TAILS OF IONISED GAS IN NGC 4569

Image: The colour image of the galaxy NGC 4569 in the Virgo cluster, obtained with MegaCam at the CFHT. The red filaments at the right of the galaxy show the ionised gas removed by ram pressure. This is about 95% of the gas reservoir of the galaxy needed to feed the formation of new stars Credit: CFHT/Coelum

Messier 90 (also known as M90 and NGC 4569) is a member of the Virgo cluster and one of its largest and brightest spiral galaxies, about 60 million light-years away.

The environment plays a fundamental role in galaxy evolution. In fact, as a consequence of the galaxy's interaction with the intracluster medium in the Virgo Cluster, the galaxy NGC 4569 has lost much of its interstellar medium.

In the paper (Boselli et al. 2013, A&A) the authors analyze the image of NGC 4569 obtained with MegaCam at the CFHT and reveal the presence of a long tails of diffuse ionised gas without any associated stellar component extending from the disc of the galaxy up to ~ 80 kpc. This tail is referred to as ram-pressure stripping. The image also shows a prominent 8 kpc spur of ionised gas associated to the nucleus that spectroscopic data identify as an outflow.

Image: NGC 4569. Credit: NOAO/AURA/NSF.

The gas is ionised within the tail during the stripping process. The lack of star forming regions suggests that mechanisms other than photoionisation are responsible for the excitation of the gas (shocks, heat conduction, magneto hydrodynamic waves).

This analysis indicates that ram pressure stripping is efficient in massive (M_star ~ 30 billion M_sun) galaxies located in intermediate mass (~10¹⁴ M_sun) clusters under formation.

The authors conclude that ram pressure stripping, rather than starvation through nuclear feedback, can be the dominant mechanism responsible for the quenching of the star formation activity of galaxies in high density environments.

Boselli et al. 2013, A&A - Spectacular tails of ionised gas in the Virgo cluster galaxy NGC 4569 (arXiv)
NGC 4569 - (cfht.hawaii.edu)(Wikipedia)

Comments

‘Monster’ Planet Discovery Challenges Formation Theory

Artist’s illustration of a "hot Jupiter". Image Credit: NASA/CXC/M. Weiss A new research presents the discovery of NGTS-1b, a hot-Jupiter transiting an early M-dwarf host in a P~2.6 days orbit discovered as part of the Next Generation Transit Survey (NGTS). The planet has a mass of M~0.8 M(jupiter) making it the most massive planet ever discovered transiting an M-dwarf. NGTS-1b is the third transiting giant planet found around an M-dwarf, reinforcing the notion that close-in gas giants can form and migrate similar to the known population of hot Jupiters around solar type stars. The existence of the 'monster' planet, 'NGTS-1b', challenges theories of planet formation which state that a planet of this size could not be formed around such a small star. According to these theories, small stars can readily form rocky planets but do not gather enough material together to form Jupiter-sized planets. Such massive planets were not thought to exist ar...

CONSTRAINTS ON THE LOCATION OF A POSSIBLE 9TH PLANET

Image: The six most distant known objects in the solar system with orbits exclusively beyond Neptune (magenta) all mysteriously line up in a single direction. Such an orbital alignment can only be maintained by some outside force, Batygin and Brown say. Their paper argues that a planet with 10 times the mass of the earth in a distant eccentric orbit anti-aligned with the other six objects (orange) is required to maintain this configuration. Credit: Caltech The astronomers have noticed some of the dwarf planets and other small, icy objects tend to follow orbits that cluster together. To explain the unusual distribution of these Kuiper Belt objects, several authors have advocated the existence of a superEarth planet in the outer solar system ( planet Nine or planet X ).

ORBITAL PERIODS OF THE PLANETS

For orbital period generally we refer to the sidereal period, that is the temporal cycle that it takes an object to make a full orbit, relative to the stars. This is the orbital period in an inertial (non-rotating) frame of reference (365,25 days for the earth).

SpaceTime

Search This Blog