Sunday, July 26, 2015

Journey to the edge of a forming galaxy

in early july i spent two weeks as "scientist in residence" at the ABC as a result of the Top 5 Under 40 award.  the main project i worked on was producing a science ninja adventure story that went live on the science show on radio national yesterday afternoon!

journey to the edge of a forming galaxy (website)
journey to the edge of a forming galaxy (mp3)

Artwork by Mischa Andrews from photo by Jenny Gabache and galaxy image by David Malin

long time readers may remember the seeds of this story from a blog post in 2010. you never know what direction random inspiration will go!

transforming the written story into something radio-ready was an interesting challenge.  phrases that look lovely on the page do not sound smooth or conversational when spoken out loud.  i wrote many versions of the story (in less than 2 days) before settling into one that i could read out loud comfortably.

Artwork by Glen Nagle

once the story was ready, i had the amazing luck of booking an entire afternoon in the studio with award-winning sound engineer Russell Stapleton.  i had shared an early draft of the story with him and he came prepared with directories of "space and ninja" sounds that he had been working with for the last 20 years!  he really made the story come alive and it was fascinating to watch him work. such a unique experience to work with him to create the depth of sound you hear throughout the story.

the science show producer asked me for some unique artwork to display with the story on the webpage, since a regular galaxy image would be a bit boring.  i was busy at a workshop during the couple days i had to produce the image, so i asked twitter for volunteers to help.  they certainly came through - the images are displayed through this post.  thanks so much to Mischa Andrews and Glen Nagle!

Put together by Glen Nagle from photo by Jenny Gabache and galaxy image by David Malin

Hope you enjoy the adventure!

Sunday, July 19, 2015

2015 David Malin Award Winners

Here is the first batch of winning astrophotos from the annual David Malin Awards contest.  These are absolutely stunning captures from non-professional astronomers around australia!

Overall Winner: "Stellar Riches" by Troy Casswell

Deep sky winner: "The Fighting Dragons of Ara" by Andrew Campbell

Nightscape winner: "Aurora Treescape" by James Garlick

Solar system winner: "Solar Crown" by Peter Ward

Saturday, July 18, 2015

seeing the universe through spectroscopic eyes

I published this article at The Conversation last week, reproduced here for your enjoyment :) Original article link

Seeing the Universe Through Spectroscopic Eyes

When you look up on a clear night and see stars, what are you really looking at? A twinkling pinprick of light with a hint of colour?

Imagine looking at a starry sky with eyes like prisms that separate the light from each star into its full rainbow of colour. Astronomers have built instruments to do just that, and spectroscopy is one of the most powerful tools in the astronomer’s box.

The technique might not produce the well-known pretty pictures sent down by the Hubble Space Telescope, but for astronomers, a spectrum is worth a thousand pictures.

Visible spectra reveal huge amounts of information about objects in the distant cosmos that we can’t learn any other way.

So what is spectroscopy?

Spectroscopy is the process of separating starlight into its constituent wavelengths, like a prism turning sunlight into a rainbow. The familiar colours of the rainbow correspond to different wavelengths of visible light.

The human eye is sensitive to the visible spectrum – a narrow range of frequencies among the entire electromagnetic spectrum. The visible spectrum covers wavelengths of roughly 390 nanometers to 780 nanometers (astronomers often use units of Angstroms (10-10), so visible light spans 3,900 to 7,800 Angstroms).

Once visible starlight reaches the curved primary mirror of a telescope, it is reflected toward the focal point and can then be directed anywhere. If the light is sent directly to a camera, an image of the night sky is seen on a computer screen as a result.

If the light is instead sent through a spectrograph before it hits the camera, then the light from the astronomical object gets separated into its basic parts.

A very simple spectrograph was used by Issac Newton in the 1660s when he dispersed light with a glass prism. Modern spectrographs consist of a series of optics, a dispersing element and a camera at the end. The light is digitised and sent to a computer, which astronomers use to inspect and analyse the resulting spectra.

The video (above) shows the path of distant starlight through the 4-metre Anglo-Australian Telescope (AAT) and a typical spectrograph, revealing real data at the end.

What do spectra teach us?

A spectrum allows astronomers to determine many things about the object being viewed, such as how far away it is, its chemical makeup, age, formation history, temperature and more. While every astronomical object has a unique rainbow fingerprint, some general properties are universal.

Top shows a spiral galaxy spectrum. Bottom shows non-star-forming galaxy spectrum.
Screenshot from Australian Astronomical Observatory video above

Here we examine the galaxy spectra shown in the video. The spectrum of a galaxy is the combined light from its billions of stars and all other radiating matter in the galaxy, such as gas and dust.

In the top spectrum you can see a few strong spikes. These are called “emission lines” and occur at discrete wavelengths due to the atomic structure of atoms as electrons jump between energy levels.

The hydrogen spectrum is particularly important because 90% of the normal matter in the universe is hydrogen. Because of the details of hydrogen’s atomic structure, we recognise the strong hydrogen-alpha emission line at roughly 7,500 Angstroms in the top spectrum image.

In a galaxy, only the youngest, biggest stars are hot enough to excite surrounding hydrogen gas enough that the electrons populate the third energy level, before falling to the second lowest, thus emitting a hydrogen-alpha photon.

Because of this, we know the strength of the hydrogen-alpha line in a galaxy’s spectrum indicates how many very young stars there are in the galaxy. Since the bottom spectrum shows no hydrogen-alpha emission, we can conclude that the bottom galaxy is not sparking new life in the form of shining stars, while the top galaxy harbours several hard working stellar nurseries.

In the bottom spectrum you can see a number dips. These are called “absorption lines” because they appear in the spectrum if there is anything between the light’s source and the observer on Earth absorbing the light. Absorbing material could be the extended layers of a star or interstellar clouds of gas or dust.

The absorption lines close to each other below 5,000 Angstroms in the bottom spectrum are the calcium H and K lines and can be used to determine how quickly stars are zooming around the galaxy.

In a galaxy how far away?

A basic piece of information derived from a spectrum is the distance to the galaxy, or specifically, how much the light has stretched during its journey to Earth. Because the universe is expanding, the light emitted by the galaxy is stretched toward redder wavelengths as it innocently moves across space. We measure this as redshift.

To determine the exact distance of a galaxy, astronomers measure the well-studied pattern of absorption and emission lines in the observed spectrum and compare it to the laboratory wavelengths of these features on Earth. The difference tells how much the light was stretched, and therefore how long the light was travelling through space, and consequently how far away the galaxy is.

The absorption lines ‘shift’ the farther away an object is, giving us an indication of its distance from us.
Georg Wiora (Dr. Schorsch)

In the top galaxy spectrum mentioned earlier, we measure the strong red emission line of hydrogen-alpha to be at a wavelength of roughly 7,450 Angstroms. Since we know that line has a rest wavelength of 6,563 Angstroms, we calculate a redshift of 0.13, which means the light was travelling for 1.7 billion years before it reached our lucky telescope. The galaxy emitted that light when the universe was roughly 11.8 billion years old.

Australia’s strength in spectroscopy

Australia has led the way internationally for spectroscopic technology development for the last 20 years, largely due to the use of fibre optics to direct galaxy light from the telescope structure to the spectrograph.

A huge advantage of using optical fibres is that more than one spectrum can be obtained simultaneously, drastically improving the efficiency of the telescope observing time.

Australian astronomers have also led the world in building robotic technologies to position the individual optical fibres. With these, the AAT and the UK Schmidt Telescopes (both located at Siding Spring Observatory in New South Wales) have collected spectra for a third of all the 2.5 million galaxy spectra that humans have ever observed.

While my own research uses hundreds of thousands of galaxy spectra for individual projects, it still amazes me think that each one of these spectra are composite collections of light created by hundreds of billions of stars gravitationally bound together in a single swirling galaxy, many similar to our own Milky Way home.

Tuesday, July 14, 2015

discovering pluto

later today, the new horizons space craft will fly by pluto at a distance of only 12,500 km - its closest approach is about 1 earth away.   that's incredible!

this mission has already given us way better views of the dwarf planet than we've ever achieved (even with hubble).  what will the new data tell us?  what does the surface looks like? (are there craters? ice? cracks? plumes? mountains?)  what is the atmosphere is made of? (methane, nitrogen, and what else?) does its surface ice turn to gas during different seasons and then does it get released to space?

ultimately, we want to understand what the objects way out in the kuiper belt are made of because they can tell us how all the other planets and the entire solar system was formed.

Created by Alex Parker with NEW images of pluto!
new horizons cannot send data back at the same time it is taking images, so it is following an automatic program, written by the engineers and astronomers, to maximize its data collection during the flyby.  we will receive the first message and prelim images tomorrow (july 15th, 2015 - it takes 4.5 hours for the data to reach earth).  cant wait!

then new horizons will start sending data back to us over the next ~16 months as it flies away out into the depths of the kuiper belt at the outskirts of our solar system.

i'm excited.

i talked (enthusiastically) to Patricia Karvelas on radio national's drive program last friday about pluto and what to expect from this flyby. you can LISTEN HERE.

it also seems like the perfect time to break out this old number: pluto, the previous planet :)

Pluto, the previous planet from carolune on Vimeo.

Sunday, June 28, 2015

kalaya - beautiful australian night sky timelapse

the australian night sky never disappoints, especially when viewed from far out into the outback.  a talented australian astrophotographer, greg priestley, was able to capture the milky way and the "emu" rising above uluru and kata tjuta in may 2014.

kalaya is the aboriginal word for emu.

beautiful work!

Kalaya - David Malin Awards from Greg Priestley on Vimeo.

Tuesday, June 23, 2015

dirty space news update

here are a few pieces of dirty space news that i've collected recently, all together in one happy place for your enjoyment.

from a paper simulating magnetic fields called "High Energy Neutrino Emission from Astrophysical Jets in the Galaxy."  i particularly like the last line of the abstract: "One of the main ingredients of the present work is the presence of a toroidal magnetic field that confines the jet flow and furthermore greatly affects the distribution of the high energy neutrinos." 
Caption from paper: A plot of the magnetic field magnitude roughly half way into the simulation. We can see the jet self-confinement due to magnetic forces resulting in a narrow beam.

Adrian Price-Whelan on twitter shared a graph he created for his research and wondered "maybe it's not that bad, just my inner 11 year old showing." i think we can all agree that it is that bad.  

helpfully, a fellow astronomer suggested that "if you switched x and y, it might not be quite so snigger-worthy." i'm not sure it helped... 

and finally, yet another space vehicle for our dirty space news entertainment - Blue Origin's New Shepard space vehicle completed its first developmental test flight.

there is even a viedo of the launch!

Monday, June 22, 2015

planetary pair: venus & jupiter approaching!

venus is incredibly bright in the evening sky right now, and if you get out and LOOK UP, you won't miss the other bright object right by it - the planet jupiter!  they will keep getting closer and closer to each other over the next week and a half, culminating in what will appear to be a very bright double star system on july 1st.

it's quite a beautiful sight - make sure you enjoy it!  read more by tanya munro at the conversation.

here was the view from Brno, Czech Republic as photographed by Pavel Gabzdyl.

Photo by Pavel Gabzdyl

the view it turned around from the southern hemisphere!  this shot was taken by chris wyatt in australia.
Photo by chris wyatt

Wednesday, May 27, 2015

Galaxy’s snacking habits revealed

an unexpected part of my position as "outreach officer" has been inheriting the role of "press officer" for the Australian Astronomical Observatory (AAO).  this isnt something i want to spend too much time on, but i do enjoy the occasional challenge of turning technical science results into fun stories accessible to media sources and a more general audience.

for this joint release, i received help and advice from a very experienced science communicator and press officer in western australia, pete wheeler.  much appreciated! i've learned a lot about the process of putting together the best material and advertising it properly to international media, as these are not things i've learned in my normal scientific training.

but definitely my favourite part has been the writing of the story to go with work led by AAO astronomer Ángel López-Sánchez.  so here you go - new science!

Multiwavelength image of the galaxies NGC 1512 and NGC 1510 combining optical and near-infrared data (light blue, yellow, orange), ultraviolet data (dark blue), mid-infrared data (red), and radio data (green). 

Galaxy’s snacking habits revealed

A team of Australian and Spanish astronomers have caught a greedy galaxy gobbling on its neighbours and leaving crumbs of evidence about its dietary past.

Galaxies grow by churning loose gas from their surroundings into new stars, or by swallowing neighbouring galaxies whole. However, they normally leave very few traces of their cannibalistic habits.

A study published today in Monthly Notices of the Royal Astronomical Society (MNRAS) not only reveals a spiral galaxy devouring a nearby compact dwarf galaxy, but shows evidence of its past galactic snacks in unprecedented detail.

Australian Astronomical Observatory (AAO) and Macquarie University astrophysicist, Ángel R. López-Sánchez, and his collaborators have been studying the galaxy NGC 1512 to see if its chemical story matches its physical appearance.

The team of researchers used the unique capabilities of the 3.9-metre Anglo-Australian Telescope (AAT), near Coonabarabran, New South Wales, to measure the level of chemical enrichment in the gas across the entire face of NGC 1512.

Chemical enrichment occurs when stars churn the hydrogen and helium from the Big Bang into heavier elements through nuclear reactions at their cores. These new elements are released back into space when the stars die, enriching the surrounding gas with chemicals like oxygen, which the team measured.

“We were expecting to find fresh gas or gas enriched at the same level as that of the galaxy being consumed, but were surprised to find the gases were actually the remnants of galaxies swallowed earlier,” Dr López-Sánchez said.

“The diffuse gas in the outer regions of NGC 1512 is not the pristine gas created in the Big Bang but is gas that has already been processed by previous generations of stars.”

CSIRO's Australia Telescope Compact Array, a powerful 6-km diameter radio interferometer located in eastern Australia, was used to detect large amounts of cold hydrogen gas that extends way beyond the stellar disk of the spiral galaxy NGC 1512.

"The dense pockets of hydrogen gas in the outer disk of NGC 1512 accurately pin-point regions of active star formation", said CSIRO's Dr Baerbel Koribalski, a member of the research collaboration.

When this finding was examined in combination with radio and ultraviolet observations the scientists concluded that the rich gas being processed into new stars did not come from the inner regions of the galaxy either. Instead, the gas was likely absorbed by the galaxy over its lifetime as NGC 1512 accreted other, smaller galaxies around it.

Dr Tobias Westmeier, from the International Centre for Radio Astronomy Research in Perth, said that while galaxy cannibalism has been known for many years, this is the first time that it has been observed in such fine detail.

“By using observations from both ground and space based telescopes we were able to piece together a detailed history for this galaxy and better understand how interactions and mergers with other galaxies have affected its evolution and the rate at which it formed stars,” he said.

The team’s successful and novel approach to investigating how galaxies grow is being used in a new program to further refine the best models of galaxy evolution.

For this work the astronomers used spectroscopic data from the AAT at Siding Spring Observatory in Australia to measure the chemical distribution around the galaxies. They identified the diffuse gas around the dual galaxy system using Australian Telescope Compact Array (ATCA) radio observations. In addition, they identified regions of new star formation with data from the Galaxy Evolution Explorer (GALEX) orbiting space telescope.

“The unique combination of these data provide a very powerful tool to disentangle the nature and evolution of galaxies,” said Dr López-Sánchez.

“We will observe several more galaxies using the same proven techniques to improve our understanding of the past behaviour of galaxies in the local Universe.”

A chemical enrichment map of the NGC 1512 and NGC 1510 galaxy system showing the amount of oxygen gas in the star-forming regions around the two galaxies.

Full Press Release: here.

Wednesday, May 13, 2015

I'm speaking around sydney

if youre in sydney and want to hear some sciencey astro goodness - i'm speaking at a few events you can attend in the next week and a half. I'll think i'll be incredibly exhausted by the end of this run, but i'm really looking forward to ALL the events.  let me know if you will be attending any!

1) The Storytelling of Science - Saturday, 16 May 2015, 2-5pm
2) Pint of Science - Tuesday, 19 May 2015, Doors Open at 6:30 for 7pm start
3) Astronomy Open Night at Macquarie Uni- Saturday, 23 May 2015, 6:30-10pm
4) The Story of Light - The Astronomer's Perspective - Sunday, 24 May 2015, 2 - 3:30 pm

details below....