Archive for the ‘Telescopes’ Category
There has been a debate about the distance to the Pleiades cluster that has been going for decades. Although it appears to have been resolved, well this is the claim of a team of radio astronomers in the US, who concluded that the cluster is approximately as far away as originally estimated. This contradicts analyses made form data from the Hipparcos, which suggested that the cluster is 13 parsecs closer than astronomical models predict.
The Pleiades is the star cluster most obvious to the naked eye in the night sky, and has been known since antiquity. In modern astronomy. It often appears low in the horizon in the Southern hemisphere. The distance to the Pleiades is used to calibrate the cosmic-distance ladder, allowing astronomers to calculate distances to other star clusters and galaxies that are further away. And so, it is important to know the distance to Pleiades precisely, and multiple calculations of it have been made using various methods by various researchers over the decades.
Currently the generally accepted distance was about 134 parsecs (about 437 light-years). Yet in 1999, Floor van Leeuwen of the Institute of Astronomy in Cambridge, UK, used data from the European Space Agency’s Hipparcos satellite to produce what was the most precise calculation to date. This estimate was obtained using trigonometric parallax. Van Leeuven arrived at a distance of about 120 parsecs, and in 2009 he refined his analysis but reached a similar conclusion.
In new research by Carl Melis of the University of California, San Diego and colleagues at several other US institutions, they did their own trigonometric-parallax measurement of five selected stars in the Pleiades cluster using very long baseline radio interferometry. In this technique, measurements are made by linked radio antennas spread across the world, giving the total resolution of a telescope the size of the Earth. The researchers found that the distances of all five stars were in broad agreement with the original figure, with the lowest value being 134.8 parsecs and the highest being 138.4.
However in 2013 ESA launched Gaia, a successor to Hipparcos with much higher specifications, such as higher-sensitivity cameras, that will measure the parallaxes of thousands of stars in the Pleiades cluster. The design principles are conceptually similar, which leads Melis and colleagues to suggest that the unidentified error they believe distorted the Hipparcos measurements of the Pleiades could also affect Gaia. Nevertheless, Melis suspects that “the Gaia measurement is not going to be the same as the Hipparcos measurement. Hopefully then the Hipparcos community is going to have to face the fact that Hipparcos did not produce the correct result.”
See the paper at Science: http://www.sciencemag.org/content/345/6200/1029
In November 2012, a new distance record breaker has been weighed in with a photometric redshift of z ~ 10.8 which is roughtly 420 million years after the big bang. This is pretty significant.
The Cluster Lensing and Supernova survey with Hubble (CLASH), and the Spitzer/IRAC has measured the photometric redshift and with the help of Gravitational Lensing has been able to see the object by it’s increased visability and determined its distance.
The paper on the object, together with 2 other distance candidates, can be viewed (in full if you have access) on ApJ: http://iopscience.iop.org/0004-637X/762/1/32 or you can get a pre-print on ArXiv which is almost the same as the ApJ paper: http://arxiv.org/pdf/1211.3663v1.pdf
MACS0647-JD is the one of the three with the largest redshift, and a Lyman Break Galaxy. The light from the relic galaxy, at the time of transmission, was so small and may have been in the first stages of forming a larger galaxy.
* Comet PANSTARRS (C/2011 L4) in Cetus * Photo By Humayun Qureshi. Taken from Canberra.
Astronomers discovered Comet PANSTARRS (C/2011 L4) on June 7, 2011. In early February, the comet reached its southernmost point, but by the end of May it will lie near Polaris (Alpha [α] Ursae Minoris).
Comet watchers should target February 21 through March 27, when the Comet PANSTARRS should shine more brightly than a 2nd-magnitude star (like Polaris). On March 5, the 1st-magnitude comet lies closest to Earth. Search for it after sunset 17° southeast of the Sun. Use binoculars or a rich-field telescope.
This is a Digitized Sky Survey image of the oldest star with a well-determined age in our galaxy. The aging star, cataloged as HD 140283, lies 190.1 light-years away. The Anglo-Australian Observatory (AAO) UK Schmidt telescope photographed the star in blue light. Credit: Digitized Sky Survey (DSS), STScI/AURA, Palomar/Caltech, and UKSTU/AAO
A team of astronomers using NASA’s Hubble Space Telescope has taken an important step closer to finding the birth certificate of a star that’s been around for a very long time.
“We have found that this is the oldest known star with a well-determined age,” said Howard Bond of Pennsylvania State University in University Park, Pa., and the Space Telescope Science Institute in Baltimore, Md.
The star could be as old as 14.5 billion years (plus or minus 0.8 billion years), which at first glance would make it older than the universe’s calculated age of about 13.8 billion years, an obvious dilemma. This is going to be a strom in the cosmology world, as most believe that the univsere 13.7 gigayears (billion years) old – admittedly its only an estimate, but one that will be pushed back.
But earlier estimates from observations dating back to 2000 placed the star as old as 16 billion years. And this age range presented a potential dilemma for cosmologists. “Maybe the cosmology is wrong, stellar physics is wrong, or the star’s distance is wrong,” Bond said. “So we set out to refine the distance.”
The new Hubble age estimates reduce the range of measurement uncertainty, so that the star’s age overlaps with the universe’s age — as independently determined by the rate of expansion of space, an analysis of the microwave background from the big bang, and measurements of radioactive decay.
The selection of the best site for the Square Kilometre Array (SKA), which was between South Africa and a joint Australian/New Zealand bid, surprised most people. But it makes real sense to utilize the preliminary facilities that both nations have started to contribute.
In an earlier article on RelativeCosmos.com I suggested Australia would be best but in light of the split decision, it is a welcome selection!
Australia will launch phase 1 of the plan and get started sooner and South Africa will come in a little later with phase 2. It really is a workable solution and it is coup for both countries’ astronomy communities – many details are yet to be finalised but it’s one of those great times where a turning point makes for great history.
To quote Nature, “But splitting the site does have potential benefits. For one thing, the redundancy created by international collaboration can come in handy. The ISS, for example, continues to be serviced by a slew of vehicles from its different partners, even though the US space shuttle no longer flies there. There is also a perverse financial advantage — multiple partners are less likely to cancel an over-budget project than is a single government. But the greatest benefit is human: a more complex project draws in more people from more places and gives them an opportunity to participate.”
Read more on: Nature 485, 548 (31 May 2012) doi:10.1038/485548a
By Estelle Asmodelle
Recent reports on the selection of the site for the Square Kilometre Array (SKA) have suggested that South Africa offers the best site and a panel of advisors recommended the SA site over Australia. The argument was put that the SA site was cheaper for construction, yet Australia had lower insurance fees, and primarily that the SA site was at a higher altitude.
The issue of altitude is really irrelevant here for at higher frequencies water vapour, or Scintillation (the distortion of waves moving through varying densities) can become a problem, but not so much for long radio waves, the bigger problem there is radio frequency interference. Australia would be the best place for SKA, especially in WA which is ‘radio quite,’ not so in South Africa. Most long wave radio dishes are low lying. Altitude is more important for millimetre or sub-millimetre arrays.
I think this is really a political issue, South Africa really needs help financially and the SKA would boost their economy. I just hope that Australia is chosen, for South Africa’s site is not as remote and within 10 years, of completion, the site could suffer considerable radio interference problems, which would seriously degrade its operational status.
And also South Africa has many other issues, such as social unrest which could affect the operation of the telescope, or the employees. The argument that SA would be best as they have already started building the array, but it’s also true of Australia, who under the project name ASKAP, or the Australian Square Kilometre Array Pathfinder have already deployed some of the planned 36 dishes which will be complete in 2013, and can be integrated into the SKA if Australia is chosen, some dishes have already seen first light. See the site:
ASKAP, or the Australian Square Kilometre Array Pathfinder
See the status of the ASKAP site here in real time – updated often:
Don’t take my word for it – see Brian Boyle’s burb on the advantages Australia offers for the SKA:
Some say that people who are astronomers, or students like me who will be looking for placement soon, are just feathering their nest – not true, for most of the people who will work on these sites will be from all over the world, the very cream of the crop, and probably not be Australian to a large extent.
So in fact we are further along than SA. So why the support for SA – word is, as I’ve eluded too, it’s really about politics not science – see this article:
The last thing to bear in mind – Australia will soon have the NBN rolled out all over the country – this will assist the data handling to a very large extent – certainly by the time the SKA is complete we will have one of the best broadband networks in the world!
Interestingly the last big astronomy project SA was involved in had endless imaging problems (Although an optical site), and still does to an extent, and even more recently, poor broadband and operating problems:
And read more here:
All in all the remote WA site is best suited for such an astronomical site for several reasons but most importantly the size of our site – see the map for details:
By Estelle Asmodelle
The transit of Venus is happening 5th-6th June 2012.
There are plenty of Astronomical Societies who are holding ‘transit parties,’ including two that I do presentations to: The first one, here is a page from the Newcastle Astronomical Society with their ‘transit party’ and they had ABC radio there as well:
I understand they will be doing the same thing this year… and I will be going as well.
The second is the Sutherland Astronomical Society (largest such group in Sydney) – they have their own observatory, and it’s a good one too. They too are going to have a ‘transit party’
Incidentally, I am giving a presentation to this group (in response to an invite from them after reading some of my articles in Cosmos) entitled: “Cosmology and the role of the General Theory of Relativity.” Which will be 2 nights after the transit – this will be the first time that I’ve given a presentation to this group, and I feel a bit intimidated by it as it’s a 90 minute presentation and they usually get university lecturers to do such presentations – fingers crossed that I have my ducks all in a row…
I didn’t see the 2004 transit as I was overseas at the time but I won’t miss this one! Here is an Australian site dedicated to the transit that you may find interesting as well:
Incidentally, Jeremiah Horrocks was the first person to successfully predict and observe the transit of Venus in 1639.
But the BIG news is really the total solar eclipse in Cairns, which is at the top of Queensland, that is the big news. Cairns is 3 hour flight and 2 hour drive from my home but we have our flight booked and our hotel booked ready – I am taking my two nephews as well, one is at Uni and the other is very interested in astronomy as well. Here in Australia its big news for many people and most of Cairns is booked out – I will taking my telescope and HD video camera, together with a suitable filter, to film the event – so it’s really exciting – it’s my first total eclipse. I have seen a couple of partials but never a total! Here is an Australian website with some more details:
By November it should be dry, also Cairns gets tropical rain and as the eclipse is just after sunrise it will 95% be dry, I just hope it’s clear skies!
As NASA prepares to wrap up its shuttle program, leaving open questions about what comes next for U.S. human spaceflight, the next big thing in NASA’s astronomy program has been dealt a blow. The James Webb Space Telescope, a tennis court–size spacecraft that would take up a position in deep space to peer farther than ever into the cosmos, has been in development as a replacement for and successor to the Hubble Space Telescope, which has already logged 21 years in orbit. But the House Appropriations Committee, in a bill announced July 6, proposed axing the project entirely this week, citing mismanagement and bad budgeting.
NEW METHOD OF MAPPING THE UNIVERSE USING QUASARS -BOSS.
The biggest 3-D map of the distant universe ever made, using light from 14,000 quasars – supermassive black holes at the centers of galaxies billions of light years away – has been constructed by scientists with the third Sloan Digital Sky Survey (SDSS-III).
See the Phyorg article here: http://www.physorg.com/news/2011-05-distant-universe-d-boss-job.html
Or sciencecodex here: http://www.sciencecodex.com/measuring_the_distant_universe_in_3d
THE HUNTING OF DARK MATTER
The race to detect dark matter has yielded mostly confusion. But the larger, more sensitive detectors being built could change that picture soon.
If you did yet get this PDF now is a good time to download it
Article on Nature website: http://www.nature.com/news/2011/110323/pdf/471433a.pdf
THE NEW MOST MASSIVE OBJECT – CURRENT TITLE HOLDER ANYWAY:
The most massive known object in the young universe, a galaxy cluster dubbed SPT-CLJ2106-5844, is also a probe of conditions in the young universe. This image combines optical and infrared images with intensity contours from the Chandra X-ray Observatory.
Phyorg article here: http://www.physorg.com/news/2011-04-massive-distant.html
SUPER LUMINIOUS SUPERNOVA
Images of SN 2008am obtained with the Keck I telescope’s Low Resolution Imaging Spectrometer (LRIS).Credit: D. Perley & J. Bloom / W.M. Keck Observatory
The Keck I Telescope has played a key role in unraveling the mysteries of one of the brightest supernovas ever discovered.
DOES DARK MATTER LINK GAMMA RAYS TO GALACTIC HAZE?
Annihilating dark matter at the heart of the Milky Way could account for signals detected by two space telescopes, according to a pair of US physicists.
IOP website: http://physicsworld.com/cws/article/news/45804
ANITMATTER DETECTOR READY
A heavyweight, and controversial, cosmic-ray detector is set to head for the International Space Station.
The Alpha Magnetic Spectrometer will seek antimatter in deep space, and measure cosmic rays closer to home
Nature website: http://www.nature.com/news/2011/110428/full/news.2011.260.html
THE MAGNETIC UNIVERSE
We live in a magnetic universe, but much about magnetism at cosmic scales remains unknown.
The magnetic field at the Milky Way’s core is at least 10 times stronger than that of the rest of the galaxy.
Another universe tugging on ours? Maybe not, researchers say
A new study from the University at Buffalo contradicts the dark flow theory, showing that exploding stars in different parts of the universe do not appear to be moving in sync. Working with data on 557 such stars, called supernovae, UB scientists deduced that while the supernovae closest to Earth all shared a common motion in one direction, supernovae further out were heading somewhere else. An article announcing the research results will appear in a forthcoming edition of the peer-reviewed Journal of Cosmology and Astroparticle Physics.
Astronomers mull merger of missions
Cosmic-origins scientists convene with exoplanet hunters.
NASA’s constrained budget is encouraging some creative pairings. This week, scientists eager to find other habitable worlds explored the possibility that a future space telescope for probing the origins of stars and galaxies could serve their needs as well.
Xenon100: ‘We hope to detect the largest proportion of the matter in space’
The underground laboratory at Gran Sasso in Italy is the home of the Xenon100 experiment, which is being conducted as an international collaboration that includes the Heidelberg-based Max Planck Institute for Nuclear Physics to detect the mysterious particles directly. The researchers recently published the evaluations of one hundred days of measurement time. The result: although there is no significant signal for dark matter as yet, the world’s best limits for the masses and interaction strengths of the WIMPs have been obtained, and already noticeably reach into the predicted range.
Scientists suggest spacetime has no time dimension
The concept of time as a way to measure the duration of events is not only deeply intuitive, it also plays an important role in our mathematical descriptions of physical systems. For instance, we define an object’s speed as its displacement per a given time. But some researchers theorize that this Newtonian idea of time as an absolute quantity that flows on its own, along with the idea that time is the fourth dimension of spacetime, are incorrect. They propose to replace these concepts of time with a view that corresponds more accurately to the physical world: time as a measure of the numerical order of change.
If you are interested in Exoplanets – then there are TWO good PDFs for free download from Nature this week – they are both must read documents:
Exoplanets on the cheap
The search for planets outside our Solar System will always be pricey. But creative solutions are proving that it no longer has to break the bank. Astronomers searching for planets around stars other than the Sun have had much to celebrate over the past decade. The number of confirmed ‘exoplanets’ has soared from about 50 to more than 500 in that time. And although none of these planets closely resembles Earth, NASA’s Kepler space telescope, launched in 2009, is now delivering candidates from distant stars by the hundreds — some of which may prove to be very Earth-like indeed
The search for planets outside our Solar System will always be pricey. But creative solutions are proving that it no longer has to break the bank.
BEYOND THE STARS
Launched in 2009 to seek out worlds beyond the Solar System, the Kepler mission is exceeding expectations. Is it closing in on another Earth? The Kepler space telescope is exploring a sliver of the Milky Way some 900 parsecs (about 3,000 light years) deep.
Launched in 2009 to seek out worlds beyond the Solar System, the Kepler mission is exceeding expectations. Is it closing in on another Earth?
Eugenie Samuel Reich