mollwollfumble said:
Esa space telescope hipparcos has been dead for a while now but a recent 3_D analysis of its data has found some strange results. (Darn, haven’t figured cut and paste on tablet yet). See sci.esa.int/hipparcos
In a study of hot o and b stars, the Gould belt doesn’t exist. Instead, there’s a very long stream of stars that reaches from the Orion nebula 1300 ly away to the other Orion stars 250 to 800 ly away.
There are also two other equally large star streams. One from Scorpio to canus major, the other in vela. Because these stars are so bright they also have very short lifespans, so are very young, typically 65 million years old or less.
http://sci.esa.int/hipparcos/56834-another-dimension-3d-visualisation-redefines-milky-ways-local-architecture/
Astronomers have used modern techniques to visualise data from ESA’s Hipparcos space astrometry mission in three dimensions. The treatment of the data has offered insights into the distribution of nearby stars and uncovered new groupings of stars in the solar neighbourhood, shedding light on the origins of the stars in Orion and calling into question the existence of the Gould Belt – an iconic ring-shaped structure of stars in the Milky Way. The results show the potential of 3D visualisation of the solar neighbourhood, an approach which is of particular relevance to ESA’s Gaia mission which will map the Milky Way and Local Group in 3D with unprecedented sensitivity and accuracy.
The team found that the solar neighbourhood is dominated by three huge stream-like galactic structures made up of dense clusters and loose associations of young, blue, O and B type stars. These contain several tens of O and B type stars, most of the local well-known clusters, and some previously unreported stellar groups. The first structure runs from the constellation Scorpius to the constellation Canis Majoris covering more than 1100 light years and at least 65 million years of star formation history. The second, located in the constellation Vela, covers at least 500 light years and 30 million years of history. Although all three of the newly discovered streams have a story to tell, it is the third structure, located in the constellation Orion, that is perhaps the most significant due to its mystery-solving qualities.
The origin of the blue supergiants that define the body and belt of the Orion constellation has long been a mystery. The five giant O and B type stars are located between around 250 and 800 light years from Earth and as a result it was assumed that their origin was not, despite their name, in the prolific Orion Nebula star-forming region, which lies around 1300 light years from Earth. However, the discovery of the Orion stream offers a simple solution. It implies that these relatively distant populations are in fact linked as part of a large galactic structure, which spans more than 1000 light years and at least 25 million years of star formation history.