📰 A completely isolated dwarf galaxy subject to an intriguing gas loss


WLM galaxy. Yang et al

Isolated dwarf galaxies appear to be remnants of the early universe and are not intended to interact with their environment. Observing one of them, an international team led by scientists from the CNRS (The National Center for Scientific Research, better known by its acronym CNRS, is the largest …) and theParis Observatory (The Paris Observatory was born from the project, in 1667, to create an astronomical observatory …) – PSL found it strong interaction (An interaction is an exchange of information, affect or energy between two agents within …) with the intergalactic medium, while the latter is supposed to be very scarce. Doing theobject (In general, the word object (from the Latin objectum, 1361) designates an entity defined in …) from a letter published in the journal Astronomy and Astrophysics on April 27, 2022, this discovery alters the understanding of the formation and evolution of dwarf galaxies and opens a new rural area (A field corresponds to a notion of defined space 🙂 of questions.

Dwarf galaxies are affected by the same evolutionary processes that work in large galaxies such as Milky Way (The Milky Way (also called “our galaxy”, or sometimes …) or he galaxy (Galaxies is a French quarterly magazine dedicated to science fiction. With …) of Andromeda. Less bright and less massive than their older sisters, they are especially sensitive to the environmental mechanisms caused by the presence of a galaxy (A galaxy is, in cosmology, a set of stars, gas, dust and …) giant (A giant star is a star of luminosity class II or III. In …) in theirs neighborhood (The notion of neighborhood corresponds to an axiomatic approach equivalent to that of …). In this case, they may be subject to the effects of gravitational tides or the pressure (Pressure is a fundamental physical notion. You can think of it as an informed force …) dynamic (The word dynamic is often used to designate or describe what is related to movement. This …) caused by the surrounding gaseous medium. To determine the significance of these effects, astronomers can compare the differences between the populations of dwarf galaxies: with the so-called “satellites” on the one hand and the so-called “isolated” on the other.

WLM is considered the archetype of a dwarf galaxy (A dwarf galaxy is a small galaxy composed of about 10 billion stars, a number …) isolated. It was discovered in 1909 by Max Wolf (Maximilian Franz Joseph Cornelius Wolf (June 21, 1863 – October 3, 1932 …), later confirmed by Knut Lundmark and Philibert Melotte (hence its name “WLM” after the initials of its co-discoverers). It is equidistant between the Milky Way and the M31, almost 3 million light-years away. It would have formed in isolation total (Total is the quality of the complete, without exception. From the accounting point of view, in …), without any external disturbance. So its too (The term mass is used to designate two quantities together with one …) of subject matter (Matter is the substance that forms any body that has a tangible reality. It is …) Darkness is considered stable and solidly determined, up to 90 times greater than its baryonic matter, composed of stars and gas (A gas is a set of atoms or molecules very weakly attached and …).

However, recent comments (Observation is the act of closely monitoring the phenomena, without wanting to see them …) performed in radio telescopes (A radio telescope is a specific telescope used in radio astronomy for …) MeerKAT by an international team led by engineer (“The basic job of an engineer is to solve problems in nature …) CNRS at the Observatory of Paris (Paris is a French city, capital of France and capital of the region …) – PSL revealed a strong interaction between WLM and the intergalactic medium. Thehydrogen (Hydrogen is a chemical element with symbol H and atomic number 1.) The galaxy’s neutral is repelled by a dynamic pressure effect caused by its own motion through the intergalactic medium.

From deeper radio observations, scientists have effectively identified four hydrogen-neutral gas clouds extending in the opposite direction to their motion in the WLM. cel (The sky is the Earth’s atmosphere as seen from the planet’s ground.)determined by the data (In information technology (IT), data is an elementary description, often …) recent by Gaia satellite (The Gaia satellite is a European Space Agency (ESA) astrometric mission in front of …) of ESA.

“The four clouds make up 10% of the galaxy’s total neutral hydrogen mass. We also found that there is a space delay between the gas and the WLM stars,” said Roger Ianjamasimanana, a radio astronomer at WLM.University (A university is an institution of higher education whose goal is …) Wheels (Rhodes (in ancient Greek Ῥόδος / Rhódos, modern …)en Africa (With an area of ​​30,221,532 km2 including the islands, …) of South (The south is a cardinal point, opposite the north.). With the discovery of these four gaseous tracks, the team of research (Scientific research first designates all the actions carried out with the aim of …) concludes that WLM gas is expelled from it, due to the dynamic pressure exerted by the surrounding gaseous medium.


Composite image, in optics and radio (To delete), from WLM, an isolated dwarf galaxy equidistant from the Milky Way and the Andromeda Galaxy. Observations with the MeerKAT radio telescope reveal four hydrogen stars in neutral hydrogen (transparent blue) as a result of their turn (In geometry, a displacement is a resemblance that preserves distances and angles …) (represented by the orange arrow): a strange object that is not supposed to interact with the intergalactic environment around it. Yang et al. / Paris Observatory – PSL / CNRS / ESO / NOAO / MeerKAT

This finding comes as a complete surprise to researchers: “The intergalactic medium in which WLM resides is supposed to be almost empty (Void is usually defined as the absence of matter in a space area.), composed of a thin layer of gas. Until now, scientists assumed that such a faint environment could not cause this effect in a galaxy, “said Yanbin Yang, a CNRS engineer at the Paris Observatory – PSL, and the first author of the article.

To study the effect in more detail, the team performed computer simulations. “In our simulations, we also found that the observations can only be explained if the intergalactic medium turns out to be much denser than expected. It seems that we have found a very large and unexpected deposit of matter in the regions between the least denseUniverse (The universe is the sum of all that exists and the laws that govern it.)“, adds the scientific (A scientist is a person who is engaged in the study of one or more sciences and who …).

Another hypothesis would be that the mass of WLM would be much smaller and could even be devoid of dark matter. This would explain how the intergalactic medium, so weak density (The density or relative density of a body is the relationship between its density and the …), may be able to remove WLM, by dynamic pressure. But it would also be a groundbreaking result, because so far it is believed that the mass of galaxies is dominated by this mysterious dark matter.

In summary, the team concludes two scenarios: either these almost “empty” intergalactic regions are not really empty, or the WLM galaxy is deficient in dark matter.

In any case, this study revolutionizes the understanding of dwarf galaxies. In the future, however future (Futures is a science fiction collection from Aurora Editions.) work, will never again be considered completely isolated.

Also read the information on this same topic:
– on the website of the Max Plack Institute of Radio Astronomy
– on the University of Rhodes website

Reference:
The article ‘Evidence of ram-pressure stripping of WLM, the dwarf galaxy far from any large host galaxy’ by Yanbin Yang et al. (2022) is published in a letter from the journal Astronomy & Astrophysics, April 27, 2022. DOI: https://www.aanda.org/10.1051/0004-6361/202243307

International cooperation:
The international team includes scientists from the Paris Observatory – PSL and CNRS, as well as the Institute of Astrophysics of Andalusia (Spain), the University of Rhodes (South Africa), the University of Cape Town. People (The British class of light cruisers took place just before and …) (South Africa), University of Victoria (Canada),University of Montreal (The University of Montreal is one of the four educational institutions …) (Canada), Ouaga University (Burkina Faso), Max-Planck-Institut für Radio astronomy (Radio astronomy is a branch of astronomy that deals with the observation of the sky in …) (Germany) and NRC Herzberg Astronomy and Astrophysics (Canada).

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