One question raised in the thread in the Lounge is whether it is possible to identify the spiral structure of the Milky Way from the Gaia dataset. I have tried to do this by marking the OB stars: massive, short-lived stars that do not live long enough to move very far from their birthplaces, which should be concentrated in the spiral arms. With the dataset as it stands, this is not possible due to a large number of stars that are misidentified as OB-stars based on their B-V colour index. I am working on further updates to the dataset that may help correct this.
Watch this space!
About two years ago I did quite a lot of research work to infer the MW spiral structure and extent from new kinds of data.
The point was to combine the new data on Massive Young Stellar Objects (MYSOs
) and compact / ultra-compact HII regions with a complete set of published ATNF pulsar data
, which largely increases the evidence for the arm structure from the RMS
= Red MSX Source data alone.
I actually communicated several times with the RMS lead scientist Prof. J.S. Urquhart,
who was so kind as to also send me their "hot" numerical data! Chris (ElChristou) helped actively on the graphical side.
(published in MNRAS 437, 1791–1807 (2014), linkhttp://mnras.oxfordjournals.org/content ... l.pdf+htmlhttp://www.ast.leeds.ac.uk/RMS/http://www.sci-news.com/astronomy/scien ... 01649.html
The RMS reference about MYSOs and compact / ultra-compact HII regions represents the cleanest recent evidence for a four principal arm structure of the MW
(Norma, Sagittarius, Perseus and Scutum-Centaurus arms). Moreover, it provides lots of data tracing the so-called Outer arm in the region of present interest (II nd quadrant) (You remember that the Spitzer telescope claimed in 2008 to see only 2 principal arms...)
Here is a summary image from the above RMS paper:[click on image by all means for a much bigger size!]
rms_MW.jpg [ 102.47 KiB | Viewed 482 times ]
Soon more details...
Watch this space...
The MW template in celestia.Sci
takes these new astronomical measurements into account!