#Messier_object

[phonemantra-blog]

The research team studied the planetary nebula's central star in the star cluster, determining that it had lost 70% of its mass over its lifetime. It also turned out that the star has an unusual chemical composition and does not contain hydrogen. Stars like our Sun end their lives as white dwarfs. Some of them are surrounded by a planetary nebula, consisting of gas ejected by a dying star just before the outburst. An international research team led by Professor Klaus Werner from the Institute of Astronomy and Astrophysics at the University of Tübingen studied the central star of a planetary nebula located in an open star cluster. Scientists were able to accurately determine the mass that the central star lost during its life. There are more than a thousand open star clusters in our Galaxy. Each of them includes up to several thousand stars that were formed from a dense cloud of gas and dust. “The stars in the cluster are of the same age, and this is of particular importance for astrophysics,” says Klaus Werner. They differ only in their mass. “The greater the mass of a star, the faster it consumes its nuclear fuel, burning hydrogen into helium. So the life of a large star is shorter and it turns into a white dwarf faster,” he explains. [caption id="attachment_68877" align="aligncenter" width="780"] nebula Messier 37[/caption] Observation of a star cluster shows the development of stars of different masses at the same age. “In astronomy, star clusters can be used as a kind of laboratory where we can test how correct our theories of stellar development are. One of the most uncertain aspects of the theory of stellar development is how much matter a star loses during its life. Stars like our Sun lose almost half their mass by the time they become white dwarfs. Stars eight times heavier than the Sun lose about 80% of their mass,” says the astrophysicist. The mass of white dwarfs in star clusters can be directly related to their mass at birth. Data on very young white dwarfs is especially valuable because they are the central stars of planetary nebulae. But none of their central stars in such nebulae have been studied before because they are all very distant and dim. The research team pointed one of the world's largest telescopes, the ten-meter GRANTECAN telescope, at the central star in the Messier 37 cluster and analyzed its spectrum. They were able to determine the star's mass to be 0.85 solar masses, meaning an original mass of 2.8 solar masses. How the central star of the planetary nebula Messier 37 survived the loss of 70% of its mass “The star thus lost 70% of its matter during its lifetime,” explains Werner. Another feature is its special chemical composition. There is no longer any hydrogen left on its surface. This points to an unusual event in its recent past - a short-term burst of nuclear reactions. The ability to accurately determine the start-to-end mass relationship of a star is of fundamental importance in astrophysics. It determines whether a star becomes a white dwarf, becomes a neutron star during a supernova, or becomes a black hole at the end of its life. From the ejected matter at the moment of “rebirth” of the star, new generations of stars are formed, enriched with heavy elements as products of nuclear reactions. The chemical evolution of galaxies, and ultimately the entire Universe, depends on this.

[apod]

2020 January 19

M1: The Incredible Expanding Crab Nebula Video Credit & Copyright: Detlef Hartmann

Explanation: Are your eyes good enough to see the Crab Nebula expand? The Crab Nebula is cataloged as M1, the first on Charles Messier's famous list of things which are not comets. In fact, the Crab is now known to be a supernova remnant, an expanding cloud of debris from the explosion of a massive star. The violent birth of the Crab was witnessed by astronomers in the year 1054. Roughly 10 light-years across today, the nebula is still expanding at a rate of over 1,000 kilometers per second. Over the past decade, its expansion has been documented in this stunning time-lapse movie. In each year from 2008 to 2017, an image was produced with the same telescope and camera from a remote observatory in Austria. Combined in the time-lapse movie, the 10 images represent 32 hours of total integration time. The sharp, processed frames even reveal the dynamic energetic emission within the incredible expanding Crab. The Crab Nebula lies about 6,500 light-years away in the constellation Taurus.

∞ Source: apod.nasa.gov/apod/ap200119.html

[wigmund]

From SpaceTelescope.Org Picture of the Week; October 8, 2018:

Rings Upon Rings

This image from the NASA/ESA Hubble Space Telescope reveals a spiral galaxy named Messier 95 (also known as M95 or NGC 3351). Located about 35 million light-years away in the constellation of Leo (The Lion), this swirling spiral was discovered by astronomer Pierre Méchain in 1781, and cataloged by French astronomer Charles Messier just four days later. Messier was primarily a comet hunter, and was often left frustrated by objects in the sky that resembled comets but turned out not to be. To help other astronomers avoid confusing these objects in the future, he created his famous catalog of Messier objects.

Most definitely not a comet, Messier 95 is actually a barred spiral galaxy. The galaxy has a bar cutting through its center, surrounded by an inner ring currently forming new stars. Also our own Milky Way is a barred spiral.

As well as hosting this stellar nursery, Messier 95 is a known host of the dramatic and explosive final stages in the lives of massive stars: supernovae. In March 2016 a spectacular supernova named SN 2012aw was observed in the outer regions of one of Messier 95’s spiral arms. Once the light from the supernova had faded, astronomers were able to compare observations of the region before and after the explosion to find out which star had “disappeared” — the progenitor star. In this case, the star was an especially huge red supergiant up to 26 times more massive than the Sun.

Credit: ESA/Hubble & NASA

[apod]

2017 June 14

M89: Elliptical Galaxy with Outer Shells and Plumes Image Credit & Copyright: Mark Hanson

Explanation: Can you see them? This famous Messier object M89, a seemingly simple elliptical galaxy, is surrounded by faint shells and plumes. The cause of the shells is currently unknown, but possibly tidal tails related to debris left over from absorbing numerous small galaxies in the past billion years. Alternatively the shells may be like ripples in a pond, where a recent collision with another large galaxy created density waves that ripple through this galactic giant. Regardless of the actual cause, the featured image highlights the increasing consensus that at least some elliptical galaxies have formed in the recent past, and that the outer halos of most large galaxies are not really smooth but have complexities induced by frequent interactions with -- and accretions of -- smaller nearby galaxies. The halo of our own Milky Way Galaxy is one example of such unexpected complexity. M89 is a member of the nearby Virgo cluster of galaxies which lies about 50 million light years distant.

∞ Source: apod.nasa.gov/apod/ap170614.html