From Manu Garcia: “RMC 136a star-forming region”


Manu Garcia, a friend from IAC.

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Discover giant star of 300 solar masses.

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RCM 136a

July 21, 2010

Using a combination of instruments at the Very Large Telescope of ESO astronomers discovered the most massive stars to date, one weighing at birth more than 300 times the Sun’s mass, twice the currently accepted limit of 150 solar masses . The existence of such monsters million times more luminous than the Sun, losing weight through very powerful winds could provide an answer to the mystery of “how massive can stars be?”.

ESO/VLT at Cerro Paranal, with an elevation of 2,635 metres (8,645 ft) above sea level

A team of astronomers led by Paul Crowther, professor of astrophysics at the University of Sheffield, used the Very Large Telescope (VLT) and file information from the NASA/ESA Hubble Space Telescope to study in detail two young clusters stars: NGC 3603 and RMC 136a .

NASA/ESA Hubble Telescope

NGC 3603 is a star factory where stars form intensely in the vast clouds of gas and dust of the nebula, located 22,000 from the Sun light years. RMC 136a (more commonly known as R136 ) is another cluster of young, massive hot stars located inside the Tarantula Nebula in one of our neighboring galaxies, the Large Magellanic Cloud, 165,000 light-years away.

Large Magellanic Cloud. Adrian Pingstone December 2003

The team found several stars with surface temperatures over 40,000 degrees: about seven times hotter than our Sun, several tens of times larger and brighter than it several million times. Comparisons with models indicate that several of these stars were born with masses in excess of 150 solar masses. Star R136a1 , found in the cluster R136 , is the most massive star ever discovered with a current mass of 265 solar masses and a birth weight of about 320 times the mass of the sun.

In NGC 3603 astronomers could also directly measure the masses of two stars belong to a double star system [1], as a validation of the models used. A1, B and C stars in this cluster have estimated birth above or close to 150 solar masses masses.

Very massive stars produce very powerful flows. “Unlike humans, these stars are born heavy and lose weight as they age , ” says Paul Crowther. “Having a little over a million years, the most extreme star R136a1 is in a ‘middle – aged’ and has undergone an intense weight loss, shedding during that period of time a fifth of its initial mass or more 50 solar masses “.

If R136a1 replaced the Sun in our Solar System, the Sun would surpass much as the Sun currently exceeds the full moon. “Its high mass would reduce the length of the Earth year to three weeks and would bathe the Earth in incredibly intense ultraviolet radiation, making life on our planet impossible , ” says Raphael Hirschi from Keele University and part of the team.

Weighty these stars are extremely rare and are formed solely within the densest star clusters. Individual stars, as has now been achieved for the first time requires special resolving power of the VLT’s infrared instruments [2].

The team also estimated the maximum possible mass for the stars within these clusters and the relative number of these most massive stars. “The smallest stars are limited to more than about 80 times more than Jupiter, below which they are ‘failed stars’ or brown dwarfs,” says team member Olivier Schnurr from the Astrophysikalisches Institut Potsdam. “Our new finding supports the previous view that there is also an upper limit that determines how large can become the stars, although this limit was increased by a factor of two, to about 300 solar masses.”

Within R136 , only four stars weighed at birth more than 150 solar masses, yet they are responsible for nearly half of the wind and radiation power of the entire cluster, comprising approximately 100,000 stars in total. R136a1 alone energises its surroundings by a factor of more than 50 compared to the mass of the Orion Nebula, the zone of massive star formation closest to Earth.

Understand how very massive stars form is quite difficult because of their short lives and powerful winds, therefore, to identify cases as extreme as that of R136a1 further it increases the challenge for theorists. “Or were born so big or smaller stars merged together to produce them, ” explains Crowther.

Stars between about 8 and 150 solar masses explode at the end of their short lives as supernovae, leaving behind exotic remnants, such as neutron stars or black holes. Once established the existence of stars weighing between 150 and 300 solar masses, the discoveries made by astronomers increase the chances that there are “pairs of unstable supernovae” exceptionally bright, it is completely annihilated without a trace, spreading up to ten solar masses iron around. A few candidates for such explosions have already been proposed in recent years.

R136a1 is not only the most massive star ever found, but also the brightest, some 10 million times brighter than the sun. “Because of the rarity of these monsters, I think it is unlikely that this new record will be exceeded soon , “he concludes Crowther.

Notes

[1] The star A1 in NGC 3603 is a double star with an orbital period of 3.77 days. The two stars in the system have 120 and 92 times the mass of Sol respectively, which means that when formed as stars weighing 148 and 106 solar masses respectively.

[2] The team used the SINFONI, ISAAC and MAD instruments, all installed on the Very Large Telescope at Paranal, Chile.

Additional Information

This work is presented in an article published in the Monthly Notices of the Royal Astronomical Society ( “The R136 star cluster hosts Whose Several stars Greatly Exceed the single masses accepted 150 Msun stellar mass limit”, by P. Crowther and his team).

The team is composed of Paul A. Crowther, Richard J. Parker and Simon P. Goodwin (University of Sheffield, UK), Olivier Schnurr (University of Sheffield and Astrophysikalisches Institut Potsdam, Germany), Raphael Hirschi (Keele University, UK ) and Norhasliza Yusof and Hasan Abu Kassim (University of Malaya, Malaysia).

ESO, the European Southern Observatory, is the foremost intergovernmental astronomy organization in Europe and the most productive astronomical observatory in the world. It is supported by 14 countries: Austria, Belgium, Denmark, Spain, Finland, France, Holland, Italy, Portugal, the United Kingdom, Czech Republic, Sweden and Switzerland. ESO carries out an ambitious program focused on the design, construction and operation of powerful ground-based observing that allow astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organizing cooperation in astronomical research. ESO operates three unique observing sites world-class Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world’s most advanced optical observatory. ESO is the European partner of a revolutionary astronomical telescope ALMA, the largest astronomical project. ESO is currently planning a European Extremely Large Telescope, the E-ELT, optical and close to 42 meters in diameter, which will become “the world’s biggest eye on the sky” infrared telescope.

The input image.

Using a combination of instruments at the Very Large Telescope of ESO astronomers discovered the most massive stars to date, some weighing at birth more than 300 times the Sun’s mass, twice the currently accepted limit of 150 solar masses. The most extreme of these stars was found in the cluster RMC 136a (commonly called R136). The name of R136a1, this star has a current mass of 265 times that of the sun. With just over a million years, R136a1 is middle-aged now and has followed an intense program of weight loss, shedding a fifth of its initial mass during that period of time, or more than fifty solar masses. It also has the largest known luminosity, about 10 million times greater than Sun’s luminosity.

R136 is a cluster of hot, young stars and massive located inside the Tarantula Nebula, in one of the neighboring galaxies of the Milky Way, the Large Magellanic Cloud, a distance of 165,000 light years. R136 contains many stars that on a scale equivalent to the distance between the Sun and its nearest star can be found tens of thousands of stars. Hundreds of these stars are so incredibly bright that if we were sitting in a (hypothetical) planet in the middle of the cluster, never darken the sky.

This montage shows a photograph of the Tarantula Nebula seen with the Wide Field Imager on the MPG / ESO telescope 2.2m (left), with the Very Large Telescope (center), along with a new picture of the cluster obtained R136 with MAD adaptive optics instrument Very Large Telescope (right). The latter provides unique details of the stellar content of the cluster.

Credit:
ESO / P. Crowther / CJ Evans

For more information here

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Using a combination of instruments at the Very Large Telescope of ESO astronomers discovered the most massive stars to date, some weighing at birth more than 300 times the Sun’s mass, twice the currently accepted limit of 150 solar masses. This artist ‘s impression shows the relative sizes of young stars, from the smallest “red dwarfs” calls weighing about 0.1 solar masses, through the “yellow dwarf” middle mass as the Sun and the “blue dwarf” stars mass they are weighing 8 times more than the Sun, reaching the 300 solar mass star recently discovered, called R136a1.

Credit:
ESO / M. Kornmesser

Author’s note:
Red Dwarf – Red Dwarf.
Yellow dwarf (like Sun) – Yellow Dwarf (like the Sun)
Blue dwarf – blue dwarf.
R136a1 – name star to study.

See the full article here .

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