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The Oldest Star in the Universe? --"A Primeval Dwarf Galaxy Sucked into the Emerging Milky Way"

 

 

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"We have found that this is the oldest known star with a well-determined age," said Howard Bond of Pennsylvania State University and the Space Telescope Science Institute. 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. But earlier estimates from observations dating back to 2000 placed the star as old as 16 billion years, an age range that presented a potential dilemma for cosmologists.

This Methuselah star has seen many changes over its long life. It was likely born in a primeval dwarf galaxy. The dwarf galaxy eventually was gravitationally shredded and sucked in by the emerging Milky Way over 12 billion years ago. The star retains its elongated orbit from that cannibalism event. Therefore, it's just passing through the solar neighborhood at a rocket-like speed of 800,000 miles per hour.

"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.

This "Methuselah star," cataloged as H D 140283, has been known about for more than a century because of its fast motion across the sky. The high rate of motion is evidence that the star is simply a visitor to our stellar neighborhood. Its orbit carries it down through the plane of our galaxy from the ancient halo of stars that encircle the Milky Way, and will eventually slingshot back to the galactic halo.

Because the aging star is relatively nearby, familiar stars and constellations as seen from Earth are in the sky, but in different locations. At upper left is the constellation Orion, which looks distorted from our new perspective in space. Just to the upper left of the foreground star is the Pleiades cluster. To the lower left of the cluster, our Sun has dimmed to an apparent magnitude of +7, placing it below naked-eye visibility.

This conclusion was bolstered by the 1950s astronomers who were able to measure a deficiency of heavier elements in the star as compared to other stars in our galactic neighborhood. The halo stars are among the first inhabitants of our galaxy and collectively represent an older population from the stars, like our sun, that formed later in the disk. This means that the star formed at a very early time before the universe was largely "polluted" with heavier elements forged inside stars through nucleosynthesis. (The Methuselah star has an anemic 1/250th as much of the heavy element content of our sun and other stars in our solar neighborhood.)

The star, which is at the very first stages of expanding into a red giant, can be seen with binoculars as a 7th-magnitude object in the constellation Libra. Hubble's observational prowess was used to refine the distance to the star, which comes out to be 190.1 light-years. Bond and his team performed this measurement by using trigonometric parallax, where an apparent shift in the position of a star is caused by a change in the observer's position.

The parallax of nearby stars can be measured by observing them from opposite points in Earth's orbit around the sun. The star's true distance from Earth can then be precisely calculated through straightforward triangulation. Once the true distance is known, an exact value for the star's intrinsic brightness can be calculated. Knowing a star's intrinsic brightness is a fundamental prerequisite to estimating its age.

Before the Hubble observation, the European Space Agency's Hipparcos satellite made a precise measurement of the star's parallax, but with an age measurement uncertainty of 2 billion years. One of Hubble's three Fine Guidance Sensors measured the position of the Methuselah star.

It turns out that the star's parallax came out to be virtually identical to the Hipparcos measurements. But Hubble's precision is five times better that than of Hipparcos. Bond's team managed to shrink the uncertainty so that the age estimate was five times more precise. With a better handle on the star's brightness Bond's team refined the star's age by applying contemporary theories about the star's burn rate, chemical abundances, and internal structure. New ideas are that leftover helium diffuses deeper into the core and so the star has less hydrogen to burn via nuclear fusion. This means it uses fuel faster and that correspondingly lowers the age.

Also, the star has a higher than predicted oxygen-to-iron ratio, and this too lowers the age. Bond thinks that further oxygen measurement could reduce the star's age even more, because the star would have formed at a slightly later time when the universe was richer in oxygen abundance. Lowering the upper age limit would make the star unequivocally younger than the universe.

"Put all of those ingredients together and you get an age of 14.5 billion years, with a residual uncertainty that makes the star's age compatible with the age of the universe," said Bond. "This is the best star in the sky to do precision age calculations by virtue of its closeness and brightness."

It takes just 1,500 years to traverse a piece of sky with the angular width of the full Moon. The star's proper motion angular rate is so fast (0.13 milliarcseconds an hour) that Hubble could actually photograph its movement in literally a few hours.

Journal reference: Astrophysical Journal Letters

The Daily Galaxy via NASA's Goddard Space Flight Center

 

Comments

This is a great mystery to have and shows this neighbourhood in space, still as many unanswered questions.

The opening paragraph says it all: "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. But earlier estimates from observations dating back to 2000 placed the star as old as 16 billion years, an age range that presented a potential dilemma for cosmologists."

Fudge the age of the star as much as they want, the fact is (as the data shows) the star is older than the whole universe, according to the BB theory. There are no ways around it now. The hallowed 13.8 b/y age of the universe is wrong. I remember reading 30 years ago that it was common knowledge that stars in globular cluster to range from 16 to 20 b/y in age--but that all got quashed when the BB crowd shouted down the dissenters (dissenters who had all kinds of data that anyone could look at). There are massively redshifted galaxies at 12.4 b/y, that clearly took billions of years to form, yet the BB people (all tenured professors with a lot to lose--mostly fame and sense of importance) still hold onto the idea that it's everything else that's wrong, not the BB theory. The facts of these individual stars and faraway galaxies show a much, much older universe.

@Paul Cook
Those of us with scientific training and an open mind can see many currently-accepted establishment "beliefs" are demonstrably wrong, but the establishment (the BB crowd, the LIGO lot, the Dark Matter seekers, and all the rest of the "scientists" with their feet in the trough) marshal all their forces and their army of acolytes to ridicule any ideas or theories which threaten the status quo.

Those of us with scientific training and an open mind would like evidence before discarding theories which match the data to a high degree of precision. The above measurements are not incompatible with the BB timescale, the error bars on this are quite huge though, especially compared to the Planck data.

The dating of stars age are based on a whole lot of assumptions, evidenced by the large error in the measurement.

I have scientific training and an opened mind. What I see is a big bang having a center in a larger universe with no center. The big bang is therefore much older (not to speak about the universe) and there is no dark energy but a deceleration. You want evidences: Planck data; seeming variation of the fine structure constant at cosmic scale (John Webb); fully formed galaxies at greater distances than 10-11 billion ly. In fact, even if a galaxy is really 50 billion ly from us (if we could see it), the actual model would put it at around 13.x billion ly because it is the limit of the model.

Open your mind and try to break the limit sometimes...

And I forgot the best evidence of all: the absence of Dark Energy in laboratories. Because there is no Dark Energy like there is no dark side of the moon. This is an illusion of the mind in a closed circumvolution.

How is it possible? A center to the big bang?

It just didn't start from a singularity!

Um, pardon me, but what is the meaning of this? That there is here a contradiction which we are all blind and unable to see? Well then, just point this out. There is no need for fancy theories about establishments and professors.

What I see here is evidence in need of better precision. Anything else, comes from less than appropriate understanding.
=

I always found it hard to believe that this universe can only be 13.8 B years. How about the fact that the Universe always existed and will continue to do so.

What if we discovered galaxies 20+ B LYs away with newer more sophisticated telescopes? What will happen to the 13.8 B yrs theory of the universe? The scientists will move the goal post... lol

WIll anyone call me out on this that this not possible?

remember galileo.....1633 is not so long ago that our minds have opened or learned from his fight

The high rate of motion is evidence that the star is simply a visitor to our stellar neighborhood. Its orbit carries it down through the plane of our galaxy from the ancient halo of stars that encircle the Milky Way, and will eventually slingshot back to the galactic halo.

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