Solving a 30-Year-Old Problem in High Mass Star Formation

This false-color Very Large Array image of the ionized gas in the star forming region Sgr B2 Main was used to detect small but significant changes in brightness of several of the sources. The blobs and filaments in this image are regions of ionized gas around massive stars. The changes in brightness detected support a model that could solve a 30-year-old question in high mass star formation. (Credit: NRAO/Agnes Scott College)

This false-color Very Large Array image of the ionized gas in the star forming region Sgr B2 Main was used to detect small but significant changes in brightness of several of the sources. The blobs and filaments in this image are regions of ionized gas around massive stars. The changes in brightness detected support a model that could solve a 30-year-old question in high mass star formation. (Credit: NRAO/Agnes Scott College)

Some 30 years ago, astronomers found that regions of ionized gas around young high mass stars remain small (under a third of a light-year) for ten times longer than they should if they were to expand as expected in simple models. Recent supercomputer simulations predicted that these regions actually flicker in brightness over this period rather than grow continuously. Observations from a team of researchers using the Jansky Very Large Array (VLA) over a 23-year period have confirmed that such flickering actually occurs. Read More →

Prawn Nebula and New Stars in High Resolution

The glowing jumble of gas clouds visible in new image make up a huge stellar nursery nicknamed the Prawn Nebula. Taken using the VLT Survey Telescope at ESO’s Paranal Observatory in Chile, this may well be the sharpest picture ever taken of this object. It shows clumps of hot new-born stars nestled in among the clouds that make up the nebula. This image also contains information from images of this object taken by Martin Pugh.

The glowing jumble of gas clouds visible in new image make up a huge stellar nursery nicknamed the Prawn Nebula. Taken using the VLT Survey Telescope at ESO’s Paranal Observatory in Chile, this may well be the sharpest picture ever taken of this object. It shows clumps of hot new-born stars nestled in among the clouds that make up the nebula. This image also contains information from images of this object taken by Martin Pugh.

A glowing jumble of clouds nicknamed the Prawn Nebula containing clumps of hot new-born stars is visible in a new, sharp image taken with the European Southern Observatory’s (ESO) VLT Survey Telescope in Chile as part of a public survey led by University of Hertfordshire astronomers. Read More →

Space ‘Scale’ to Weigh Black Holes

black-hole

A new way of measuring the mass of supermassive black holes could revolutionize our understanding of how they form and help to shape galaxies.

The technique, developed by a team including Oxford University scientists, can spot the telltale tracer of carbon monoxide within the cloud of gas (mostly hydrogen) circling a supermassive black hole at the centre of a distant galaxy. By detecting the velocity of the spinning gas they are able to ‘weigh’ (determine the mass) of the black hole.

An image of NGC 4526 showing molecular gas. Image: NASA/ESA/Tim Davies

An image of NGC 4526 showing molecular gas. Image: NASA/ESA/Tim Davies

Detailed information on supermassive black holes, thought to be at the heart of most galaxies, is scarce: it has taken 15 years to measure the mass of just 60. The problem is that most other supermassive black holes are too far away to examine properly even with the Hubble Space Telescope.

The new method, when combined with new telescopes such as ALMA (Attacama Large Millimetre/submillimetre Array), promises to extend this black hole ‘weigh-in’ to thousands of distant galaxies. It will also enable the study of black holes in spiral galaxies (similar to our own Milky Way), which are hard to target using currently available techniques.

A report of the research is published in this week’s Nature (citation below).

The team demonstrated the new technique on the supermassive black hole at the centre of a galaxy, NGC 4526, in the constellation of Virgo. NGC 4526 was chosen as a test because it has been widely studied but the team believe the technique will work on a wide range of different galaxies.

Tim Davis of the European Southern Observatory, lead author of the paper, said, “We observed carbon monoxide molecules in the galaxy we were monitoring using the Combined Array for Research in Millimetre-wave Astronomy (CARMA) telescope. With its super-sharp images we were able to zoom right into the centre of the galaxy and observe the gas whizzing around the black hole. This gas moves at a speed which is determined by the black-hole’s mass, and the distance from it. By measuring the velocity of the gas at each position, we can measure the mass of the black hole.”

Dr Michele Cappellari of Oxford University’s Department of Physics, an author of the paper, said, “Because of the limitations of existing telescopes and techniques we had run out of galaxies with supermassive black holes to observe. Now with this new technique and telescopes like ALMA we will be able to examine the relationship between thousands of more distant galaxies and their black holes giving us an insight into how galaxies and black holes co-evolve. Importantly our ‘weigh-in’ technique will work for all kinds of galaxies, including spiral galaxies which are particularly difficult to observe with previous techniques.”

Dr Martin Bureau of Oxford University’s Department of Physics, an author of the paper, said: “The ALMA telescope is now in the final stages of construction and our team is currently bidding for time to use it for our black hole survey. If all goes according to plan we could begin our survey by the end of this year.”

Source: University of Oxford

Reference:

Davis, T., Bureau, M., Cappellari, M., Sarzi, M., & Blitz, L. (2013). A black-hole mass measurement from molecular gas kinematics in NGC4526 Nature DOI: 10.1038/nature11819

Hubble’s Panoramic View of a Turbulent Star-making Region

30 Doradus is the brightest star-forming region in our galactic neighborhood and home to the most massive stars ever seen. The nebula resides 170 000 light-years away in the Large Magellanic Cloud, a small, satellite galaxy of our Milky Way. No known star-forming region in our galaxy is as large or as prolific as 30 Doradus. Read More →

Workings of Nearby Planetary System Revealed

A new observatory still under construction has given astronomers a major breakthrough in understanding a nearby planetary system and provided valuable clues about how such systems form and evolve. Astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) have discovered that planets orbiting the star Fomalhaut must be much smaller than originally thought. This is the first published science result from ALMA in its first period of open observations for astronomers worldwide. Read More →

Sandstorms in Space

A team of researchers have used new techniques which allowed them to look into the atmospheres of distant, dying stars.

The team, lead by Barnaby Norris from the University of Sydney in Australia, includes scientists from the Universities of Manchester, Paris-Diderot, Oxford and Macquarie University, New South Wales. They used the Very Large Telescope in Chile, operated by the European Southern Observatory. Read More →