Starship Asterisk*

Only 450 light years away? That's closer than the star Betelgeuse. And farthest away 1,500 light years. The star in Orion's belt, Alnilam is 1,340 ly away. [Wikipedia's Orion Belt article. When clicking on Alnilam's main article, it says Alnilam is 2,000 ly away.] So basically if we change the Gum's 450 light years to 600 ly of Betelgeuse, the Gum Nebula would fit into the space between Betelgeuse and Alnilam in the constellation Orion.

[url]https://www.google.ca/search?q=does+your+chewing+gum+lose+its+flavour+on+the+bedpost+overnight&rlz=1C1CHZL_enCA751CA791&oq=does+your+chewing+gum+lose+its+flavour+on+the+bedpost+overnight&aqs=chrome..69i57.9591j0j4&sourceid=chrome&ie=UTF-8[/url]

[quote=" https://www.aanda.org/articles/aa/full_html/2017/06/aa30867-17/aa30867-17.html"]

[b][size=150][color=#0000FF]Multiple kinematical populations in Vela OB2 from Gaia DR1 data[/color][/size][/b]
F. Damiani1, L. Prisinzano1, R. D. Jeffries2, G. G. Sacco3, S. Randich3 and G. Micela1

<<The Vela OB2 association spans a wide sky region inside the Gum nebula (Pettersson 2008) and has been subject to an increasing number of studies in recent years..., as we describe below, the Gaia proper-motion data show clear evidence of a double population in Vela OB2, with intriguing analogies with those from the Gaia-ESO survey data.

Using their well-defined mean proper motions, we may trace back in time the apparent average positions of populations C and D over a few Myr.The arrows in [url=https://www.aanda.org/articles/aa/full_html/2017/06/aa30867-17/F4.html]Fig. 4[/url] show the positions of [url=https://en.wikipedia.org/wiki/Gamma_Velorum]γ[sup]2[/sup] Vel[/url] and [url=https://en.wikipedia.org/wiki/NGC_2547]NGC 2547[/url] extrapolated back 1.1 Myr, using the(error-weighted) mean proper motions of concentrated populations C and D.This shows that their (sky-projected) distance is now slowly increasing,while it reached a minimum value of 0.65 degrees (4.04 pc) 1.1 Myr ago. This is a small enough value, compared to the apparent sizes of both γ[sup]2[/sup] Vel and NGC 2547 clusters, to expect a significant dynamical interaction between them, provided that also their distances from the Sun are (or were at that time) coincident within a few pc. An intriguing possibility is therefore that population B in the γ[sup]2[/sup] Vel cluster originates from a tidal stripping event during a close encounter with the (denser) cluster NGC 2547. One difficulty with this hypothesis lies in the offset of the RV distribution of population B with respect to that of population A, whereas tidal stripping may be expected to create two symmetric (leading and trailing) tails.

To summarise, the Gaia DR1 data indicate that populations C and D had the highest probability of a mutual interaction in the past 1−1.5 Myr. Determining if this has actually taken place depends on a more accurate determination of the populations’ respective parallaxes, which are expected from future Gaia data releases. [b][u][color=#0000FF]Future Gaia data releases will permit a more accurate determination of its properties.[/color][/u][/b]>>[/quote][float=right][img3=""]http://img.sharetv.com/shows/standard/alf.jpg[/img3][/float][youtube]https://www.youtube.com/watch?v=H0eqzzcvisw[/youtube]

Exquisite.
Wonderfully planned and executed and the processing is spot on.
Well done, John.

dan kowall

[url=https://apod.nasa.gov/apod/ap180524.html] [img]https://apod.nasa.gov/apod/calendar/S_180524.jpg[/img] [size=150]The Gum Nebula Expanse[/size][/url]

[b] Explanation: [/b] Named for a cosmic cloud hunter, Australian astronomer [url=http://galaxymap.org/drupal/node/33]Colin Stanley Gum[/url] (1924-1960), [url=http://galaxymap.org/drupal/node/74]The Gum Nebula[/url] is so large and close it is actually hard to see. [url=https://apod.nasa.gov/apod/ap020217.html]In fact[/url], we are only about 450 light-years from the front edge and 1,500 light-years from the back edge of this interstellar expanse of glowing hydrogen gas. Covered in [url=https://www.astrobin.com/346877/0/]this 40+ degree-wide[/url] monochrome mosaic of [url=https://apod.nasa.gov/apod/ap051223.html]Hydrogen-alpha[/url] images, the faint emission region stands out against the background of Milky Way stars. The [url=http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1993A%26A...280..231S]complex[/url] nebula is thought to be a [url=http://chandra.harvard.edu/xray_sources/supernovas.html]supernova remnant[/url] over a million years old, sprawling [url=https://en.wikipedia.org/wiki/Argo_Navis]across the Ship's[/url] southern constellations Vela and Puppis. This spectacular wide field view [url=https://apod.nasa.gov/apod/image/0908/Vela_50mm_HaRGB_f88l.jpg]also explores[/url] many objects embedded in The Gum Nebula, including the younger [url=https://apod.nasa.gov/apod/ap080306.html]Vela supernova remnant[/url].


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