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First look at gravitational dance that drives stellar formation

Last Updated on Thursday, 06 July 2017 08:55
Published on Wednesday, 05 July 2017 23:01

Swirling motions in clouds of cold, dense gas have given, for the first time, an active insight into how gravity creates the compact cores from which stars form in the interstellar medium. The results will be presented today, Thursday 6 July, by Gwen Williams at the National Astronomy Meeting at the University of Hull.

movie1 sdc13Animation showing exactly how the dense ammonia gas moves within the SDC13 filament network. Credit: G. Williams et al. / University of Cardiff. Click for a larger image

 

Williams, of Cardiff University, explains: “We’ve known for some time that dusty, filamentary cloud structures are ubiquitous in the Milky Way’s interstellar medium. We also know that the densest of these filaments fragment into compact pockets of cold gas that then collapse under their own gravity to form individual stars. However, there’s still been a question mark over how, exactly, this happens.”

 

SDC13 is a remarkable cloud network of four filaments converging on a central hub, with a total mass of gas equivalent to a thousand of our Suns. Observations by Williams and colleagues at Cardiff University and the University of Manchester, using the Jansky Very Large Array (JVLA) and the Green Bank Telescope (GBT), have now captured the effects of gravity on ammonia gas moving within the SDC13 system.

 

Material is pulled from surrounding filaments and accreted onto cores dotted along the cloud structure, converting gravitational potential energy into kinetic energy in the process. Intense surges in the gas motion are observed at two-thirds of the cores that have yet to form stars.

 

Williams notes: “We believe that the same processes are at work at the filament junction, where both the largest internal motions of the gas and the most massive cores are found. We also speculate that strong acceleration gradients are generated at the hub centre resulting in large accumulation of matter and the formation of massive cores. Hence, our results reveal that this type of interstellar filament and hub system represents a privileged location for the formation of the most massive of stars in the Galaxy.”

  


Media contacts

 

NAM press office (Monday 3 – Thursday 6 July)

Tel: +44 (0)1482 467507 / (0)1482 467508

 

Robert Massey

Royal Astronomical Society

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Anita Heward

Royal Astronomical Society

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Morgan Hollis

Royal Astronomical Society

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Science contacts

 

Gwen Williams

University of Cardiff

Mob:  44(0)7805 954496

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Nicolas Peretto

University of Cardiff

Tel: +44(0)2920 874649

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Images and captions

 

Left: three colour composite image of SDC13 where red, green and blue bands correspond to 70μm HIGAL (Molinari et al. 2010), 24μm Spitzer MIPSGAL (Carey et al. 2009) and 8μm Spitzer GLIMPSE (Churchwell et al. 2009) maps respectively. The four dark, filamentary arms are clearly visible. Right: Brand new, high resolution map of SDC13 tracing the internal dense Ammonia gas revealing cores dotted along all the filaments. Credit: G. Williams et al. / University of Cardiff

 

Map of the average internal motions of the dense gas (termed velocity width) for all cores that showed a peak in the velocity width. The overlaid contours represent the average density of the dense gas. Credit: G. Williams et al. / University of Cardiff

 

Animation showing exactly how the dense ammonia gas moves within the SDC13 filament network. Credit: G. Williams et al. / University of Cardiff

 


Notes for editors

 

Running from 2 to 6 July, the RAS National Astronomy Meeting 2017 (NAM 2017, http://nam2017.org) takes place this year at the University of Hull. NAM 2017 will bring together around 500 space scientists and astronomers to discuss the latest research in their respective fields. The conference is principally sponsored by the Royal Astronomical Society and the Science and Technology Facilities Council.

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The Royal Astronomical Society (RAS, www.ras.org.uk), founded in 1820, encourages and promotes the study of astronomy, solar-system science, geophysics and closely related branches of science. The RAS organises scientific meetings, publishes international research and review journals, recognizes outstanding achievements by the award of medals and prizes, maintains an extensive library, supports education through grants and outreach activities and represents UK astronomy nationally and internationally. Its more than 4000 members (Fellows), a third based overseas, include scientific researchers in universities, observatories and laboratories as well as historians of astronomy and others.

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The Science and Technology Facilities Council (STFC, www.stfc.ac.uk) is keeping the UK at the forefront of international science and has a broad science portfolio and works with the academic and industrial communities to share its expertise in materials science, space and ground-based astronomy technologies, laser science, microelectronics, wafer scale manufacturing, particle and nuclear physics, alternative energy production, radio communications and radar.

STFC's Astronomy and Space Science programme provides support for a wide range of facilities, research groups and individuals in order to investigate some of the highest priority questions in astrophysics, cosmology and solar system science. STFC's astronomy and space science programme is delivered through grant funding for research activities, and also through support of technical activities at STFC's UK Astronomy Technology Centre and RAL Space at the Rutherford Appleton Laboratory. STFC also supports UK astronomy through the international European Southern Observatory. 

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