The ground campaign

July 29, 2010 by

While Herschel is a wonderful instrument and delivering great results, we can’t achieve our science goals without other observations. I’m currently at Mauna Kea working on followup observations with the Sub-Millimetre Array of sources detected by Herschel. This observing run is just a small part of the large campaign of ground-based observations needed by the large Herschel surveys to find out what’s really going on in the sources we’ve detected.

For the large galaxy surveys I’m involved with among the many things we need to do are to pin down the positions of the sources seen by Herschel, so that we can find counterparts at other wavelengths, obtain spectroscopy in the optical or other bands to measure the redshifts of the sources and to determine the relative importance of star formation or black hole accretion in powering them, get higher resolution images of the sources in the submillimetre so that we can better understand the relationship between dust emission and what’s seen at other wavelengths, and get better, deeper images in the optical and near infrared so that we can see how the stars are distributed in these objects.

The observations from the SMA are steps forward on submm imaging and obtaining better positions.

Some of the antennae of the Submillimetre Array

One of the nice things about observing at the SMA is that the control room has an oxygen enriched atmosphere, so that most of the effects of altitude can be avoided. You can read more about the overall experience of an observing trip to Mauna Kea here in an article I wrote a while back for Clarkesworld magazine.

Clustering and Sky at Night

June 15, 2010 by

A couple of news items I’ve missed over the last month…

Firstly a new science result, looking at the clustering of the dusty galaxies that Herschel is detecting.

Secondly, two members of the Herschel team appeared on the BBC Sky at Night programme on 7th June. You may still be able to catch this on the BBC iPlayer.

Progress measured in meetings

June 15, 2010 by

A large international project like Herschel requires a lot of meetings so that things can be properly coordinated. I’m currently at a consortium meeting for the SPIRE instrument team. The meeting is in Padova, where the university’s astronomy department is overlooked by the observatory used by Galileo – I suspect this must be more than a little intimidating for students there! The SPIRE team is actually too big for the meeting rooms in the astronomy department so we’re meeting in the nearby department of theology, which seems to have larger and nicer facilities than the astronomers!

Apart from discussing various instrumental issues, such as calibration, pointing accuracy, performance and subsystems, we’re also getting reports from the various science teams that are using the instrument team’s guaranteed time on Herschel. It’s only about 6 weeks since the ESLAB meeting where the first Herschel science results came out, but there’s already lots of new stuff on its way. The preparations for ESLAB, and its associated science papers, was a bit frenetic. We’re now able to sit back and take a rather more measured approach to these new results. So there’ll be no new big explosion of results, but we’ll be releasing longer and rather more extensive papers in the next phase. Needless to say we’ll try to cover as many of these as possible on this blog!

Herschel and Planck win Grand Prix!

June 14, 2010 by

No, not the Monaco Grand Prix, but the Grand Prix for 2010 of the AAAF, the French Association for Aeronautics and Astronautics to acknowledge their “outstanding space endeavours”.

More information about the prize can be found from ESA and from the Planck webpages.

One year on…

May 14, 2010 by

A year ago today, Herschel and planck launched.

We’ve come a long way, and the scientific journey has only just begun!

Happy birthday Herschel and Planck!

Herschel finds a hole

May 13, 2010 by

The star forming region NGC 1999 has long puzzled astronomers because it includes a dark region where there is no emission detected in the optical or near infrared. It was thought that this indicated a region that was heavily obscured by dust. The radiation that would be emitted from this part of NGC1999 would thus be absorbed by dust which would re-readiate the energy at longer wavelengths which Herschel would be able to detected.

When Herschel astronomers observed NGC1999, though, they got a surprise…

The image shows a combination of Herschel and ground-based near infrared data on NGC1999. The important part is the region in the top left, where NGC1999 is coloured green. The hole, seen just to the right of NGC1999, is still there, dark even at Herschel wavelengths. This means there’s no dust there – it’s a hole in the nebula! The suspicion is that this is a hole blown in the material surrounding them by the stars forming in NGC1999. It’s long been known that this must occur if stars are to emerge from their nurseries, but this may be the first time they’ve been caught in the act.

For more information see the ESA discussion of these results.

And now for a gratuitous plug for….

May 8, 2010 by

my own personal (and newly transferred to) WordPress blog. Some Herschel related items, of course, but with more of an overall view of professional astronomy and the world beyond, when it rears its ugly head.

Feel free to pop over to Playing With Dust!

Press release time from the ESLAB meeting

May 6, 2010 by

ESA held a press conference a couple of hours ago to highlight some of the results from the ESLAB meeting. If you missed the live stream earlier, you can catch it here .

A number of major programs released some mouth-watering data to the general public, ranging from high resolution studies of massive star formation in our own Galaxy (the massive bubble RCW 120, which contains an embryonic massive Wolf-Rayet star, and huge star forming complexes in Aquila and Vulpecula) to studies of the high redshift universe (the H-ATLAS program).

The H-ATLAS field
Credits: ESA/ATLAS Consortium

A picture of the first field observed in the H-ATLAS survey, made by combining the images made with the SPIRE camera at 250, 350 and 500 microns. The colours in the image are not real but have been used to represent the different infrared wavelengths. The faint blue whisps at the top of the image show dust in our own Galaxy and the bright object just above the centre of the picture is a ‘Bok globule’, a dense cloud of gas and dust, also in our Galaxy, in which a small star may be forming. The other objects in the picture are all galaxies, at distances up to 12 billion light-years. The image shows that the survey is detecting objects in our celestial ‘backyard’ and also other, further ones that we are seeing as they were not long after the Big Bang.

Vulpecula
Credits: ESA/Hi-GAL Consortium

This image, in the constellation of Vulpecula, shows an entire assembly line of newborn stars. The diffuse glow reveals the widespread cold reservoir of raw material that our Galaxy has in stock for building stars.

Large-scale turbulence from the giant colliding Galactic flows causes this material to condense into the web of filaments that we see all over the image. These are the ‘pregnant’ entities where the material becomes colder and denser. At this point, gravitational forces take over and fragment these filaments into chains of stellar embryos that can finally collapse to form baby stars.

Aquila
Credits: ESA/Hi-GAL Consortium

At the centre and the left of the image, the two massive star-forming regions G29.9 and W43 are clearly visible. These mini-starbursts are forming, as we speak, hundreds and hundreds of stars of all sizes: from those similar to our Sun, to monsters several tens of times heavier than our Sun.

These newborn large stars are catastrophically disrupting their original gas embryos by kicking away their surroundings and excavating giant cavities in the Galaxy. This is clearly visible in the ‘fluffy chimney’ below W43.

The RCW 120 bubble
Credits: ESA/PACS/SPIRE/HOBYS Consortia

RCW 120 is a galactic bubble with a large surprise. How large? At least 8 times the mass of the Sun. Nestled in the shell around this large bubble is an embryonic star that looks set to turn into one of the brightest stars in the Galaxy.

The Galactic bubble is known as RCW 120. It lies about 4300 light-years away and has been formed by a star at its centre. The star is not visible at these infrared wavelengths but pushes on the surrounding dust and gas with nothing more than the power of its starlight. In the 2.5 million years the star has existed. It has raised the density of matter in the bubble wall so much that the quantity trapped there can now collapse to form new stars.

The bright knot to the right of the base of the bubble is an unexpectedly large, embryonic star, triggered into formation by the power of the central star. Herschel’s observations have shown that it already contains between 8-10 times the mass of our Sun. The star can only get bigger because it is surrounded by a cloud containing an additional 2000 solar masses.

Not all of that will fall onto the star, even the largest stars in the Galaxy do not exceed 150 solar masses. But the question of what stops the matter falling onto the star is a puzzle for modern astronomers. According to theory, stars should stop forming at about 8 solar masses. At that mass they should become so hot that they shine powerfully at ultraviolet wavelengths.

This light should push the surrounding matter away, much as the central star did to form this bubble. But clearly sometimes this mass limit is exceeded otherwise there would be no giant stars in the Galaxy. So astronomers would like to know how some stars can seem to defy physics and grow so large. Is this newly discovered stellar embryo destined to grow into a stellar monster? At the moment, nobody knows but further analysis of this Herschel image could give us invaluable clues.

The press release (which this post is based upon quite heavily!), and high-res JPEGS of these images can be found at the ESA Herschel web site.

Additional First Science press releases – which we’ll return to later – can also be found here.

Data and Data Access

May 6, 2010 by

Prompted by an exchange between myself and Brian over Twitter – always remember these are not private conversations and that the world is listening – Kevin Jardine has written an interesting post about access to scientific data over here:

http://galaxymap.org/drupal/node/165

I’ve commented there about some of the realities in large astronomy projects. Do take a look at the discussion!

The other half of ESLAB

May 6, 2010 by

While there’s a lot of stuff going on in the talks at the ESLAB Herschel meeting – and you can follow brief notes from some of us under the #eslab2010 hastag on twitter – the talks are only half of the story. A typical scientific meeting these days also has a large number of ‘poster papers’ where results are displayed in hard copy rather than as a oral presentation.

There are a huge number of poster papers here at ESLAB, covering a huge range of science and with some very exciting results, and I don’t just say this because my own paper here is a poster.

We can’t cover the content of these papers in tweets, there are just too many, but most of them will be made available by ESA once the meeting is over. I’ll try to provide a link when the web pages are up. Please take a look at them, if only to see some really astounding images from Herchel.