. These two started as a mid-mass binary in a hot young star cluster in the Orion B Association. Early in life, AE Aug and Mu Col ventured too close to the very massive O "bully binary" (every young cluster has one) in the cluster core. In the resulting tangle of the giants, AE Aug and Mu Col were split apart as a binary and flung hundreds of light years in opposite directions. They are easy to find, but you'd never guess from their huge separation today that they started out as a tight binary near the central belt star Alnilam in Orion.
*
Indeed all O runaways got their start as a single star or binary that tangled with a bully binary. How they got to be where they are today is the same tale told 46 different ways. The full story is here (assa.saao.ac.za/wp-content/uploads/sites/23/2017/11/NF_v2n1_Supplement_O_runaway_stars. pdf) as an 16.78 MB PDF download.*
=Dana in S Africa
Here is an example of what we are doing from the first issue:
We occasionally hear about "O runaways" — giant, furiously hot Class-O stars that are unaccountably speeding along in near-solitude in parts of the Galaxy where they shouldn’t be. They are easy to find, bright even in a pair of binoculars.*They tell a tale about stellar life styles within galaxies that we could discover no other way. While the usual web searches turn up plenty of technical articles about O stars that reside in star clusters, but not much useful observing data about O runaways. For one: what are they running from? And why?
Now the Astro.Society of S Africa's free online magazine "Nightfall" has produced a comprehensive and free 27-page Observer's Guide (assa.saao.ac.za/wp-content/uploads/sites/23/2017/11/NF_v2n1_Supplement_O_runaway_stars. pdf) anyone can download and use for free. It starts with an 18-page account about O star origins, lives, and fates, followed by a 9-page table listing the 46 brightest O runaways visible with the unaided eye or with small binoculars. There are hundreds of embedded web links to guide you to images and further info.
*
Since Orion is now rising, you can begin logging the 46 by tracking down AE Aurigae and Mu Columbae. These two started as a mid-mass binary in a hot young star cluster in the Orion B Association. Early in life, AE Aug and Mu Col ventured too close to the very massive O "bully binary" (every young cluster has one) in the cluster core. In the resulting tangle of the giants, AE Aug and Mu Col were split apart as a binary and flung hundreds of light years in opposite directions. They are easy to find, but you'd never guess from their huge separation today that they started out as a tight binary near the central belt star Alnilam in Orion.
*
Indeed all O runaways got their start as a single star or binary that tangled with a bully binary. How they got to be where they are today is the same tale told 46 different ways. The full story is here (assa.saao.ac.za/wp-content/uploads/sites/23/2017/11/NF_v2n1_Supplement_O_runaway_stars. pdf) as an 16.78 MB PDF download.*
=Dana in S Africa