Tuesday, March 29, 2011

Astronomers on Twitter (who happen to be women)

On Friday I was honoured to discover that Ken Hudson, who blogs at Share Astronomy included me in a list of women astronomers (who he follows on Twitter) that he thinks are excellent role models for girls (in his post "Girls Speak Out on Physics Education").

He was motivated to make the list after watching a video on teachers.tv in which girls at a school in London are interviewed (by young women working in Physics related fields) about what they think about physics: Physics Girls Speak Out (teachers.tv)

It's an excellent and interesting video, and I encourage anyone working with young women in science to watch it.  Ken's conclusion was that the girls needed more role models - hence his list of women astronomers.

Monday, March 28, 2011

The Beauty of xkcd

I'm going to start this post by saying I'm not a regular reader of the xkcd comic strip (a humorous stick figure comic strip about science, technology and maths). 

But I have friends who love it, and post some of the hi-lights on their Facebook/Twitter streams. It was in that way that last week I stumbled across the below. Which obviously had to be posted here (click on the image to visit it on the xkcd website). 

SDSS Telescope Getting Ready to Observe (on YouTube)

In most of my research, I use data taken by the Sloan Digital Sky Survey. In the last few months I have been particularly focussed on looking at the morphologies of galaxies which are being observed as part of the ongoing Baryon Oscillation Sky Survey (or BOSS). This survey is in the process of taking spectra (to measure redshifts) of 1.5 million distant galaxies. I've just been looking at a small fraction of them which have high resolution images taken by the Hubble Space Telecope. I promise a post about that work once I submit the paper. :)

Anyway, the BOSS collaboration had a science meeting in New Mexico last week. Unfortunately I couldn't go. I phoned in to give a talk about my work, which was great, but I was still disappointed to not be physically present because the meeting included a trip to visit the actual telescope used to take all the SDSS data (both the images and spectra).

 I love telescope, particularly as the sun sets and they prepare to observe. Usually they are so peaceful and full of hope at that time of night. Who knows what they'll discover as they work hard during the darkness.

So you can imagine, I was delighted to learn that a video had been taken of the visit, and put up on YouTube. You can see lots of scientists getting in the way of the telescope operators as they prepare the telescope for a night's observing (so not as peaceful as normal!). It's all set to nice classical music, and ending with a beautiful sunset.

Watch out for the "BOSS plates" going in. These are big metal plates (a couple of metres across) which have holes drilled in them. Fibres are connected to each hole, and the plate carefully lined, so the light from a single galaxy goes down each hole. That's how SDSS can take so many spectra - hundreds are taken at once using this method.

Also watch out for the building moving off the telescope. Instead of a classic dome with an opening, or even a building with a removable roof, the SDSS telescope is covered during the day by a building which is rolled completely off the telescope at night.

To learn more about SDSS3 and BOSS you can follow the SDSS3 Blog.

Tuesday, March 22, 2011

Science Busking for Science Week

Rita Tojeiro from ICG. 
As part of Science Week festitivites at Portsmouth, I helped with Science Busking in the main local shopping street (Commercial Road) last Wednesday.

It was written about in the local paper: "Scientists Busk It". Rita hates the picture they took (right), so I hope she'll forgive me for including it. I think she looks very nice, and it shows off the lovely electric motor she made for the event. Also in the linked article I want to point out that they got the science slightly wrong -- as the person in the comments correctly says, we were pumping air out of the wine bottle to make the marshmallows expand. My job was sticking the skewer into balloons, which I then gave out to kids.

The Portsmouth University Creative and Cultural Industries Department feaured the event in their weekly news bulletin, avalailable on Vimeo:

06. CCi Live_18-03-11 from CCi Live on Vimeo.

Testing Gravity with Galaxies

A gas rich galaxy. Credit: THINGS
A few weeks ago a bunch of news articles came out suggesting that there was some new evidence that ruled out dark matter. It was all based on a paper in the journal Physical Review Letters (PRL) by Stacy McGaugh: "A Novel Test of Modified Newtonian Dynamics with Gas Rich Galaxies", which had appeared as a preprint on the arXiV, and was the subject of a press release: "Gas rich galaxies confirm prediction of modified gravity theory".

The press went a bit crazy about the paper, as was well discussed by Sean Carroll (@seanmcarroll) over at Cosmic Variance: "Dark Matter: Just Fine Thanks". He held this up as an example of the problems of communication between scientists and the science media. I think he has a point. He also presents a nice list of problems with the "alternate theory" held up in the paper: MOND (Modified Newtonian Dynamics).

Ethan Siegel has also written about the problems with the press coverage on his blog: "Good ideas, Bad ideas, MOND, and Dark Matter" illustrated very nicely with lots of pictures.

At about the same time as all this press (it was even on BBC online: Dark Matter Theory Challenged by Gassy Galaxies Result) a request to write a PRL Viewpoint on the article came across my desk.

PRL publishes Viewpoints (articles written by and for scientists) on papers they think are of note. The audience is supposed to be non-specialist physicists, so this was a fun article to write - equations allowed, but not obscure astronomical terms! I roped in my good friend Kristine Spekkens (an Assistant Professor at the Royal Military College in Canada) and we got to work.

The result appeared in PRL yesterday: "Testing Gravity in Gas Rich Galaxies", by Karen Masters and Kristine Spekkens. I was going to write a version for non-scientists for this blog, but having found the two articles by Sean Carroll ("Dark Matter: Just Fine Thanks") and Ethan Siegel ("Good ideas, Bad ideas, MOND, and Dark Matter") while looking for links to the press articles (just to be clear I only read those this morning, after writing the viewpoint) I find they've already done the job for me.

Just like them, our main conclusion is that MOND cannot compete with the standard cosmological model. It is a way of explaining the rotation curves of galaxies without dark matter, and it does that impressively well but it's not a theory of gravity, and it fails at a lot of tests that our standard gravity + dark matter + dark energy model (clunky as it is) passes with flying colours.

I think the most interesting result from McGaugh's paper is the finding that the baryon fraction scales with the rotation velocity of the galaxies (ie. is smaller for lower mass galaxies). This is presented as being an obscure fine tuning for the standard model, but actually it has the right qualitative sense (ie. there are known processes which produce something a bit like that), and can now provide a constraint to the models we have. So let me explain what it means a bit more......

Baryons are the scientific term for normal matter - atoms, electrons, protons etc. that people, stars, planets are made of. We actually have a really good measurement of what the baryon fraction averaged over the whole universe must be (compared to the radiation content). In the standard cosmological model, that fraction is set by our understanding of nuclear physics and the fractions of different light elements which are made right after the Big Bang (known as Big Bang Nucleosynthesis: wikipedia article). The baryon fraction can also be measured in CMB experiments like WMAP.

However it is well known that the baryon fraction in galaxies is lower than the cosmic average. And it makes sense that this would be so. Once the dark matter gets into a galaxy it can only be thrown out by gravity. But baryons do things. They form stars which have stellar winds, and blow up in immensly energetic supernovae. Baryons both flow into and out of dark matter halos, and the balance between those two processes depends on the mass of the halo. Massive halos have stronger gravity and so may be able to hold onto their baryons better - so they should have a higher baryon fraction, just as McGaugh's result shows.

We end our viewpoint by talking about how the next generation of radio telescopes (like SKA) will be able to make a much bigger (and more complete) sample to repeat the test McGaugh proposes. And if the result still holds, we'll have to explain it with our models of how galaxies form. But I seriously doubt it means MOND is the answer.

In fact as part of the research for this paper I also came across the following Physics World article (thanks Chaz!) which presents the best rebuttal for MOND I've seen yet: "New lower limit set for Newton's Law". At it's heart, MOND is a modification of Newton's 2nd law at low acceleration scales (not really a modification of gravity). This article presents the results of a test of Newton's 2nd Law at low acceleration scales well below where MOND proposes a change.  The only problem is that in this experiment the attractive force is the electromagnetic force rather than gravity. But that means that MOND only modifies Newton's 2nd Law for gravity, not for other forces - so that makes it an even stranger theory than it already is!

Monday, March 21, 2011

Brian Cox on Richard Feynman

I watched Brian Cox's show Wonders of the Universe last night, and following it was an advert for a BBC Radio 4 programme this afternoon with Brian Cox talking about Richard Feynman.

Given the title of my blog I hought I should link it here. It's on at 3pm today, but then also looks like it'll be on iPlayer: http://www.bbc.co.uk/programmes/b00ts5mm.

365 Days of Astronomy Podcast - Do Bars Kill Spirals?

The podcast today over at 365 Days of Astronomy is "Galaxy Zoo 2 - Do Bars Kill Spirals?" by Chris Lintott and me. We had great fun talking about the first result from Galaxy Zoo 2 - that bars are more common in redder (deader?) spirals. Hope you enjoy listening to it (should be available later today).

You can read more about that project in my Galaxy Zoo blog posts about it.

I will also be interviewd about this by Darren Gamblen of Express FM 93.7 (local Portsmouth radio) this morning at 11.30am. You can listen to the segement at this link.

Thursday, March 17, 2011

Beautiful Saturn

Just had to put this here. It's so beautiful:

Taken from one of my favourite Astronomy websites - APOD (Astronomy Picture of the Day). This is their explanation:

What would it look like to approach Saturn in a spaceship? One doesn't have to just imagine -- the Cassini spacecraft did just this in 2004, recording thousands of images along the way, and thousands more since entering orbit. Recently, some of these images have been digitally tweaked, cropped, and compiled into the above inspiring video which is part of a larger developing IMAX movie project named Outside In. In the last sequence, Saturn looms increasingly large on approach as cloudy Titan swoops below. With Saturn whirling around in the background, Cassini is next depicted flying over Mimas, with large Herschel Crater clearly visible. Saturn's majestic rings then take over the show as Cassini crosses Saturn's thin ring plane. Dark shadows of the ring appear on Saturn itself. Finally, the enigmatic ice-geyser moon Enceladus appears in the distance and then is approached just as the video clip ends.

Credit & Copyright: Cassini Imaging TeamISSJPLESANASAS. Van Vuuren et al.;
Music: Adagio for Strings (NY Philharmonic)

Monday, March 14, 2011

Beautiful Galaxies on the BBC Big Screen

As part of National Science and Engineering Week, 11-20th March 2011 in the UK I was involved in the production of a series of 5 short videos called “From the Earth to the Edge of the Universe” which were made as a collaboration between Creative Technologies and the Institute of Cosmology and Gravitation at the University of Portsmouth. They are going on the BBC Big Screens, apparently right across the UK and continuing up until the 2012 Olympics.

My segment is all about galaxy morphologies. I talk (briefly) about Galaxy Zoo and show the HST image of Hanny’s Voorwerp. I also describe some of the main morphological features of galaxies, and what I like about them.

You can watch all 5 videos here

I also blogged about this for Galaxy Zoo

Do Bars Kill Galaxies at the Royal Astronomical Society

On Friday I went up to London and spoke at the Royal Astronomical Society "Ordinary Meeting". The title of my talk was "Do Bars Kill Galaxies" - it was based on my recent Galaxy Zoo paper on the dependence of the fraction of bars on other properties of galaxies (described on the Galaxy Zoo blog in these articles).

After the meeting I met two of the Galaxy Zoo volunteers who had contributed classifications ("John F", and "Geoff"). They were very nice, and John wrote a review of the event (my talk and the other two which were given) on the Galaxy Zoo Forum.

It was a fun day out in London.

Thursday, March 10, 2011

Jocelyn Bell Burnell wins award

Jocelyn Bell Burnell at the LOFAR-UK station in Chilbolton in September 2010. Credit: James West, SEPnet.
I just posted over a the LOFAR-UK blog a story from NRAO about Jocelyn Bell Burnell winning the 2011 Grote Reber Award for lifetime contributions to radio astronomy.

Jocelyn Bell with the antennas she built and used to discover pulsars in the 1960s. Not sure of the credit for this image. 

 When I first learned the story of Jocelyn Bell Burnell discovering pulsars, as a young woman interested in astronomy she immediately became a scientific role model for me. Finally someone who looked a bit like me was in the history of astronomy. That was a really powerful moment.

 Now that I've met her on several occasions I'm happy to say I still think of her as a role model for professional science. Especially on how to act with humility and treat people with respect - and also on how to be excited about science of course. (That particularly came through I thought when I interviewed her about LOFAR in September - YouTube clip, embedded below.)

 I'm delighted every time I hear she's won another award. And I was really delighted when I learned she would be opening the LOFAR-UK station in Chilbolton. I loved the comparison we could make between the LBAs and the antennas she built in the 1960s. In some ways it looks like not much has changed in radio astronomy! Of course in other ways things are significantly different. Jocelyn Bell Burnell had to meticulously search for the signal in reams of traces made with a pen on paper. LOFAR used a massive supercomputer to combine the signal, and is only possible thanks the enormous advances in high speed internet connections and computing which have happened in the last 10 years or so.

Wednesday, March 9, 2011

Astronomy for young children - colour the solar system model.

As a mother of two young children, and an astronomer I am interested in how to present astronomy to very young children. I have some small amount of experience in this area. As a graduate student I collaborated with a 2nd grade school teacher (that's year 2, or 7 year olds) to develop a 6 week mini-course on "Understanding the Sky". The material we developed can be found here (MS Word Documentation). This experience was very educational for me in terms of what concepts young children can grasp.

A couple of weeks ago I put some of this back into practice when I visited Meon Junior School in Portsmouth (UK), and talked with two groups of 35 Year 5 students (10 year olds). They had recently been learning about the Sun and the Moon, so I decided to talk about the solar system as a way of introducing the idea of the scale of the universe.

I developed a solar system model for this visit. This was inspired by the model described here. And made heavy use of this Solar System Scale Model Calculator.

Here's the version I coloured in and cut out to use to demonstrate in the class. Just to be clear this is an accurate scale model - you can fit the Sun and all the planets on a single sheet of A4 then, cut them out and space them over a bit more than half a mile for the proper orbits. We could only fit the Sun, Mercury, Venus and (with some squeezing) the Earth in the classroom. I think that really impressed the kids.

Here's the version you can colour in yourself. 

And here are the instructions for placing the planets.  
The kids were really impressed that the nearest star would be all the way in California. 

All in all though I think the most important moment was when I was being introduced to one of the groups and a little boy said "You're not really a scientist are you?". I said "Yes, I am a scientist." It was also lovely to meet one little girl who in her free time writes reports on astronomy. She showed me her black hole report which was really impressive. 

This activity could have been done while I was there, but in the end the kids had so many great questions that I just talked to them for the whole hour (honest!). I couldn't even answer all their questions before having to leave. 

My daughter (who's 4) coloured in the planets and cut them out for herself. She demanded to have her own colouring sheet when I showed her what I was doing. We haven't yet placed the planets to scale around our house/neighbourhood, but once the weather warms up we may do that.  I may report on how well that goes. I think she's too young to understand the concept.... but we'll see.