Measuring galaxies giant Messier 87

Using ESO's ultra-large VLT telescope, astronomers have succeeded in determining the size of the giant Messier 87 galaxy. They were also surprised to find that the outer part was blown away by some mysterious effect. The galaxy Messier 87 is also in the process of colliding with another giant galaxy in the cluster of galaxies that are powerful.

The new observations that reveal the galaxy's halo to the Messier 87 have been truncated, with a diameter of only about 1 million light-years, much smaller than expected even though it is still three times larger. Surrounding the Milky Way. Outside this area only a few intergalactic stars are observed.

Co-author Ortwin Gerhard said: 'This is an unexpected result. Many research models predict that the halo around Messier 87 must be several times larger than what our observations reveal. Apparently an impact has narrowed the light of Messier 87 beforehand. '

The team used FLAMES - the super-effective spectrophotometer on the ESSO VLT telescope at the Paranal observatory in Chile - to provide accurate predictions of the planetary nebula located on Messier's periphery. 87 and in the intergalactic region in the Virgo galaxy cluster of Messier 87. FLAMES can simultaneously determine the spectrum of many sources, covering a region of the sky the size of the moon.

New results are indeed a great success. Light observed from the planetary nebula in the Virgo Cluster is quite fuzzy, only equivalent to a 30 Watt bulb located at a distance of 6 million km (15 times the distance between the earth and the moon). In addition, planetary nebulae spread a relatively thin layer in the planetary cluster, so even FLAMES's wide field can only see a few parts of the nebula at the same time.

The team member Magda Arnaboldi said: 'FLAMES spectral recorder on the VLT telescope is the most suitable tool for this research'. At a distance of 50 million light-years, the Virgo cluster is the closest galaxy cluster to us. It is located in the constellation Virgo, and is quite young and quite sparse. The planetary cluster consists of hundreds of galaxies of all sizes, from giant elliptical galaxies to simple spiral galaxies like our Milky Way galaxy.

Astronomers have provided some explanations for the detected 'loss' of Messer 87, such as the collapse of dark matter in the planet's cum. It is also possible that another galaxy in the cluster - Messier 84 - has come very close to Messier 87 in the past and disturbed it about 1 billion years ago. Arnaboldi said: 'At this stage, we cannot be sure of any hypothesis. We will need to conduct more observations of other planetary nebulae around Messier 87 '.

But there is one thing astronomers are sure of - Messier 87 and its neighbor Messier 86 are moving toward each other. Gerhard said: 'We can observe them when they are in the stage just before the time when they come together for the first time. The Virgo Cluster is a cluster of galaxies that is extremely powerful. Many factors will continue to work to shape the galaxies in the cluster over a period of one billion years'.

The picture of the Virgo Cluster captured by Chris Mihos and his colleagues with the Burrell Schmidt telescope shows the diffuse light between galaxies belonging to this cluster. North direction on the east and east on the right. The dark spots in the main picture are where the nearby stars have been removed from the image. (Photo: ESO)

The background in the planetary nebula

Planetary Nebula (PNe) is the last spectacular stage in the life of stars like the sun when that star has released all its outer layers into the surrounding space. The name planetary nebula is a remnant of the ancient age: the first observers only used very small telescopes to suggest that some objects are close to us, such as nebulae. Helix is ​​very similar to the plates of giant planets in the solar system. Planetary nebulae have very strong emission paths that make them quite easily detected from a distance, which allows their radial velocity to be accurately determined. Thus planetary nebulae can be used to determine the movement between stars in fainter outer regions of galaxies located far away where velocity determinations are not possible.

Besides planetary nebulae and represent the stars in general. They have a relatively short life (a few tens of thousands of years - just like an astronomical explosion), so scientists can estimate that a star is among the 8000 stars Other suns can be observed as planetary nebulae at a certain moment. So planetary nebulae can provide a unique clue about numbers, star types as well as their movement in fainter outer galaxies but at the same time refuge them. quite large objects. These movements are fossil records of the history of galactic interactions as well as the formation of galaxy clusters.

Astronomers participated in the study

The team includes Michelle Doherty and Magda Arnaboldi (ESO), Payel Das and Ortwin Gerhard (Max-Planck, Garching, Germany), J. Alfonso L. Aguerri (IAC, Tenerife, Spain) , Robin Ciardullo (Pennsylvania State University, USA), John J. Feldmeier (Youngstown University, USA), Kenneth C. Freeman (Stromlo Mountain Observatory, Australia), George H. Jacoby (WIYN Observatory, AZ, USA), and Murante (INAF, Osservatorio Astronomico di Pino Torinese, Italy).

References:
Doherty et al.Edge of M87 halo và sự kiện của Diffuse light trong các Virgo cluster core.Astronomy and Astrophysics, 2009;DOI: 10.1051 / 0004-6361 / 200811532