scholarly journals Group pre-processing versus cluster ram-pressure stripping: the case of ESO156−G029

2019 ◽  
Vol 490 (1) ◽  
pp. L6-L11 ◽  
Author(s):  
Robert Džudžar ◽  
Virginia Kilborn ◽  
Chandrashekar Murugeshan ◽  
Gerhardt Meurer ◽  
Sarah M Sweet ◽  
...  
Keyword(s):  
Rapid Evolution ◽  
Neutral Hydrogen ◽  
Current Data ◽  
Cluster Galaxy ◽  
The Past ◽  
Gas Kinematics ◽  
Ram Pressure ◽  
The Galaxy ◽  
A Minor ◽  
Projected Distance

ABSTRACT We report on observations of ESO156−G029, member of a galaxy group which is positioned at the virial radius of cluster Abell 3193. ESO156−G029 is located ∼1.4 Mpc in projected distance from the brightest cluster galaxy NGC1500. We show that ESO156−G029 has disturbed gas kinematics and a highly asymmetric neutral hydrogen (H i) distribution, which are consequences of group pre-processing, and possibly of ram pressure. Based on the current data we propose a scenario in which ESO156−G029 had a minor gas-rich merger in the past and now starts to experience ram pressure. We infer that the galaxy will undergo rapid evolution once it gets closer to the cluster centre (less than 0.5 Mpc) where ram pressure is strong enough to begin stripping the H i from the galaxy.

scholarly journals The Kinematics of the Magellanic Clouds

1995 ◽  
Vol 166 ◽  
pp. 273-282
Author(s):  
B.E. Westerlund
Keyword(s):  
Galactic Halo ◽  
Neutral Hydrogen ◽  
Magellanic Clouds ◽  
Great Promise ◽  
Common Envelope ◽  
The Past ◽  
Ram Pressure ◽  
Long Time ◽  
Magellanic Stream ◽  
Magellanic System

It is essential for our understanding of the evolution of the Magellanic System, comprising the Large and the Small Magellanic Cloud, the Intercloud or Bridge region and the Magellanic Stream, to know its motions in the past. The Clouds have a common envelope of neutral hydrogen; this indicates that they have been bound to each others for a long time. The Magellanic System moves in the gravitational potential of our Galaxy; it is exposed to ram pressure through its movement in the galactic halo. Both effects ought to be noticeable in their present structure and kinematics. It is generally assumed, but not definitely proven, that the Clouds have been bound to our Galaxy for at least the last 7 Gyr. Most models assume that the Clouds lead the Magellanic Stream. The interaction between the Clouds has influenced their structure and kinematics severely. The effects should be possible to trace in the motions of their stellar and gaseous components as pronounced disturbances. Recent astrometric contributions in this field show a great promise for the future if still higher accuracy can be achieved.

scholarly journals Evidence for ram-pressure stripping in a cluster of galaxies at z = 0.7

2019 ◽  
Vol 631 ◽  
pp. A114 ◽  
Author(s):  
A. Boselli ◽  
B. Epinat ◽  
T. Contini ◽  
V. Abril-Melgarejo ◽  
L. A. Boogaard ◽  
...  
Keyword(s):  
Surface Brightness ◽  
Massive Star ◽  
Observational Evidence ◽  
Star Forming ◽  
Cluster Of Galaxies ◽  
Stellar Component ◽  
Ram Pressure ◽  
The Galaxy ◽  
The Universe ◽  
Projected Distance

Multi-Unit Spectroscopic Explorer (MUSE) observations of the cluster of galaxies CGr32 (M200 ≃ 2 × 1014 M⊙) at z = 0.73 reveal the presence of two massive star-forming galaxies with extended tails of diffuse gas detected in the [O II]λλ3727–3729 Å emission-line doublet. The tails, which have a cometary shape with a typical surface brightness of a few 10−18 erg s−1 cm−2 arcsec−2, extend up to ≃100 kpc (projected distance) from the galaxy discs, and are not associated with any stellar component. All this observational evidence suggests that the gas was removed during a ram-pressure stripping event. This observation is thus the first evidence that dynamical interactions with the intracluster medium were active when the Universe was only half its present age. The density of the gas derived using the observed [O II]λ3729/[O II]λ3726 line ratio implies a very short recombination time, suggesting that a source of ionisation is necessary to keep the gas ionised within the tail.

scholarly journals What Bends Wide-Angle Tailed Radio Sources?

1982 ◽  
Vol 97 ◽  
pp. 45-46
Author(s):  
Jack O. Burns ◽  
Jean A. Eilek ◽  
Frazer N. Owen
Keyword(s):  
Radio Galaxy ◽  
Radio Sources ◽  
Wide Angle ◽  
Velocity Data ◽  
Cluster Galaxy ◽  
Potential Wells ◽  
X Ray ◽  
Ram Pressure ◽  
The Galaxy ◽  
Cd Galaxies

It has been generally assumed that wide-angle tailed (WAT) sources like 3C465 are formed in a manner similar to that of the more strongly bent U-shaped sources such as NGC 1265, i.e., by ram pressure arising from galaxy motion through a dense intracluster medium (ICM). The WAT sources were thought to be less strongly bent because of the smaller ratio of tail plasma flow momentum flux to galaxy velocity. However, as noted recently by Burns (1981), there is a serious discrepancy between the ram pressure model requirements for bending WATs and the dynamics of the associated radio galaxy. To bend the tails, we calculate that the galaxy must typically move at velocities of 0.7–1×103 km s−1 for distances comparable to the length of the radio tails (∼200 kpc for 3C465). This implied galaxy motion is inconsistent with the nature of the massive cD galaxies generally associated with WATs. Cluster galaxy velocity data, X-ray observations, and recent models suggest that these giant galaxies are nearly at rest at the bottoms of cluster potential wells, at most moving ∼200 km s−1 in an oscillatory motion of small amplitude (<0.3 of a core radius, Malumuth, 1981, private communication). Thus it appears that some other mechanism is responsible for bending WAT sources.

Galactic dynamics and DM profile of NGC1380 with ALMA and VLT/MUSE

2019 ◽  
Vol 14 (S353) ◽  
pp. 248-252
Author(s):  
Takafumi Tsukui ◽  
Satoru Iguchi ◽  
Kyoko Onishi
Keyword(s):  
Dark Matter ◽  
Galaxy Evolution ◽  
Neutral Hydrogen ◽  
Hydrogen Gas ◽  
Large Field ◽  
Molecular Gas ◽  
Early Type ◽  
Stellar Kinematics ◽  
Gas Kinematics ◽  
The Galaxy

AbstractIn order to understand the interaction between dark matter and baryonic matter in the galaxy evolution history, it is fundamental to constrain dark matter (DM) distribution in galaxies. However, it is difficult to constrain DM profile in the central region of early type galaxy because of the lack of extended neutral hydrogen gas and the degeneracy between dynamical stellar M/L and DM profile. To resolve this difficulty, we conducted combined analysis of ALMA cold molecular gas kinematics and MUSE stellar kinematics of early type fast rotator galaxy NGC1380. In addition, we used HST image to trace the stellar luminosity distribution. With the help of high resolution of ALMA image and large field of view of MUSE, we derived the central BH mass, stellar bulge, disk and DM profile.

scholarly journals MeerKAT HI commissioning observations of MHONGOOSE galaxy ESO 302-G014

2020 ◽  
Vol 643 ◽  
pp. A147
Author(s):  
W. J. G. de Blok ◽  
E. Athanassoula ◽  
A. Bosma ◽  
F. Combes ◽  
J. English ◽  
...  
Keyword(s):  
Star Formation ◽  
Dwarf Galaxy ◽  
Current Data ◽  
Nearby Galaxy ◽  
Imaging Data ◽  
Ancillary Data ◽  
Neutral Gas ◽  
The Galaxy ◽  
Low Mass ◽  
A Minor

Aims. We present the results of three commissioning H I observations obtained with the MeerKAT radio telescope. These observations make up part of the preparation for the forthcoming MHONGOOSE nearby galaxy survey, which is a MeerKAT large survey project that will study the accretion of gas in galaxies and the link between gas and star formation. Methods. We used the available H I data sets, along with ancillary data at other wavelengths, to study the morphology of the MHONGOOSE sample galaxy, ESO 302-G014, which is a nearby gas-rich dwarf galaxy. Results. We find that ESO 302-G014 has a lopsided, asymmetric outer disc with a low column density. In addition, we find a tail or filament of H I clouds extending away from the galaxy, as well as an isolated H I cloud some 20 kpc to the south of the galaxy. We suggest that these features indicate a minor interaction with a low-mass galaxy. Optical imaging shows a possible dwarf galaxy near the tail, but based on the current data, we cannot confirm any association with ESO 302-G014. Nonetheless, an interaction scenario with some kind of low-mass companion is still supported by the presence of a significant amount of molecular gas, which is almost equal to the stellar mass, and a number of prominent stellar clusters, which suggest recently triggered star formation. Conclusions. These data show that MeerKAT produces exquisite imaging data. The forthcoming full-depth survey observations of ESO 302-G014 and other sample galaxies will, therefore, offer insights into the fate of neutral gas as it moves from the intergalactic medium onto galaxies.

scholarly journals The distribution of atomic hydrogen in the galaxy

1958 ◽  
Vol 5 ◽  
pp. 16-22
Author(s):  
H. C. Van De Hulst
Keyword(s):  
The Netherlands ◽  
Radio Astronomy ◽  
Atomic Hydrogen ◽  
Neutral Hydrogen ◽  
The Past ◽  
The Galaxy ◽  
Inner Parts

It is my privilege to report here about the investigations of the distribution of neutral hydrogen in the Galaxy. These observations, conducted by the Netherlands Foundation for Radio Astronomy, were made at Kootwijk and reduced at the Leiden Observatory. More than a dozen persons have participated in this work during the past year. Among them are Prof. Oort and myself, but I should mention three in particular: C. A. Muller has perfected the instruments even further and has supervised the observations that were made during 24 hr a day. G. Westerhout has supervised most of the reductions at Leiden and has prepared the map and model of the outer parts of the Galaxy. M. Schmidt has unravelled the situation in the inner parts of the Galaxy, on the basis of his observations made for this purpose.

The Spin Temperature of the Interstellar Neutral Hydrogen

1969 ◽  
Vol 1 (5) ◽  
pp. 215-216 ◽  
Author(s):  
V. Radhakrishnan ◽  
J. D. Murray
Keyword(s):  
Galactic Plane ◽  
Neutral Hydrogen ◽  
Spin Temperature ◽  
The Past ◽  
Brightness Temperatures ◽  
Direct Measurements ◽  
Absorption Studies ◽  
The Galaxy ◽  
Considerable Controversy ◽  
Emission Studies

The lack of any direct measurements on the spin temperature of the neutral hydrogen in the Galaxy has led to considerable controversy in the past. Estimates of the temperature have depended strongly on whether they are based on emission or absorption studies. The widely accepted value of 125°K based on emission studies dates back to Schmidt. He adopted this figure on the premise that the maximum observed brightness temperatures in the galactic plane were in directions of high optical depth. The brightness temperature was then equated with the spin temperature on the assumption that the temperature did not fluctuate very much in a large region around the Sun.

Interstellar gas in the central region of the Galaxy

1967 ◽  
Vol 31 ◽  
pp. 239-251 ◽  
Author(s):  
F. J. Kerr
Keyword(s):  
Central Region ◽  
Galactic Plane ◽  
Neutral Hydrogen ◽  
Continuum Emission ◽  
Galactic Centre ◽  
Interstellar Gas ◽  
Hydrogen Recombination ◽  
The Galaxy ◽  
Centre Region ◽  
The Relationship

A review is given of information on the galactic-centre region obtained from recent observations of the 21-cm line from neutral hydrogen, the 18-cm group of OH lines, a hydrogen recombination line at 6 cm wavelength, and the continuum emission from ionized hydrogen.Both inward and outward motions are important in this region, in addition to rotation. Several types of observation indicate the presence of material in features inclined to the galactic plane. The relationship between the H and OH concentrations is not yet clear, but a rough picture of the central region can be proposed.

The Long View of Planetary Systems

2018 ◽  
Author(s):  
Karel Schrijver
Keyword(s):  
Solar System ◽  
Milky Way ◽  
Planetary Systems ◽  
Giant Planets ◽  
Milky Way Galaxy ◽  
Population Statistics ◽  
The Past ◽  
General Terms ◽  
The Galaxy ◽  
The Universe

How many planetary systems formed before our’s did, and how many will form after? How old is the average exoplanet in the Galaxy? When did the earliest planets start forming? How different are the ages of terrestrial and giant planets? And, ultimately, what will the fate be of our Solar System, of the Milky Way Galaxy, and of the Universe around us? We cannot know the fate of individual exoplanets with great certainty, but based on population statistics this chapter sketches the past, present, and future of exoworlds and of our Earth in general terms.

scholarly journals Spiral morphology in an intensely star-forming disk galaxy more than 12 billion years ago

Science ◽  
2021 ◽  
pp. eabe9680
Author(s):  
Takafumi Tsukui ◽  
Satoru Iguchi
Keyword(s):  
Big Bang ◽  
Compact Structure ◽  
Spiral Arms ◽  
Star Forming ◽  
Gas Kinematics ◽  
Internal Structures ◽  
The Galaxy ◽  
Galaxy Center ◽  
The Big Bang ◽  
Tidal Tails

Spiral galaxies have distinct internal structures including a stellar bulge, disk and spiral arms. It is unknown when in cosmic history these structures formed. We analyze observations of BRI 1335–0417, an intensely star-forming galaxy in the distant Universe, at redshift 4.41. The [C ii] gas kinematics show a steep velocity rise near the galaxy center and have a two-armed spiral morphology, which extends from about 2 to 5 kiloparsecs in radius. We interpret these features as due to a central compact structure, such as a bulge; a rotating gas disk; and either spiral arms or tidal tails. These features had formed within 1.4 billion years after the Big Bang, long before the peak of cosmic star formation.

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