How old is the Milky Way? As old as "time"?

[le3119]

The latest attempt to appraise the age of our galaxy, arriving at an age older than the 13.7 billion year "surface of last scattering" established by KOBE. I'm intrigued by the debate over the galaxy's age, because we seem to find stars that should be older than the galaxy, and a Milky Way that should be older than the 13.7 billion year date when photons "decoupled" allowing space to be transparant. A Univ. of Chicago researcher puts the galaxy's age at 14.5 billion years. <br /><br />I sometimes think that some modern structures of the cosmos unfolded out of a singularity, instead of forming according to the conventional Big Bang model. Red dwarfs like Proxima Centauri could be 15 billion years old, but even if they are reasonably younger than 13 billion years, their planets would be different than ours - composed of lighter elements, before the pre-modern epoch of nucleosynthesis, when the big supernovae cooked up the atoms heavier than iron. <br /><br />From July 1, 2005: http://www.sciencedaily.com/releases/2005/06/050630064319.htm

 

[majornature]

I think the milky way is much younger but possibly older than Earth. The Milky Way would probably be in a range of 5 billion to 8 billion years old. <br /><br /><b> True Knowledge Exists in Knowing That You Know NOTHING!!!!!</b> <div class="Discussion_UserSignature"> <font size="2" color="#14ea50"><strong><font size="1">We are born.  We live.  We experiment.  We rot.  We die.  and the whole process starts all over again!  Imagine That!</font><br /><br /><br /><img id="6e5c6b4c-0657-47dd-9476-1fbb47938264" style="width:176px;height:247px" src="http://sitelife.space.com/ver1.0/Content/images/store/14/4/6e5c6b4c-0657-47dd-9476-1fbb47938264.Large.jpg" alt="blog post photo" width="276" height="440" /><br /></strong></font> </div>

 

[labguy]

Here's another one that used Beryllium as the "yardstick"<br /><br />http://www.eso.org/outreach/press-rel/pr-2004/pr-20-04.html

 

[majornature]

Great information but it just estimates. Is this a certain factor that the Milky Way is younger than the Earth or can there be more calculations concerning the true age of our Milky Way?<br /><br /><b> True Knowledge Exists in Knowing That You Know NOTHING!!!!!</b> <div class="Discussion_UserSignature"> <font size="2" color="#14ea50"><strong><font size="1">We are born.  We live.  We experiment.  We rot.  We die.  and the whole process starts all over again!  Imagine That!</font><br /><br /><br /><img id="6e5c6b4c-0657-47dd-9476-1fbb47938264" style="width:176px;height:247px" src="http://sitelife.space.com/ver1.0/Content/images/store/14/4/6e5c6b4c-0657-47dd-9476-1fbb47938264.Large.jpg" alt="blog post photo" width="276" height="440" /><br /></strong></font> </div>

 

[rhodan]

This is what google spewed out: BBC: <ul type="square">Stars reveal the Milky Way's age<br /><br />By Paul Rincon <br />BBC News Online science staff <br /><br />Astronomers have used measurements from two distant stars to come up with an age for our galaxy, the Milky Way. <br />A team working with the Very Large Telescope (VLT) in Chile report that our galaxy is 13.6 billion years old, give or take 800 million years. <br /><br />This was determined by measuring the amount of the element beryllium in two stars in a so-called globular cluster. <br /><br />The beryllium content of stars rises with time, so it can be used as a "cosmic clock" to calculate their ages. <br /><br />"This is the first time we have obtained an independent determination of this fundamental value," said team member Daniele Galli of INAF-Observatorio di Arcetri in Florence, Italy. <br /><br />The researchers studied two stars called A0228 and A2111 in the globular cluster NGC 6397.<br /><br />...</ul>More at the link.

 

[ehs40]

i think the best wat to find the true age of the milky way it to look at the stars closest to the galatic core as possible

 

[robnissen]

Looking at stars at the galactic center is probably an especially poor place to try to measure the age of the Milky Way. The galactic center is going to tend to be much more dense in terms of dust and gas, than the galactic halo. Dense regions form large stars, large stars have very short life spans, so the vast majority of the stars in the galactic center are going to be 2nd, 3rd, 4th or even later generations of stars. The best place to look is where the stars are all first generation stars, which are going to be small stars formed in areas of relatively low density such as the galactic halo.

 

[serak_the_preparer]

<i>Stars reveal the Milky Way's age </i><br /><br />Kind of a cool update on that angle from our own Space.com: Ancient Star Nearly as Old as the Universe by Ker Than.<br /><br />Some other links, starting with the source itself:<br /><br />A Galactic Fossil by Henri Boffin (ESO)<br /><br />And this from <i>Nature</i>:<br /><br />Spying on the oldest stars in the Universe by Katharine Sanderson<br /><br /><b>What's been found?</b><br /><br />A star, with the not-so catchy name of HE 1523-0901, that's estimated to be 13.2 billion years old (plus or minus 2 billion years) — almost as old as our 13.7-billion-year-old Universe. Despite being so old, it's quite nearby; it's in our Galaxy of the Milky Way.<br /><br /><b>Did we know that stars can be that old?</b><br /><br />Yes — other really old stars have been found, such as the ancient CS 31082-001, estimated to be 14 billion years old. <br /><br /><b>Isn't that older than the Universe?</b><br /><br />Well, yes, but that age estimate comes with an error bar of plus or minus 3 billion years. So (presumably) it's not actually older than the Universe it sits in. The first generation of stars are thought to have formed a few hundred million years after the Big Bang. Both of these ancients are probably slightly younger than that, forming roughly half a billion years after the big bang....<br /><br /><b>Visit our newsblog to read and post comments about this story.</b><br /><br />(The <i>Nature</i> link has the rest of the Q&A...for awhile. Their links tend to expire.)

 

[dragon04]

<font color="yellow">Yes — other really old stars have been found, such as the ancient CS 31082-001, estimated to be 14 billion years old.</font><br /><br />I find it intriguing that we detect 13GY old stars that old that aren't 13 billion light years distant.<br /><br />How would one explain a 13 billion year old star in a 10 billion year old galaxy, for example?<br /><br /> <div class="Discussion_UserSignature"> <em>"2012.. Year of the Dragon!! Get on the Dragon Wagon!".</em> </div>

 

[docm]

A free-ranging ancient star, as the originals would likely be, could have been gravitationally captured by a passing galaxy that happened to be younger. That or it's just 'passing through' and our snapshot caught it in situ. Doppler should detect that. <div class="Discussion_UserSignature"> </div>

 

[dragon04]

<font color="yellow">A free-ranging ancient star, as the originals would likely be, could have been gravitationally captured by a passing galaxy that happened to be younger. That or it's just 'passing through' and our snapshot caught it in situ. Doppler should detect that.</font><br /><br />Well there you go. For some reason, that possibility escaped me. What I was thinking is that using the Big Bang as we think of it, the "primordial" hydrogen as we know it that formed first generation stars would have been on its way "out" well in advance of the stuff we're made of.<br /><br />And yes, I know. A tiny percentage of all the galaxies are blue shifted relative to our perspective and that one of these ancient beasts could have been ejected from one of them.<br /><br />But I'm thinking in time scale here. IIRC, our galaxy is believed to be about 10GY old, giver or take a billion or so.<br /><br />Of the blue shifted galaxies we know of, how far is the closest one (other than Andromeda) and how old are they?<br /><br />I'm inclined to take the possibility that your rational explanation is good enough, mind you, but I still wonder. <br /> <div class="Discussion_UserSignature"> <em>"2012.. Year of the Dragon!! Get on the Dragon Wagon!".</em> </div>

 

[serak_the_preparer]

<i>I find it intriguing that we detect 13GY old stars that old that aren't 13 billion light years distant.</i><br /><br />I suppose, in this case at least, that the answer is a yardstick other than light-years, redshift, etc., was used. Very cool graphic was used by ESO to accompany its article: The Cosmic Clock/Uranium in the Spectrum of an Old Star. Radioactive decay and the abundances of thorium, uranium and other elements tell the tale instead: '<i>Ever since the star was born, these "clocks" have ticked away over the eons, unaffected by the turbulent history of the Milky Way. They now read 13.2 billion years.</i>'<br /><br />Rhodan's BBC article discusses work done at the Very Large Telescope at the Paranal Observatory in Chile, which indicates our Milky Way to be a very ancient object: 13.6 billion years old. ESO's press release: How Old is the Milky Way? From its summary:<br /><br /><i>The age of the stars in NGC 6397, as determined by means of stellar evolution models, is 13,400 ± 800 million years. Adding the two time intervals gives the age of the Milky Way, 13,600 ± 800 million years.<br /><br />The currently best estimate of the age of the Universe, as deduced, e.g., from measurements of the Cosmic Microwave Background, is 13,700 million years. The new observations thus indicate that the first generation of stars in the Milky Way galaxy formed soon after the end of the ~200 million-year long "Dark Ages" that succeeded the Big Bang.</i><br /><br />This is the actual paper: Beryllium in turn-off stars of NGC 6397: early Galaxy spallation, cosmochronology and cluster formation (ps) by L. Pasquini, P. Bonifacio, S. Randich, D. Galli, and R. G. Gratton (Astronomy & Astrophysics).

 

[dragon04]

Thanks for the links. The first one in particular is very beneficial.<br /><br />It assumes (or knows) that the MW is as old or a tiny bit ilder than this star. I was working off the assumption that the MW was significantly "younger" by about 2 or 3 GY.<br /><br />Despite certain general and specific criticism, this is exactly why I read the Science Fora far more than I post on them. I could probably teach a 4th grade Astronomy class, but in these waters, I'm a guppy in the shark tank. <img src="/images/icons/wink.gif" /> <div class="Discussion_UserSignature"> <em>"2012.. Year of the Dragon!! Get on the Dragon Wagon!".</em> </div>

 

[serak_the_preparer]

<i>I'm a guppy in the shark tank.</i><br /><br />As am I, and this is one of the loves of my life. Agree with DocM about the rogue stars. So at what point do we scrutinize our definition of 'galaxy' and say something like, 'the oldest detectable thing in any galaxy defines its alleged "age"'?<br /><br />We appear to reside in a very 'aggressive,' 'carnivorous' or 'cannibalistic' galaxy. Please forgive the anthropomorhpic description. However our galaxy has evolved, its evolution seems to go back almost right back to the very beginning, one of the original galaxies of our universe.<br /><br />New Map of the Milky Way Shows Our Galaxy to be a Cannibal by Fariss Samarrai (University of Virginia)<br /><br />September 24, 2003<br /><br /><i>. . . "Whenever possible, astronomers appeal to the principle that we are not at a special time or place in the universe," Majewski said. "Because over the 14 billion-year history of the Milky Way it is unlikely that we would just happen to catch a brief event like the death of Sagittarius, we infer that such events must be common in the life of big spiral galaxies like our own. The Milky Way probably dined on a number of dwarf galaxy snacks in the past...."</i><br /><br />We are not as 'new' as we may sometimes be inclined to think we are. Our history, our direct line-of-descent, runs right back to the very beginning.

 

[dragon04]

And there's no definitive proof as to the true age of the Universe. We can only gauge that on what we can observe.<br /><br />However, I wonder given the cosmological revelation that the Universe is not only still expanding, but that the expansion is accelerating, how can we divine to any certainty how big and how old the Universe as we know it really is?<br /><br />By what we know and what we observe, superluminal recession doesn't seem to be the stuff of Sci Fi. So how much matter is out there that we cannot and might never see?<br /><br />Even if matter is only loosely distributed in anything that resembles an even way, the very first atom that we can't see beyond the visible boundary would imply a significantly massive amount of unaccounted for matter by conventional means and might render explanations that include "dark matter" null and void.<br /><br />Conventional wisdom can't find enough matter to explain what we observe in anything that resembles mundane terms. So does that require and exotic explanation that includes dark matter and dark energy, of is the Universe simply bigger than we can observe?<br /><br />And more importantly, is there anyone out there that thinks in those terms? <div class="Discussion_UserSignature"> <em>"2012.. Year of the Dragon!! Get on the Dragon Wagon!".</em> </div>

 

[serak_the_preparer]

<i>So how much matter is out there that we cannot and might never see...?<br /><br />So does that require and exotic explanation that includes dark matter and dark energy, of is the Universe simply bigger than we can observe? <br /><br />And more importantly, is there anyone out there that thinks in those terms?</i><br /><br />Max Tegmark may be the guy you're looking for:<br /><br />Parallel Universes by Max Tegmark (MIT)<br /><br />(See also: Parallel Universes by Max Tegmark (Scientific American))<br /><br />The Mathematical Universe (pdf) by Max Tegmark (MIT)

 

[serak_the_preparer]

Just came across another link. Ours may be a big galaxy, and a very old one, all right - but it's still growing.<br /><br />Hey, everybody: seatbelts!<br /><br />Will the Sun be stolen by another galaxy? by Jeff Kanipe (Nature)<br /><br />15 May 2007<br /><br /><i>. . . In 1959, it was determined using Kepler's laws of motion that both galaxies had traced out almost a full period of their orbital motion and were falling back together, with the next close passage occurring about 4 billion years from now.<br /><br />But that calculation was made in the days before it was realized that all galaxies are immersed in extended, massive dark-matter haloes. The added mass of the haloes makes the Milky Way and Andromeda galaxies more gravitationally attractive and this speeds up the merger process. Cox and Loeb conclude that the next close passage will occur in less than 2 billion years. <br /><br />Over a period of half a million years, the two galaxies will pass through each other, with individual stars passing through the gaps (the chances that two stars might collide are very slim). Many of the stars will be gravitationally perturbed by the collision — some may even be ripped from one Galaxy and take up residence in the other.<br /><br />After this passage, the two galaxies will swing by each other again more quickly, about 3.5 billion years from now, and will finally merge into a single blob some 5 billion years from now, Cox and Loeb say. This 'merger remnant' will be a huge, slowly rotating sphere containing several hundred billion stars. Astronomers refer to these galactic specimens as low-to-medium-luminosity elliptical galaxies. Cox and Loeb give this one the name Milkomeda....</i><br /><br />Once Milkomeda forms, the gentlemen from Harvard claim there is a 68% chance our Sun will be ejected from its home galaxy.<br /><br />'Milkomeda' doesn't work too well for me. I like the sound of 'Andromew

 

[MeteorWayne]

And 5 billion years from now, no one will care what names we preferred <img src="/images/icons/laugh.gif" /> <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[renato24]

haha good one MW.

 

[eso44527]

The oldest structures in the Milky Way are globular clusters with ages typically in the range of 10-13 billion years. Salaris&Weiss demonstrated this in 2002. However, it is possible that the Milky Way is not as old as the universe. For example, Bregman et al (2006) found that ~27% of the elliptical galaxies in their sample had ages from 15.9 to 20.6 billion years. Because these ages are in obvious disagreement with the favored lamda-CDM cosmology parameters they shifted the ages of their models to fit the concordance cosmology.