NOAO >   Observing Info >   Approved Programs >   2018A-0053

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Program Information for 2018A-0053


PI: Herve Bouy, University of Bordeaux, herve.bouy@u-bordeaux.fr
Address: Laboratoire d'Astrophysique de Bordeaux, Allee Geoffroy Saint Hilaire Bat 18N, Pessac, Aquitaine 33600 France

CoI: Joao Alves, Universitat Wien (University of Vienna)
CoI: Klaus Strassmeier, AIP, Germany
CoI: Michael Weber, AIP, Germany

Title: A new paradigm for star formation: understanding the nature and origin of Blue Streams

Abstract: Our understanding of star formation in the solar neighborhood has recently been turned upside down. Our analysis of the 3D spatial distribution of OB stars within 500pc from the Sun revealed large stream- like structures -- the "Blue Streams" -- covering several hundreds of parsec and about 70 Myr of continuous star formation history (Bouy & Alves, 2015). Follow-up spectroscopic observations of one of them, the Orion Blue Stream, not only allow us to confirm the existence of this structure, but also led to an even more surprising discovery: the Orion Blue Stream displays an extremely low velocity dispersion ($<$0.2km/s) over 100~pc, which cannot be explained by current models and theories of star formation. What is the origin of the blue streams? What is their role in the star formation on galactic scale? We propose to answer these pressing questions by obtaining precise radial velocity, $T_{rm eff}$ and $log~g$ measurements with the echelle spectrographs of the LCO network for all the known OB star members of the other major nearby blue stream: Sco-CMa. These measurements will have an immense legacy value, providing radial velocities an order of magnitude more accurate than Gaia for a genetically related population of massive stars covering a contiguous region of almost 350pc and 70~Myr of star formation propagation. Together with existing multi wavelength photometry (from optical to mid-IR, already at hand) and with the accurate Gaia proper motions and parallaxes (to be delivered in spring 2018, almost together with the proposed observations), these measurements will allow the construction of the most accurate star formation history of the Solar neighborhood, on spatial (350~pc) and time (70~Myr) scales never systematically probed before, and making the missing connection between star formation studies on local and extragalactic scales.

Program Type: Standard/Galactic

Scheduled Nights:
Run 1 (2018A):  LCO-1m/NRES -- 48hrs


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NOAO >   Observing Info >   Approved Programs >   2018A-0053

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