Hertzsprung–Russell diagram. An HR diagram showing many well known stars in the Milky Way galaxy. The Hertzsprung–Russell diagram is a scatter graph of stars showing the relationship between the stars' absolute magnitudes or luminosities versus their spectral types or classifications and effective temperatures. Hertzsprung–Russell diagrams are not maps of the locations of the stars.
Rather, they plot each star on a graph measuring the star's absolute magnitude (brightness) against its temperature (color). Hertzsprung–Russell diagrams are also referred to by the abbreviation H–R diagram or HRD. The diagram was created circa 1910 by Ejnar Hertzsprung and Henry Norris Russell and represents a major step towards an understanding of stellar evolution or "the lives of stars".
Historical background[edit] Forms of diagram[edit] There are several forms of the Hertzsprung–Russell diagram, and the nomenclature is not very well defined. Interpretation[edit] Diagram's role in the development of stellar physics[edit] See also[edit] V.massive black holes already existed - 750 mil yrs after BB. Scientists discovered the universe’s earliest black holes and, in the process, added support to a theory that the cosmological objects developed in tandem with their host galaxies.
Black holes occur when stars implode, creating a gravitation collapse that collects and compresses mass in such a way that no light waves can escape. Scientists have sought for decades to determine how they happen and what attributes they carry. The most-recent data came from a study of 250 galaxies detected by the Hubble Space Telescope, compared with signals gathered by the orbiting Chandra X-Ray Observatory. The black holes found are the furthest detected from Earth, and appear as they existed 13 billion years ago, just after the Big Bang that scientists believe began the universe, according to a report today in the journal Nature.
They have a symbiotic relationship with galaxies, the researchers said, feeding on the gas and dust they create. Stacking Images. Astronomers discover earliest black holes at dawn of universe. Astronomers have been peering farther and farther into space, and back in time, using the world's most powerful telescopes to detect galaxies billions of light years away that existed when the universe was just a fraction of its current age. But detecting the giant black holes thought to lurk at the centers of those galaxies has proven much more difficult. Now a team of astronomers has discovered the earliest black holes ever detected, despite the fact that they are hidden from view by their host galaxies. They also measured the average growth rate of the black holes and discovered that they grow and evolve in tandem with their galaxies -- something that astronomers had observed locally but which they knew little about when it came to the early, distant universe.
"This finding tells us there is a symbiotic relationship between black holes and their galaxies that has existed since the dawn of time," said Kevin Schawinski, a Yale astronomer who contributed to the discovery. Hungry Black Holes Lurk at Edge of the Universe. 13 billion light-years away, at the very edge of our observable universe, supermassive black holes lurk inside their galactic hosts, feeding. As the light took 13 billion years to reach us, these black holes actually evolved when the Universe was only a fraction of the age it is now — precisely 13.75 billion years old. WIDE ANGLE: Black Holes, Big and Small This new finding comes from the analysis of Chandra X-Ray Observatory data, where astronomers “stacked” images of 250 distant candidate galaxies as previously spotted by the Hubble Space Telescope.
The stacking process allowed extremely faint X-ray emissions from the centers of the galaxies to multiply, highlighting the location of the black holes living in their cores, feeding off dust, gas and unfortunate stars. This is a significant finding as black holes are known to reside inside local (young) galaxies like our own, but little was known about ancient galaxies.
The team could only detect the most powerful X-rays emitted, however. Most distant black holes ever found reveal secrets - Technology & Science. The new study used images from the Chandra X-Ray Observatory, a space telescope that orbits the Earth, to measure the growth rates of the black holes at the centre of galaxies that existed as early as 700 million years after the Big Bang, such as the black hole shown in this artist's drawing. (A. Hobart/CXC/NASA) Black holes further away from Earth than any ever found before have given astronomers a peek at how galaxies were evolving 13 billion years ago — less than a billion years after the Big Bang. "We're really looking at first baby growth spurts of the black holes that live at the centre of galaxies today, including our own Milky Way," said Kevin Schawinski, one of the five co-authors of the study published Wednesday in Nature.
Schawinski, an astrophysicist at Yale University, noted that the Milky Way's black hole was formed at about the same time as the black holes observed in the study, and likely went through a very similar infancy. The Big Bang Lighting up the Dark Ages. Most Dangerous Places (The Universe 1) part 48 of 60. How the Sun Shines.
By John N. Bahcall* What makes the sun shine? How does the sun produce the vast amount of energy necessary to support life on earth? These questions challenged scientists for a hundred and fifty years, beginning in the middle of the nineteenth century. Theoretical physicists battled geologists and evolutionary biologists in a heated controversy over who had the correct answer. Why was there so much fuss about this scientific puzzle? The sun's rays are the ultimate source of almost every motion which takes place on the surface of the earth. In this essay, we shall review from an historical perspective the development of our understanding of how the sun (the nearest star) shines, beginning in the following section with the nineteenth-century controversy over the age of the sun.
The Age of the Sun How old is the sun? The older the sun is, the greater the total amount of radiated solar energy. Conflicting Estimates of the Solar Age Who Was Right? What was wrong with Kelvin's analysis? F.W. Youngest millisecond pulsar... Millisecond pulsar in spin mode. The gamma radiation of a rapidly rotating neutron star casts doubt on the models of the origin of such objects November 03, 2011 Astronomers have tracked down the first gamma-ray pulsar in a globular cluster of stars. It is around 27,000 light years away and thus also holds the distance record in this class of objects.
Moreover, its high luminosity indicates that J1823-3021A is the youngest millisecond pulsar found to date, and that its magnetic field is much stronger than theoretically predicted. This therefore suggests the existence of a new population of such extreme objects. Zoom Image The NGC 6624 globular cluster in the Sagittarius constellation. The NGC 6624 globular cluster in the Sagittarius constellation. The NGC 6624 globular cluster in the Sagittarius constellation. . © NASA/ESA/I. When the nuclear fuel in the core of a massive star is spent, the star collapses and releases so much energy in the process that it briefly radiates a billion times brighter than before. . © P. 'Zombie' stars.
"Zombie" stars that explode like bombs as they die, only to revive by sucking matter out of other stars. According to an astrophysicist at UC Santa Barbara, this isn't the plot for the latest 3D blockbuster movie. Instead, it's something that happens every day in the universe - something that can be used to measure dark energy. This special category of stars, known as Type Ia supernovae, help to probe the mystery of dark energy, which scientists believe is related to the expansion of the universe. Andy Howell, adjunct professor of physics at UCSB and staff scientist at Las Cumbres Observatory Global Telescope (LCOGT), wrote a review article about this topic, published recently in Nature Communications. LCOGT, a privately funded global network of telescopes, works closely with UCSB. Supernovae are stars that have been observed since 1054 A.D., when an exploding star formed the crab nebula, a supernova remnant.
"That's what our sun will be at the end of its life," he said. “Impossible” Star Exists in Cosmic Forbidden Zone. Want to stay on top of all the space news? Follow @universetoday on Twitter This ancient star, in the constellation of Leo (The Lion), is called SDSS J102915+172927 and has been found to have the lowest amount of elements heavier than helium of all stars yet studied. It has a mass smaller than that of the Sun and is probably more than 13 billion years old.
Credit: ESO/Digitized Sky Survey 2 Astronomers say a newly found star should not exist and is in the “forbidden zone” of a widely accepted theory of star formation. The star, called SDSS J102915+172927, is composed almost entirely of hydrogen and helium, with only remarkably small amounts of other chemical elements in it. And how should this star be classified? The team found the star with the X-shooter and UVES instruments on the Very Large Telescope.
The prevailing theory is that hydrogen and helium were created shortly after the Big Bang, together with some lithium, while almost all other elements were formed later in stars. The star that should not exist. (PhysOrg.com) -- A team of European astronomers has used ESO’s Very Large Telescope (VLT) to track down a star in the Milky Way that many thought was impossible. They discovered that this star is composed almost entirely of hydrogen and helium, with only remarkably small amounts of other chemical elements in it. This intriguing composition places it in the "forbidden zone" of a widely accepted theory of star formation, meaning that it should never have come into existence in the first place. The results will appear in the 1 September 2011 issue of the journal Nature. A faint star in the constellation of Leo (The Lion), called SDSS J102915+172927, has been found to have the lowest amount of elements heavier than helium (what astronomers call “metals”) of all stars yet studied.
It has a mass smaller than that of the Sun and is probably more than 13 billion years old. The team analysed the properties of the star using the X-shooter and UVES instruments on the VLT. AAVSO (AAVSO) sur Twitter. AAVSO | American Association of Variable Star Observers. So you think you're big? A supermassive star, all alone.
A visible/infrared composite view of the Tarantula, with VFTS 682 at its centre. (Image: ESO/M. -R. Cioni/VISTA Magellanic Cloud survey. Acknowledgment: Cambridge Astronomical Survey Unit) The Tarantula Nebula is a gift that keeps on giving – if you’re into really massive stars, that is. It makes for a pretty picture, sure, but Tarantula, in our little galactic sibling the Large Magellanic Cloud at a distance of 170,000 lightyears (50 kpc), is the largest region of ionised hydrogen (HII) in the entire Local Group of galaxies. Some of the region’s clusters contain the most massive stars we know today.
The most massive stars form almost exclusively in clusters, as the clouds they form out of have to be so massive that many smaller stars are inevitably born in the process. Some scientists even propose that the combined winds from supermassive clusters like R136 could even be responsible for blasting heavy elements out of their galaxies entirely, into the intergalactic medium. References.
Quark Stars. Star Types ☆ Team Curated.