The Nature of Boxy/Peanut Spiral Galaxies: Overview and New Results

1997 ◽  
Vol 14 (2) ◽  
pp. 146-158 ◽  
Author(s):  
M. Bureau ◽  
K. C. Freeman
Keyword(s):  
Formation Mechanism ◽  
Vertical Structure ◽  
Near Infrared ◽  
Infrared Imaging ◽  
Spiral Galaxies ◽  
Physical Conditions ◽  
Bar Buckling ◽  
Line Imaging ◽  
Observational Program

AbstractThe formation mechanism of boxy/peanut-shaped bulges in spiral galaxies has been a problem for many years. We briefly review here the possible formation scenarios for boxy/peanut bulges, concentrating on both the bar-buckling and accretion hypotheses, and then describe an observational program aimed at testing those various theories and studying the vertical structure of edge-on bars. Our program includes optical long-slit spectroscopy, Hiline-imaging, near-infrared imaging, and multi-band optical imaging. New spectroscopic results (both optical and Hi) are presented on seven galaxies, including five boxy/peanut-bulge spirals. Based on Kuijken & Merrifield's (1995) idea for detecting edge-on bars, we argue that these observations constitute a strong case in favour of the bar-buckling mechanism for the formation of boxy/peanut-shaped bulges, but they also raise many questions and prompt for more detailed modelling to be made. The implications of the observations concerning the determination of rotation curves and of the physical conditions in bulges are also discussed.

scholarly journals Circumnuclear regions in barred spiral galaxies — I. Near-infrared imaging

2000 ◽  
Vol 317 (2) ◽  
pp. 234-248 ◽  
Author(s):  
D. Pérez-Ramírez ◽  
J. H. Knapen ◽  
R. F. Peletier ◽  
S. Laine ◽  
R. Doyon ◽  
...  
Keyword(s):  
Near Infrared ◽  
Infrared Imaging ◽  
Spiral Galaxies ◽  
Near Infrared Imaging ◽  
Barred Spiral Galaxies

scholarly journals Tracing Molecular Emission in Spiral Galaxies: The Near Infrared Correspondence

1994 ◽  
Vol 140 ◽  
pp. 370-371
Author(s):  
R. L. Hurt ◽  
J. L. Turner ◽  
D. Levine ◽  
K. M. Merrill ◽  
I. Gatley
Keyword(s):  
Large Scale ◽  
Near Infrared ◽  
Infrared Imaging ◽  
Spiral Galaxies ◽  
Molecular Structures ◽  
Optical Observations ◽  
Near Infrared Imaging ◽  
Imaging Arrays ◽  
Molecular Emission ◽  
Infrared Extinction

Near infrared imaging can be a powerful tool in tracing the densest molecular structures in galaxies. The observable molecular emission originates in large molecular cloud complexes which are also subject to significant extinctions caused by the associated dust. It can be difficult to distinguish between regions of moderate and large molecular density with optical observations as both will appear optically thick. Since extinction in the near infrared is only about a tenth of the corresponding visual extinction, multi-band near infrared imaging will trace the regions of the highest optical depths much more effectively. With the advent of large format infrared imaging arrays it is now possible to use infrared extinction maps as a probe of the large scale distribution of molecular emission in extragalactic sources.

scholarly journals Multi-Color Surface Photometry of Nearby Galaxies

1998 ◽  
Vol 179 ◽  
pp. 285-286
Author(s):  
T. Ichikawa ◽  
N. Itoh ◽  
K. Yanagisawa
Keyword(s):  
Star Formation ◽  
Galaxy Evolution ◽  
Near Infrared ◽  
Infrared Imaging ◽  
Spiral Galaxies ◽  
Stellar Structure ◽  
Star Formation History ◽  
Optical Observations ◽  
Wide Field ◽  
Formation History

Near-infrared (NIR) emission in galaxies is mainly radiated by old population low temperature stars, which construct the basic stellar structure and keep the trails of past galaxy evolution. On the other hand, optical observations show recent star formation activity, especially in spiral galaxies. Therefore multi-color observations from optical to near-infrared wavelengths are very important to understand the past and recent star-formation history. Nearby large galaxies are well studied not only in optical but also in mid- and far-infrared by IRAS, CO and HI radio observations. However, the study in the near-infrared is still limited because large format arrays are not common. Here we show a wide-field, near-infrared imaging of nearby elliptical and spiral galaxies and discuss their star-formation history.

scholarly journals Development of a Near-Infrared Imaging System for Determination of Rice Moisture

2006 ◽  
Vol 83 (5) ◽  
pp. 498-504 ◽  
Author(s):  
Lian-Hsiung Lin ◽  
Fu-Ming Lu ◽  
Yung-Chiung Chang
Keyword(s):  
Near Infrared ◽  
Infrared Imaging ◽  
Imaging System ◽  
Near Infrared Imaging ◽  
Infrared Imaging System

scholarly journals Stellar content of obscured compact H II regions

2003 ◽  
Vol 212 ◽  
pp. 467-473 ◽  
Author(s):  
Margaret M. Hanson ◽  
Lex Kaper ◽  
Arjan Bik ◽  
Fernando Comerón ◽  
Joachim Puls ◽  
...  
Keyword(s):  
Massive Star ◽  
Near Infrared ◽  
Massive Stars ◽  
Model Atmosphere ◽  
Spectroscopic Studies ◽  
H Ii Regions ◽  
Stellar Content ◽  
High Quality ◽  
Physical Conditions

Near-infrared, spectroscopic studies of central ionizing sources of very young H ii regions is presented in conjunction with a recently available, sophisticated atmospheric code to constrain the physical conditions and environment of very massive stars at very early stages of evolution. Combining high quality near-infrared spectroscopy of very young massive stars with model atmosphere calculations should allow for the most accurate quantitative determination of Teff, rotation, L, and log g, and to search for binaries and possible disk or in-fall signatures in forming or recently formed massive stars. These characteristics make up a vital boundary condition constraining theories on massive star formation.

scholarly journals Stellar Populations of a Sample of Tidal Dwarf Galaxies

2004 ◽  
Vol 217 ◽  
pp. 540-545 ◽  
Author(s):  
Peter M. Weilbacher ◽  
Uta Fritze-V. Alvensleben ◽  
Pierre-Alain Duc
Keyword(s):  
Formation Mechanism ◽  
Near Infrared ◽  
Infrared Imaging ◽  
Velocity Structure ◽  
Dwarf Galaxies ◽  
Stellar Populations ◽  
Evolutionary Synthesis ◽  
Optical Images ◽  
Stellar Masses ◽  
Parent Galaxy

We investigate the stellar populations of a sample of Tidal Dwarf Galaxies, combining observations and evolutionary synthesis models to try and reveal their formation mechanism. on optical images we select a first sample of TDGs for which optical spectroscopy is used to measure metallicities and velocity structure. Finally, we estimate ages, burst strengths, and stellar masses from near-infrared imaging in comparison with a dedicated grid of evolutionary synthesis models, to assess if Tidal Dwarfs are formed out of collapsing gas clouds or by an accumulation of old stars from the parent galaxy or by a combination of both.

scholarly journals The Galactic radial abundance gradients of C, N, O, Ne, S, Cl, and Ar from deep spectra of H ii regions

2020 ◽  
Vol 496 (2) ◽  
pp. 1051-1076 ◽  
Author(s):  
K Z Arellano-Córdova ◽  
C Esteban ◽  
J García-Rojas ◽  
J E Méndez-Delgado
Keyword(s):  
Gas Phase ◽  
Milky Way ◽  
Spiral Galaxies ◽  
Direct Determination ◽  
Atomic Data ◽  
H Ii Regions ◽  
Galactic Disc ◽  
Ionized Gas ◽  
Physical Conditions

ABSTRACT We present a reassessment of the radial abundance gradients of C, N, O, Ne, S, Cl, and Ar in the Milky Way using deep spectra of 33 H ii regions gathered from the literature, covering Galactocentric distances from 6 to 17 kpc. The distances of the objects have been revised using Gaia parallaxes. We recalculate the physical conditions and ionic abundances in an homogeneous way using updated atomic data. All the objects have direct determination of the electron temperature, permitting to derive their precise ionic abundances. We analyse and compare different ICF schemes for each element in order to obtain the most confident total abundances. Due to the revised distances, our results do not support previous claims about a possible flattening of the O/H gradient in the inner Galactic disc. We find that the Galactic N/O gradient is rather flat, in contrast to what has been found in other spiral galaxies. The slope of the gradients of some elements is sensitive to the ICF scheme used, especially in the case of Ne. The dispersion around the fit for the gradients of C, N, O, S, Cl, and Ar is of the order of the typical uncertainties in the determination of the abundances, implying the absence of significant inhomogeneities in the chemical composition of the ionized gas phase of the ISM. We find flat gradients of log(S/O) and log(Cl/O) and very shallow or flat ones for log(Ne/O) and log(Ar/O), consistent with a lockstep evolution of Ne, S, Cl, and Ar with respect to O.

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