scholarly journals The Shaping of the Optical Jet of the Galaxy NGC 4258

1989 ◽  
Vol 120 ◽  
pp. 359-363
Author(s):  
P. Martin ◽  
J.-R. Roy ◽  
L. Noreau ◽  
K.-Y. Lo
Keyword(s):  
High Resolution ◽  
Interstellar Medium ◽  
Spiral Galaxy ◽  
Small Angle ◽  
Aperture Synthesis ◽  
The Galaxy ◽  
Barred Spiral Galaxy ◽  
Co Observations

SUMMARY.Hα + [NII] and red continuum CCD images as well as high resolution aperture synthesis CO maps were obtained in order to study the optical jet of the barred spiral galaxy NGC 4258. The CO observations show two clouds near the center of the galaxy; these clouds outline a channel and the Hα jet follows this channel. The observations are consistent with the jet being in or making a small angle with the galaxy plane. It is concluded that the interstellar medium may play an important role in making jets detectable optically and in shaping their forms.

scholarly journals 5.18. Molecular gas in the poststarburst galaxy NGC7331

1998 ◽  
Vol 184 ◽  
pp. 247-248
Author(s):  
T. Tosaki ◽  
Y. Shioya
Keyword(s):  
High Resolution ◽  
Spiral Galaxy ◽  
Stellar Populations ◽  
Optical Spectra ◽  
Molecular Gas ◽  
Early Type ◽  
Origin And Evolution ◽  
Co Observations

To understand the origin and evolution of starburst activity, we must study the full evolution of starburst; i.e., pre-, on-going, and post-starburst phases. It seems reasonable to suppose the numerous A-type stars indicate past starburst and they show strong Balmer absorption. NGC7331, nearby early-type spiral galaxy, is one of the poststarburst galaxies which show strong Balmer absorption. The optical spectra of NGC7331 were dominated by component of intermediate-age (5 × 109 years) stellar populations (Ohyama & Taniguchi 1996). We present the result of the high resolution CO observations of NGC7331 using Nobeyama Milimeter Array.

scholarly journals Zoom-in cosmological hydrodynamical simulation of a star-forming barred, spiral galaxy at redshift z = 2

2019 ◽  
Vol 488 (4) ◽  
pp. 4674-4689 ◽  
Author(s):  
Fiorenzo Vincenzo ◽  
Chiaki Kobayashi ◽  
Tiantian Yuan
Keyword(s):  
Star Formation ◽  
Angular Velocity ◽  
Spiral Galaxy ◽  
Stellar Populations ◽  
Spiral Arms ◽  
Star Forming ◽  
Thin Disc ◽  
The Galaxy ◽  
Barred Spiral Galaxy ◽  
Zoom In

ABSTRACTWe present gas and stellar kinematics of a high-resolution zoom-in cosmological chemodynamical simulation, which fortuitously captures the formation and evolution of a star-forming barred spiral galaxy, from redshift z ∼ 3 to z ∼ 2 at the peak of the cosmic star formation rate. The galaxy disc grows by accreting gas and substructures from the environment. The spiral pattern becomes fully organized when the gas settles from a thick (with vertical dispersion σv > 50 km s−1) to a thin (σv ∼ 25 km s−1) disc component in less than 1 Gyr. Our simulated disc galaxy also has a central X-shaped bar, the seed of which formed by the assembly of dense gas-rich clumps by z ∼ 3. The star formation activity in the galaxy mainly happens in the bulge and in several clumps along the spiral arms at all redshifts, with the clumps increasing in number and size as the simulation approaches z = 2. We find that stellar populations with decreasing age are concentrated towards lower galactic latitudes, being more supported by rotation, and having also lower velocity dispersion; furthermore, the stellar populations on the thin disc are the youngest and have the highest average metallicities. The pattern of the spiral arms rotates like a solid body with a constant angular velocity as a function of radius, which is much lower than the angular velocity of the stars and gas on the thin disc; moreover, the angular velocity of the spiral arms steadily increases as a function of time, always keeping its radial profile constant. The origin of our spiral arms is also discussed.

scholarly journals ROSAT Observations of NGC 4258

1997 ◽  
Vol 166 ◽  
pp. 547-550
Author(s):  
Andreas Vogler ◽  
Wolfgang Pietsch
Keyword(s):  
Interstellar Medium ◽  
Point Source ◽  
Brightness Temperature ◽  
Spiral Galaxy ◽  
Surface Brightness ◽  
Point Sources ◽  
X Rays ◽  
X Ray ◽  
The Galaxy

AbstractWe performed deep follow up observations of the active spiral galaxy NGC 4258 with the ROSAT HRI and PSPC to study the different emission components. The overall luminosity of NGC 4258 is Lx ~ 2 × 1040 erg s−1 in the 0.1 – 2.4 keV ROSAT band. Besides a weak nuclear point source (Lx ≲ 1038 erg s−1) fourteen point sources are detected in the NGC 4258 disk (integral Lx ~ 3 × 1039 erg s− 1). The bulk of the X-ray emission is not resolved. The main contributions are explained by hot interstellar medium along the anomalous spiral arms of NGC 4258 (Lx ~ 1 × 1040, T ~ 0.4 keV) and by interstellar medium escaping from NGC 4258 disk into the approaching halo hemisphere (Lx ~ 4 × 1039 erg s−1, T ~ 0.2 keV)Surface brightness, temperature and absorption profiles have been taken for the X-rays in the regions of the anomalous arms. The highest and lowest absorption was received for the NW and SE tips of the arms, respectively. Our X-ray findings are compared to a model of the anomalous arms which suggests that the bar of the galaxy causes shocks in the interstellar medium and might heat a small part of it to X-ray temperatures.

scholarly journals The Contribution of Hipparcos to the Study of the Stellar Metal-Rich Population in the Solar Neighbourhood

1998 ◽  
Vol 11 (1) ◽  
pp. 566-566
Author(s):  
G. Cayrel de Strobel ◽  
C. Soubiran ◽  
Y. Lebreton
Keyword(s):  
High Resolution ◽  
Interstellar Medium ◽  
Evolved Stars ◽  
Spectroscopic Analyses ◽  
The Galaxy ◽  
Solar Metallicity ◽  
Metal Abundances ◽  
The Mean ◽  
Effective Temperatures ◽  
Absolute Magnitudes

The ‘1996 Edition’ of the Catalogue of [Fe/H] determinations by Cayrel de Strobel et al. (1997, A&A S 124,1) and two recent papers by Castro et al. (1997, AJ Vol.114, N.1) and by Feltzing and Gustafsson (A&A in press) have made possible to increase in the theoretical HR diagram (log Teff, Mbol the number of SMR stars. The SMR Stars of this new enlarged sample had to have reliable absolute magnitudes, coming all from Hipparcos parallaxes, precise bolometric corrections, effective temperatures and metal abundances from high resolution detailed spectroscopic analyses. With the help of an appropriate grid of isochrones computed by Lebreton (1997, Perryman et al. A&A, in press), ‘turn-off ages’could then be attributed to the slightly evolved stars (subgiants) of the sample. The (log Teff, Mbol) diagram constituted by the new sample of SMR stars, shows that the conclusions in a former paper by Cayrel de Strobel (1987, A&AJ 8,141) remain valid: the SMR stars areold stars in spite of their higher than solar metallicity. The result, that metal-rich stars were in the mean old stars, was interpreted in the 1987 paper as due to a more chemical uniformity of the nowadays interstellar medium of the Galaxy with respect of the older much more active interstellar medium.

scholarly journals The Circumnuclear Region in NGC 4321

1995 ◽  
Vol 10 ◽  
pp. 539-542
Author(s):  
J.H. Knapen ◽  
J.E. Beckman ◽  
I. Shlosman ◽  
C.H. Heller ◽  
R.F. Peletier ◽  
...  
Keyword(s):  
High Resolution ◽  
Spiral Galaxy ◽  
Resonance Interaction ◽  
Dynamical Model ◽  
High Resolution Imaging ◽  
Spiral Arms ◽  
Near Ir ◽  
Resolution Imaging ◽  
Barred Spiral Galaxy

AbstractWe present results from a recent study of the inner 1 kpc zone of the weakly barred spiral galaxy NGC 4321 (M100), which reveals a circumnuclear starburst, organized in a pair of tightly-wound spiral arms. Combining high-resolution imaging in the optical and near-IR with a detailed dynamical model, we show that the morphology of this region can be explained by a resonance interaction between the disk and the stellar bar and its effects on the gas.

scholarly journals CO Observations of M51

1983 ◽  
Vol 100 ◽  
pp. 53-54 ◽  
Author(s):  
G. Rydbeck ◽  
G. Pilbratt ◽  
Å. Hjalmarson ◽  
H. Olofsson ◽  
O. E. H. Rydbeck
Keyword(s):  
Spiral Galaxy ◽  
Signal To Noise Ratio ◽  
Beam Size ◽  
Signal To Noise ◽  
Antenna Beam ◽  
The Galaxy ◽  
Integrated Intensity ◽  
Noise Ratio ◽  
Co Observations ◽  
Intensity Contrast

We present observations, which are part of an ongoing investigation, of the CO (J=1–0) emission in the spiral galaxy M51. The spectra were obtained in a beamswitched on-on mode with the Onsala 20 m antenna (beam size ~33″), equipped with a cooled mixer and a 512 ×1 MHz multichannel receiver, and are shown in Figure 1. The inset diagram shows the observed positions superposed on the optical outline of the galaxy. With the present signal-to-noise ratio there is no evidence for an arm-interarm intensity contrast. This is even more apparent in integrated intensity. This result agrees with the lower resolution findings of Rickard et al. (1981). We have observed 13CO in one position (22″ south of the center). The 13CO to 12CO ratio, ∼0.1, agrees with Bell results from observations with a 1:7 beam (Encrenaz et al. 1979).

scholarly journals A High-Resolution CO Mapping of the Nucleus of the Barred-Spiral Galaxy, M83

1994 ◽  
Vol 140 ◽  
pp. 341-342 ◽  
Author(s):  
Toshihiro Handa ◽  
Sumio Ishizuki ◽  
Ryohei Kawabe
Keyword(s):  
High Resolution ◽  
Spiral Galaxy ◽  
Central Region ◽  
Molecular Gas ◽  
Nuclear Region ◽  
Circular Rotation ◽  
Frequency Coverage ◽  
Barred Spiral Galaxy ◽  
Gas Response ◽  
Co Emission

M83 is the best sample to investigate gas response to bar potential because it is one of the nearest galaxy with a pronounced bar structure (distance=3.7 Mpc). Handa et al. (1990) observed it with the Nobeyama 45-m telescope in CO(J=1-0) and found concentration of the CO emission to the dust lanes along the bar and non-circular rotation. However we need better spatial resolution in order to investigate kinematics and distribution of molecular gas in the nuclear region. So we observe the central region of M83 using the Nobeyama Millimeter Array. The synthesized beamsize was 12″ × 6″ and frequency coverage was 325 km s-1.

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