September 19, 2019

Astro-Challenge of the Week: Can you Spot the Brightest Quasar?

This week, we here at Astroguyz are going to show you how to go after that most elusive of beasts; a quasar. Even seasoned amateurs do not always realize that some of the brighter denizens of this elusive class of beasts are bag-able with a telescope of moderate-sized aperture. Of course, don’t expect to see much; part of the fun of this challenge is the fact you can see it at all, and the wonder of what the object actually is. Our visual prey is 3C 273 is the constellation Virgo. This object was the 273th listed in the 3rd Cambridge Catalog of radio sources, and at a 16% red-shift, stands at “only” about 2 billion light years distant! This also gives it an apparent recessional velocity of 30,000 miles per second. Visually, 3C 273 hovers at about magnitude +12.2, although it has been known to vary by about magnitude 0.5 in either direction. Its coordinates are;

Right Ascension: 12 Hours 29 minutes 6 seconds.

Declination: +02° 03’ 06” N

A good series of finder charts courtesy of the AAVSO may be had here; 3C 273 is about 4.7° NW of the star Gamma Virginis and very near the galaxy NGC 4536.

Now for the mind-blowing part; the absolute magnitude of 3C 273 is about -26; if this object was 10 parsecs distant, it would visually rival our own Sun! Its output also tops our own Milky Way galaxy by a factor of x100! As you can see, writing a post on the topic of quasars demands the extreme over-usage of exclamation points. 3C 273 is a worthy target for aperture 6” or greater, and stands as the farthest object you’ll probably ever lay eyes on. It also serves as a good reply to that common neophyte question heard at star parties; “So, how far can you see with that thing?” And just think, the light left 3C 273 when the Proterozoic era was the newest, greatest thing here on Earth… imaging may even help you grab this beast. Amateurs have even successfully recorded a spectrum of 3C 273 and measured its red-shift, a good reply next time someone asks you; “Yeah, but how do YOU know the universe is expanding?”  As the waning Moon slides out of the evening sky, I invite you add a quasar to your visual athlete-life list!

This week’s astro-word of the week is Quasar. Short for Quasi-Stellar object, this class of amazing objects was not even heard of until the early 1960s. Much controversy raged for decades as to exactly what astronomers were seeing; theories ranged from white holes to anti-matter fueled stars in the early universe. With the advent of accretion disc theory as a massive energy source outlined in the 1970’s a model of quasars slowly emerged; the consensus now is that we are seeing highly energetic galactic nuclei early in their youth. Perhaps the supermassive black hole at the core of our own Milky Way Galaxy was once a quasar itself, gobbling up interstellar matter and emitting massive amounts of x-rays and radio waves before settling down to the relatively placid state we see today. Other classes of objects such as blazars and radio galaxies have further filled in the classification gaps, and the massive amounts of energy we see in some quasars are thought to simply be the result of our viewing angle here on Earth. The brightest quasars devour perhaps 1000 solar masses of material a year, and the most distant recorded is CFHQS J2329-0301 discovered in 2007, with a red-shift of 6.43 and about 13 billion light years distant. This puts it in the realm of the very early universe, which is only 13.7 billion years old!

02.05.10- Star-birth in the Early Universe.

Astronomers are shedding new light across the spectrum on an old cosmological mystery. It’s well documented that the rate of star formation today is much less than what it was early on in the history of the universe; what isn’t completely understood is why. Was there simply an abundance of star forming material available, or was the process of star formation more efficient? Either trend may have a huge significance as to how the current and future evolution of the universe plays out; stars such as our Sun are metal rich and formed as a result of the recycling of cosmic material from that first primeval generation of stars. Even non-fusion sustaining bodies such as the Earth, Sandra Bullock, and your IPad owe their elemental composition largely to those original stars.  Now, a team led by Michael Cooper of the University of Arizona’s Steward Observatory is tackling the dilemma from a fresh angle. The galaxies in question are about 4 billion years old; the universe is an estimated 13.7 billion years of age. In that tender young era, the rate of observed star formation was about 10 times what we see today. Traditional surveys have looked at larger, brighter, and more easily observable galaxies in the energetic throes of star formation. But is that the best approach? This method largely ignores the vast population of fainter, harder to spot galaxies. “It is a little like studying only individuals who are seven feet tall instead of those who fall in a more common range of height,” stated Cooper. Their unique approach has been to examine a selection of average galaxies culled from 50,000 objects to study across a range of wavelengths. Instruments called into action included the Hubble and Spitzer Space telescopes as well as an array of ground-based radio telescopes. Analysis across the spectrum shows that a much greater concentration of gas and dust was available to fuel star formation than what we see today; these galaxies also really light up in the radio and infrared, as pictured above… could we be looking at snapshots resembling our galaxies’ grandparents?

Review: The Five Ages of the Universe by Fred Adams and Greg Laughlin.

This week, we’re going to look at a classic book on cosmology that is both fascinating and frightening. About 10 years ago, I read the Five Ages of the Universe by Fred Adams and Greg Laughlin.  This book built upon information gathered in the swiftly growing field of cosmology, a science that has just come into its own from one largely of late night philosophy to one of hard science with real observational data. Five Ages does nothing short of trace the history of the universe from its first moments to its logical end, or lack thereof. The discovery that we appear to live in an open universe that will indeed expand ad infinitum holds some very bizarre and disconcerting conclusions, all of which the authors explore in vivid detail using the most up-to-date data available. It’s strange to think that we may occupy a tiny sliver of space and time where life can occur, and a vast, infinite stretch of nothing may be in store. However, the authors are careful to make every attempt to abandon their own human bias towards the current era, and instead look at subsequent epochs on their own terms.

When dealing with a topic as expansive as the history and fate of the universe, one has to become accustomed to discussing extremely large numbers. Creationists aside, we live in a universe that is about 13.7 billion years old, give or take about 100 million years. But that is peanuts compared to the gargantuan timescales discussed in this book. Instead, the authors resort to what are termed cosmological decades, (henceforth called CDs) exponential scales where each decade is ten times longer than the last. Thus we are said to exist at the very beginning of the 10th decade, or 1010, which began 3.7 billion years ago and will last until decade 11 over 96 billion years from now. And trust me, the time scales just get larger from there…

The first era covered is termed the primordial epoch, from the moment time and space began until CD 6. During this time of rapid inflation matter coalesced via nucleosythesis, the cosmic microwave background separated out the cooling universe, and the first stars began to shine.

The next era explored is our own, termed the stelliferous era. This is the time we see today and are most familiar with. Stars shine via fusion, galaxies collide, and the processes that power life that is possible to contemplate the wonder of it all and write books (and blogs about books!) is possible. During this period, which is expected to last up until about CD 15, stars will pass through their life cycle until the universe is littered with white dwarfs, pulsars, and black holes. Miserly red dwarf stars, with an expected fusion producing life span of up to about 10 trillion years are expected to be the last stars to go. Then the universe gets really weird…

From CD 15-40 we enter what is known as the degenerate era, a time when white dwarfs turn black, protons decay, and dark matter annihilates the galactic halo. Perhaps an occasional brown dwarf pair will merge in this far-off time and an old school star will shine briefly in the void. But by CD 40, the start of the black hole era, only the stellar remnants of black holes will remain. Even these are anticipated to decay via the process of Hawking radiation with even one million solar mass monsters dissipating after around CD 83. Axions are also predicted to decay into photons at about this time.

Of course, what happens during the final dark era of about CD100 on is highly speculative. Will time itself cease to exist? Will quantum fluctuations randomly spout new universes? Will a sort of cosmological phase transition reconstruct our present universe? Keep in mind, long before this time, the edge of the observable universe will have expanded to a mindboggling point, as if it’s not brain blowing big enough now. In fact, the distance between whatever passes for individual particles in the far off dark era will be larger than the observable universe today!

Read The Five Ages of the Universe to gain a cosmic perspective on the consequences of just what living in an infinite universe might mean. Each chapter also opens with an engaging “you are there” narrative to help gain a perspective on these alien realms through the forces propelling the universe through its transitions. Perhaps I would first read Stephen Hawkings’ landmark A Brief History of Time to provide some background, and then follow up Ages with Douglas Adams Hitch-hikers Guide to the Galaxy as a way to cheer oneself up as to the inevitability of it all!

 

12 Amazing Moments in Science.

Let it be known that this post did indeed start with 12… whenever someone mentions the most exalted achievements of mankind, the topic usually comes around to science. Along with our art and music, we’re the only animals that will know of that routinely apply the scientific method to the universe around us. And yet, some scientific discoveries weren’t supposed to be made, and their advent catapulted us years ahead of our time, or at least had the potential to do so, if only they had been recognized. What follows is a list of surreptitious, un-authorized, or just plain awesome discoveries that gave us some key insight into the nature of reality. Just like in the Wizard of Oz, most scientists work for their entire lives just to get a brief glimpse of the man behind the curtain. Anyway, we tried to be as fair as possible and include examples from a cross-section of scientific disciplines; we also tried to include the rare but true tales alongside the ones everybody knows. If your fave didn’t make the cut, let us know; there’s certainly cyber-space for a part II! Thanks also to those intrepid readers who sent in their suggestions; you rock, as always…

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25.10.09: In Search of a Mirror Universe.

There is one enduring mystery in cosmology that just won’t budge; namely, just what happened to all that pesky anti-matter that was presumably created during the Big Bang? Was it annihilated, only to leave the infinitesimally small faction of pedestrian “normal” baryonic matter that comprises the universe that we know and love, or are there still areas that antimatter predominates? Now, cosmologists are getting their wish in the form of the Alpha Magnetic Spectrometer (AMS), due to launch aboard the last shuttle flight and bound for the International Space Station late next year. Once installed, AMS will search the entire sky with an unprecedented accuracy looking for ultra-high energy cosmic rays in the form of anti-helium nuclei. Antimatter looks and behaves just like normal matter…except when it meets up with its mirror cousin. If you meet your anti-matter twin on the road, don’t shake hands with him or her, our you’ll both vanish in a flash of pure energy conversion Ala E=mc^2! The AMS will also look for such exotica as dark matter, micro-quasars, and strangelets, a proposed new form of matter. And that’s just the stuff we know about! I smell a possible Nobel in the works…are you reading this, CERN? The AMS has been an on-again, off-again payload that Congress just green-lighted last year. The AMS promises to reveal a big old, bizarre universe out there. With a sensitivity 200 times anything that’s flown previous, AMS should conclusively prove or disprove the potential existence of any lurking antimatter galaxies out to a radius of 100 mega-parsecs. Like CERN, AMS will also generate terabytes of data to keep astrophysicists awake nights, and will be a fitting end to the shuttle fleets’ career!

 

 

4.10.9:A Gamma-Ray Burst for the Record Books.

A Gamma-ray burst from the primordial universe sent astronomers reeling earlier this year with the most distant sighting yet. The burst was picked up by NASA’s Swift spacecraft on April 23, 2009 at 3:55 EDT. E-mails and instant messages flew to observatories around the globe as astronomers raced to pin-point the fading afterglow. Dubbed GRB 090423, (get the year/month/day thing?) This burst measures in at a redshift of 8.2, or a distance of 13.035 billion light years. This hails from a time when the universe was a tender young age of only 630 years old, young, compared to our circa 14 billion year current age. The old record was a red shift of 6.7 set in September 2008. the current “holy grail” in cosmology is to break the “redshift 10″ barrier, which may well happen in the coming year. A gamma-ray burst occurs when a super massive star collapses into a black hole, briefly creating a “hyper-nova” in the process. Such events are the most luminous in the universe and are thought to have been common amoung first generation stars. Backup observations were provided by Italy’s Galileo national telescope in the Canary Islands and the ESO’s Very Large Telescope in Chile.

Review: Bang!

 

 

Think hard rock and astrophysics don’t mix? Think again. Recently, we had the pleasure of reading Bang! The Complete History of the Universe,” by astronomy heavyweights Brian May, Patrick Moore, and Chris Lincott… [Read more...]