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One of Milky Way’s Oldest Stars Discovered
Sci-News.com ^ | Nov 6, 2018 | News Staff / Source

Posted on 11/06/2018 11:51:00 AM PST by ETL

The Universe’s first stars after the Big Bang would have consisted entirely of elements like hydrogen, helium, and small amounts of lithium.

Those stars then produced elements heavier than helium in their cores and seeded the Universe with them when they exploded as supernovae.

The next generation of stars formed from clouds of material laced with those metals, incorporating them into their makeup.

The metal content, or metallicity, of stars in the Universe increased as the cycle of star birth and death continued.

2MASS J18082002-5104378 B, also known as Gaia DR2 6702907209758894848 B, is unusual because unlike other stars with very low metal content, it is part of the Milky Way’s ‘thin disk’ — the part of the Galaxy in which our own Sun resides.

“This star is maybe one in 10 million. It tells us something very important about the first generations of stars,” said lead author Dr. Kevin Schlaufman, a researcher at the Johns Hopkins University.

The extremely low metallicity of 2MASS J18082002-5104378 B indicates that, in a cosmic family tree, it could be as little as one generation removed from the Big Bang.

Indeed, it is the new record holder for the star with the smallest complement of heavy elements — it has about the same heavy element content as the planet Mercury. In contrast, our Sun is generations down that line and has a heavy element content equal to 14 Jupiters.

Astronomers have found around 30 ancient ‘ultra metal-poor’ stars with the approximate mass of our Sun. 2MASS J18082002-5104378 B, however, is only 14% the mass of the Sun.

The star is a tiny, almost invisibly faint secondary member in the binary system 2MASS J18082002-5104378.

Dr. Schlaufma and colleagues found it after another group of astronomers discovered the much brighter ‘primary’ star.

(Excerpt) Read more at sci-news.com ...


TOPICS: Astronomy; Astronomy Picture of the Day; Chit/Chat; Science
KEYWORDS: astronomy; j180820025104378; j180820025104378b; science; xplanets
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Image result for One of Milky Way’s Oldest Stars Discovered
This image shows the binary star system 2MASS J18082002-5104378.
Image credit: Centre de Données astronomiques de Strasbourg / SIMBAD / DSS2.
1 posted on 11/06/2018 11:51:00 AM PST by ETL
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Stellar age estimation

Various methods and tools are involved in stellar age estimation, an attempt to identify within reasonable degrees of confidence what the age of a star is.

These methods include stellar evolutionary models, membership in a given star cluster or system, fitting the star with the standard spectral and luminosity classification system, and the presence of a protoplanetary disk, among others.

Nearly all of the methods of determining age require knowledge of the mass of the star, which can be known through various methods. No individual method can provide accurate results for all types of stars.[2]

Contents

1 Luminosity increase and the Hertzsprung–Russell diagram
2 Stellar age estimation of stars
3 Membership in a star cluster or system
4 Presence of a protoplanetary disk
5 Gyrochronology
6 See also
7 References
8 External links

Luminosity increase and the Hertzsprung–Russell diagram [see link]

As stars grow older, their luminosity increases at an appreciable rate.[3] Given the mass of the star, one can use this rate of increase in luminosity in order to determine the age of the star. This method only works for calculating stellar age on the main sequence, because in advanced evolutionary stages of the star, such as the red giant stage, the standard relationship for the determination of age no longer holds.

However, when one can observe a red giant star with a known mass, one can calculate the main-sequence lifetime,[4] and thus the minimum age of star is known given that it is in an advanced stage of its evolution. As the star spends only about 1% of its total lifetime as a red giant,[5] this is an accurate method of determining age.

Stellar age estimation of stars

Various properties of stars can also be used to determine their age. For example, the Eta Carinae system is emitting large quantities of gas and dust. These enormous outbursts can be used to infer that the star system is nearing the end of its life, and will explode as a supernova within a relatively short period of astronomical time.[6]

Very large stars like VY Canis Majoris, one of the largest stars known, together with Mu Cephei, Betelgeuse and UY Scuti all have radii larger than that of the average orbital radius of Jupiter in the Solar System, thus showing that they are in extremely late evolutionary stages.[7] Betelgeuse in particular is expected to die in a supernova explosion within the next million years.[8]

As well as the scenarios of supermassive stars violently casting off their outer layers before their deaths, other examples can be found of the properties of stars which illustrate their age.

For example, Cepheid variables have a characteristic pattern in their lightcurves, the rate of repetition of which is dependent on the luminosity of the star.[9]

Since Cepheid variables are a relatively short evolutionary stage in the lifecycle of stars, and knowing the mass of the star allows for the star to be tracked in its evolutionary path, one can estimate the age of the Cepheid variable.

Exceptional stellar properties which allow for an estimation of age are not confined to advanced evolutionary stages. When a roughly solar-mass star exhibitis T Tauri variability, astronomers can locate the age of the star as being before the beginning of the main sequence phase of the star’s life.[10]

Additionally, more massive pre-main-sequence stars could be Herbig Ae/Be stars.[11] If a red dwarf star is emitting immense stellar flares and x-rays, the star can be calculated to be in an early stage of its main-sequence lifetime, after which it will become less variable and become stable.[12]

Membership in a star cluster or system

Membership in a star cluster or star system permits an assignment of rough ages to a large number of stars present within.

When one can determine the age of stars through other methods, such as the ones listed above, one can identify the age of all of the bodies in a system.[13] This is especially useful in clusters of stars which exhibit a large amount of variety in their stellar masses, evolutionary stages, and classifications.

While not entirely independent of the properties of the stars in the cluster, system, or other reasonably-sized association of stars, an astronomer would only need a representative sample of stars to determine the age of the cluster, rather than painstakingly finding the age of every star in the cluster through other properties.

In addition, knowing the age of one member of a star system can help determine the age of that system. In a star system, stars almost always form at the same time as each other, and given the age of one star, the age of all of the others can be known.[14]

However, this method does not work for galaxies. These units are much larger, and are not merely a one-off creation of stars which allows their age to be determined in this fashion. The creation of stars in a galaxy takes place over billions of years,[15] even though star production may long since have ceased (see elliptical galaxy).

The oldest stars in a galaxy can only set a minimum age for the galaxy (when star formation began) but by no means determine the actual age.[16]

Presence of a protoplanetary disk

Along with other factors, the presence of a protoplanetary disk sets a maximum limit on the age of stars. Stars with protoplanetary disks are typically young, having moved onto the main sequence only a relatively short time ago.[17]

Over time, this disk would coalesce to form planets, with leftover material being deposited into various asteroid belts and other similar locations. However, the presence of pulsar planets complicates this method as a determinant of age.

Gyrochronology

Gyro-chronology is a method used to determine the age of field stars by measuring their rotation rate, and then comparing this rate with the rotation rate of the Sun, which serves as a precalibrated clock for this measurement.[18]

This method has been seen as a more accurate method for the determination of stellar ages than other methods for field stars.[18]

https://en.wikipedia.org/wiki/Stellar_age_estimation

2 posted on 11/06/2018 11:51:14 AM PST by ETL (Obama-Hillary, REAL Russia collusion! Uranium-One Deal, Missile Defense, Iran Deal, Nukes: Click ETL)
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To: All
Image result for keith richards jagger aging

Beat you all to it!!!

3 posted on 11/06/2018 11:51:49 AM PST by ETL (Obama-Hillary, REAL Russia collusion! Uranium-One Deal, Missile Defense, Iran Deal, Nukes: Click ETL)
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To: ETL

Keith May look old, but he hasn’t aged a day in 40 years.


4 posted on 11/06/2018 11:59:01 AM PST by Moonman62 (Give a man a fish and he'll be a Democrat. Teach a man to fish and he'll be a responsible citizen.)
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To: ETL

With all that helium, you’d probably talk funny on them.


5 posted on 11/06/2018 12:00:14 PM PST by Larry Lucido
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To: ETL

Indeed, it is the new record holder for the star with the smallest complement of heavy elements — it has about the same heavy element content as the planet Mercury. In contrast, our Sun is generations down that line and has a heavy element content equal to 14 Jupiters.

...

That sentence can easily be misinterpreted. They should give percentages instead.


6 posted on 11/06/2018 12:00:29 PM PST by Moonman62 (Give a man a fish and he'll be a Democrat. Teach a man to fish and he'll be a responsible citizen.)
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To: KevinDavis; annie laurie; Knitting A Conundrum; Viking2002; Ernest_at_the_Beach; Mmogamer; ...
Thanks ETL. Keith Richards: "Glad to be here, glad to be anywhere."
 
X-Planets
· join · view topics · view or post blog · bookmark · post new topic · subscribe ·
Google news searches: exoplanet · exosolar · extrasolar ·

7 posted on 11/06/2018 12:07:30 PM PST by SunkenCiv (and btw -- https://www.gofundme.com/for-rotator-cuff-repair-surgery)
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To: ETL

Kirk Douglas?.......................


8 posted on 11/06/2018 12:10:33 PM PST by Red Badger (FNo-platform us all you want. Ban us all you want. Smear us all you want. You canÂ’t stop an idea...)
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To: SunkenCiv

9 posted on 11/06/2018 12:11:45 PM PST by Red Badger (FNo-platform us all you want. Ban us all you want. Smear us all you want. You canÂ’t stop an idea...)
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To: Moonman62
gifs website
10 posted on 11/06/2018 12:12:41 PM PST by ETL (Obama-Hillary, REAL Russia collusion! Uranium-One Deal, Missile Defense, Iran Deal, Nukes: Click ETL)
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To: ETL

No fair excluding black holes and Neutron Stars.


11 posted on 11/06/2018 12:12:47 PM PST by DungeonMaster (Vote your bible.)
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To: ETL

I read somewhere recently that the vast majority of star systems are binary. Single stars are the exception.


12 posted on 11/06/2018 12:16:01 PM PST by fwdude (Forget the Catechism, the RCC's real doctrine is what they allow with impunity.)
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To: Moonman62
They tried to hard for an analogy, just created an odd measuring system.

He must assume everyone knows the metal content of the planets in our solar system.

BTW, Jupiter has a metallic HYDROGEN core just to further confound the system.

Glad someone else noticed.

13 posted on 11/06/2018 12:17:06 PM PST by Aevery_Freeman (An enemy invader does not become a citizen just because he breached the ramparts!)
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To: Moonman62

I have no idea what that sentence means.


14 posted on 11/06/2018 12:19:30 PM PST by bagman
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To: ETL
"The Universe’s first stars after the Big Bang would have consisted entirely of elements like hydrogen, helium, and small amounts of lithium. Those stars then produced elements heavier than helium in their cores and seeded the Universe with them when they exploded as supernovae."

Okay. Now can someone please explain in layman's terms how atoms like hydrogen, helium, and lithium change into new atoms? What's the process? And how do we know this other than a physicist calculations on a white board? How does it happen?

15 posted on 11/06/2018 1:00:13 PM PST by A Navy Vet (I'm not Islamophobic - I'm Islamonauseous. Plus LGBTQxyz nauseous.)
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To: fwdude
I read somewhere recently that the vast majority of star systems are binary. Single stars are the exception.

Supposedly true.

16 posted on 11/06/2018 1:06:16 PM PST by ETL (Obama-Hillary, REAL Russia collusion! Uranium-One Deal, Missile Defense, Iran Deal, Nukes: Click ETL)
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To: A Navy Vet
While I'm at it ... what is gravity? I'm not asking for measurable formulas according to mass...I'm asking what it is? We know that electro-magnetism consists of waves of energy. We know the light spectrum consists of photons. What does gravity consist of?...

Anyone?

17 posted on 11/06/2018 1:11:04 PM PST by A Navy Vet (I'm not Islamophobic - I'm Islamonauseous. Plus LGBTQxyz nauseous.)
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To: A Navy Vet

And while I’m at it, I read some time back that there is no such thing as mass. It is supposedly concentrated energy. Was that proven correct?


18 posted on 11/06/2018 1:13:27 PM PST by A Navy Vet (I'm not Islamophobic - I'm Islamonauseous. Plus LGBTQxyz nauseous.)
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To: A Navy Vet
While I'm at it ... what is gravity? I'm not asking for measurable formulas according to mass...I'm asking what it is?

The result of some still very mysterious interaction between mass and "space-time".

According to Einstein's General Relativity (E=mc^2), mass and energy are "equivalent". Perhaps, somehow, matter/mass zaps energy from space, thereby creating a "well" of negative pressure.

See "Casimir Effect"...

19 posted on 11/06/2018 1:17:36 PM PST by ETL (Obama-Hillary, REAL Russia collusion! Uranium-One Deal, Missile Defense, Iran Deal, Nukes: Click ETL)
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To: A Navy Vet

The Casimir effect

The Casimir effect is a small attractive force that acts between two close parallel uncharged conducting plates. It is due to quantum vacuum fluctuations of the electromagnetic field.

The effect was predicted by the Dutch physicist Hendrick Casimir in 1948. According to the quantum theory, the vacuum contains virtual particles which are in a continuous state of fluctuation (see physics FAQ article on virtual particles).

Casimir realized that between two plates, only those virtual photons whose wavelengths fit a whole number of times into the gap should be counted when calculating the vacuum energy. The energy density decreases as the plates are moved closer, which implies that there is a small force drawing them together.

http://math.ucr.edu/home/baez/physics/Quantum/casimir.html


20 posted on 11/06/2018 1:18:54 PM PST by ETL (Obama-Hillary, REAL Russia collusion! Uranium-One Deal, Missile Defense, Iran Deal, Nukes: Click ETL)
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