scholarly journals 3D structure of the H ii region Sh2-235 from tunable-filter optical observations

2020 ◽  
Vol 497 (1) ◽  
pp. 1050-1058 ◽  
Author(s):  
M S Kirsanova ◽  
P A Boley ◽  
A V Moiseev ◽  
D S Wiebe ◽  
R I Uklein
Keyword(s):  
Column Density ◽  
3D Structure ◽  
Far Infrared ◽  
Tunable Filter ◽  
Optical Observations ◽  
Special Astrophysical Observatory ◽  
Neutral Medium ◽  
Neutral Material ◽  
H Ii Region ◽  
Academy Of Sciences

ABSTRACT We present observations of the H α, H β, [S ii] λλ6716, 6731 and [N ii] λ6583 emission lines in the galactic H ii region Sh2-235 with the Mapper of Narrow Galaxy Lines (MaNGaL), a tunable filter at the 1-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences. We show that the H ii region is obscured by neutral material with AV ≈ 2−4 mag. The area with the highest AV is situated to the south-west from the ionizing star and coincides with a maximum detected electron density of ≳300 cm−3. The combination of these results with archive AKARI far-infrared data allows us to estimate the contribution of the front and rear walls to the total column density of neutral material in S235 and explain the 3D structure of the region. The H ii region consist of a denser, more compact portion deeply embedded in the neutral medium and the less dense and obscured gas. The front and rear walls of the H ii region are inhomogeneous, with the material in the rear wall having a higher column density. We find a two-sided photodissociation region in the dense clump S235 East 1, illuminated by a UV field with G0 = 50−70 and 200 Habing units in the western and eastern parts, respectively.

scholarly journals THz Observations of the Cool Neutral Medium

2012 ◽  
Vol 8 (S288) ◽  
pp. 135-138
Author(s):  
John M. Dickey
Keyword(s):  
Column Density ◽  
Far Infrared ◽  
Neutral Medium ◽  
Spectral Structure ◽  
Kinetic Temperature ◽  
Far Infrared Spectroscopy ◽  
Dome A ◽  
Physical Conditions ◽  
Low Latitudes ◽  
Atomic Phase

AbstractThe astrophysical drivers for far-infrared spectroscopy of the Galactic interstellar medium using a 15m class telescope on Dome A are compelling. For the diffuse, atomic phase, the most important lines in the far-IR spectrum are OIat 63μm and CIIat 158μm. These are the dominant cooling lines of the cool, neutral medium, and they show rich spectral structure in Herschel observations at low latitudes. But theory predicts that they should both be highly sub-thermal in excitation, so that the level populations are not in equilibrium with the kinetic temperature of the gas. A large single dish telescope or an interferometer may be able to study the absorption and emission to determine the optical depth and column density of atoms and the physical conditions in the emission regions. Comparison of Herschel CIIspectra with 21-cm absorption spectra indicates that a significant fraction of the 158μm flux may be coming from the atomic rather than the molecular phase.

scholarly journals N/O Abundances in Planetary Nebulae from Far-Infrared Line Observations

1989 ◽  
Vol 131 ◽  
pp. 214-214
Author(s):  
Harriet L. Dinerstein ◽  
Michael W. Werner
Keyword(s):  
Planetary Nebulae ◽  
Far Infrared ◽  
Optical Observations ◽  
Type I ◽  
Local Electron ◽  
Extreme Type ◽  
Order Of Magnitude ◽  
Progenitor Stars ◽  
Infrared Array ◽  
Atomic Parameters

Measurements of the [O III] 52, 88 μm and [N III] 57 μm fine-structure emission lines have been obtained for nine planetary nebulae, using the facility far-infrared array spectrometer on NASA's Kuiper Airborne Observatory. The N++/O++ ratios determined from these observations range by more than an order of magnitude among the sample. Using recent improved values for the atomic parameters, we find that the N++/O++ ratios agree fairly well with values of N+/O+ determined from optical lines in the same objects. The highest N++/O++ values, found for the extreme “Type I” nebulae NGC 2440 and NGC 6302, are approximately unity. These results imply that the synthesis and mixing of nitrogen must be extremely efficient in the progenitor stars of some planetary nebulae, and that these nebulae are significant sources of nitrogen to the interstellar medium. The local electron densities derived from the intensity ratios of the two [O III] lines are generally lower than values in the literature determined from small-beam optical observations of other ions, such as [O II]. This effect can be understood in terms of the presence of clumpy structure in the nebula, since the far-infrared lines have fairly low critical densities for collisional de-excitation and therefore are preferentially emitted from low-density gas.

scholarly journals An extensive study of interstellar matter in the IC 1396 region using several molecular lines and transitions of CO and far-infrared maps from IRAS

1991 ◽  
Vol 147 ◽  
pp. 513-514
Author(s):  
H. Weikard ◽  
K. Sugitani ◽  
G. Duvert ◽  
M. Miller
Keyword(s):  
Molecular Clouds ◽  
Far Infrared ◽  
Extensive Study ◽  
Interstellar Matter ◽  
Molecular Lines ◽  
H Ii Region

IC 1396 is an H II region in Cepheus excited by the massive 06.5 star HD 206267. The distance is about 750 pc. The region exhibits a number of bright-rimmed molecular clouds in which outflows have been detected (Sugitani et al. 1989, Duvert et al. 1990).

Far-infrared observations of M17 - The interaction of an H II region with a molecular cloud

1979 ◽  
Vol 233 ◽  
pp. 575 ◽  
Author(s):  
I. Gatley ◽  
E. E. Becklin ◽  
K. Sellgren ◽  
M. W. Werner
Keyword(s):  
Molecular Cloud ◽  
Far Infrared ◽  
Infrared Observations ◽  
H Ii Region

Far-infrared mapping of the double-lobed H II region S106

1982 ◽  
Vol 258 ◽  
pp. 568 ◽  
Author(s):  
P. M. Harvey ◽  
I. Gatley ◽  
H. A., Jr. Thronson ◽  
M. W. Werner
Keyword(s):  
Far Infrared ◽  
H Ii Region

scholarly journals Binary and multiple magnetic Ap/Bp stars

2013 ◽  
Vol 9 (S302) ◽  
pp. 317-319
Author(s):  
Denis Rastegaev ◽  
Yuri Balega ◽  
Vladimir Dyachenko ◽  
Alexander Maksimov ◽  
Evgenij Malogolovets
Keyword(s):  
Magnetic Fields ◽  
Proper Motion ◽  
Special Astrophysical Observatory ◽  
Full Version ◽  
Short Period ◽  
Magnetic Stars ◽  
Total Fraction ◽  
Academy Of Sciences ◽  
First Time ◽  
Prominent Peak

AbstractWe present the results of speckle interferometric observations of 273 magnetic stars most of which are Ap/Bp type. All observations were made at the 6-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences. We resolved 58 binary and 5 triple stars into individual components. Almost half of these stars were astrometrically resolved for the first time. The fraction of speckle interferometric binaries/multiples in the sample of stars with confirmed magnetic fields is 23%. We expect that the total fraction of binaries/multiples in the sample with account for spectroscopic short-period systems and wide common proper motion pairs can be twice higher. The detected speckle components have a prominent peak in the ρ distribution that corresponds to the closest resolved pairs. Full version of present paper is available in electronic form at http://arxiv.org/abs/1308.3168.

scholarly journals Two epoch spectro-imagery of FS Tau B outflow system

2019 ◽  
Vol 627 ◽  
pp. A94
Author(s):  
T. A. Movsessian ◽  
T. Yu. Magakian ◽  
A. N. Burenkov
Keyword(s):  
Physical Nature ◽  
Mach Disk ◽  
Special Astrophysical Observatory ◽  
Unusual Behavior ◽  
Fabry Perot ◽  
Bow Shocks ◽  
Points Of View ◽  
Academy Of Sciences ◽  
Reflection Nebulae ◽  
Outflow System

Context. Herbig–Haro (HH) flows exhibit a large variety of morphological and kinematical structures such as bow shocks, Mach disks, and deflection shocks. Both proper motion (PM) and radial velocity investigations are essential to understand the physical nature of such structures. Aims. We investigate the kinematics and PM of spectrally separated structures in the FS Tau B HH flow. Collating these data makes it possible to understand the origin of these structures and to explain the unusual behavior of the jet. Besides, the study of emission profiles in the associated reflection nebulae allows us to consider the source of the outflow both from edge-on and pole-on points of view. Methods. We present the data obtained with the 6 m telescope at the Special Astrophysical Observatory of the Russian Academy of Sciences using the SCORPIO multimode focal reducer with a scanning Fabry–Perot interferometer. Two epochs of the observations of the FS Tau B region in Hα emission (2001 and 2012) allowed us to measure the PM of the spectrally separated inner structures of the jet. Results. In addition to already known emission structures in the FS Tau B system, we discover new features in the extended part of the jet and in the counter-jet. Moreover, we reveal a new HH knot in the HH 276 independent outflow system and point out its presumable source. In the terminal working surface of the jet, structures with different radial velocities have PMs of the same value. This result can be interpreted as the direct observation of bow-shock and Mach disk regions. A bar-like structure, located southwest from the source demonstrates zero PM and can be considered as one more example of deflection shock. An analysis of Hα profiles in the reflection nebulae R1 and R3 indicates the uniqueness of this object, which can be studied in pole-on and edge-on directions simultaneously.

scholarly journals Radial distributions of constituents in M33, the Galaxy, and M51

1985 ◽  
Vol 106 ◽  
pp. 431-434
Author(s):  
Elly M. Berkhuijsen ◽  
Ulrich Klein
Keyword(s):  
Radio Emission ◽  
Blue Light ◽  
Column Density ◽  
Surface Brightness ◽  
Far Infrared ◽  
Abundance Ratio ◽  
Nonthermal Radio ◽  
The Galaxy ◽  
Nonthermal Radio Emission

The radial distributions of the surface brightness or column density of thermal and nonthermal radio emission, far-infrared (FIR) emission, blue light, HI and CO in the Sc galaxies M33 and M51 are compared with the corresponding distributions in the Galaxy. Information on the variation of the absorption at Hα and on the variation of the abundance ratio O/H is also shown.

scholarly journals Cloud formation in the atomic and molecular phase: H I self absorption (HISA) towards a giant molecular filament

2020 ◽  
Vol 634 ◽  
pp. A139 ◽  
Author(s):  
Y. Wang ◽  
S. Bihr ◽  
H. Beuther ◽  
M. R. Rugel ◽  
J. D. Soler ◽  
...  
Keyword(s):  
Interstellar Medium ◽  
Power Law ◽  
Molecular Clouds ◽  
Column Density ◽  
Cloud Formation ◽  
Neutral Medium ◽  
Molecular Component ◽  
Density Peaks ◽  
Log Normal ◽  
High Column

Molecular clouds form from the atomic phase of the interstellar medium. However, characterizing the transition between the atomic and the molecular interstellar medium (ISM) is a complex observational task. Here we address cloud formation processes by combining H I self absorption (HISA) with molecular line data. Column density probability density functions (N-PDFs) are a common tool for examining molecular clouds. One scenario proposed by numerical simulations is that the N-PDF evolves from a log-normal shape at early times to a power-law-like shape at later times. To date, investigations of N-PDFs have been mostly limited to the molecular component of the cloud. In this paper, we study the cold atomic component of the giant molecular filament GMF38.1-32.4a (GMF38a, distance = 3.4 kpc, length ~ 230 pc), calculate its N-PDFs, and study its kinematics. We identify an extended HISA feature, which is partly correlated with the 13CO emission. The peak velocities of the HISA and 13CO observations agree well on the eastern side of the filament, whereas a velocity offset of approximately 4 km s−1 is found on the western side. The sonic Mach number we derive from the linewidth measurements shows that a large fraction of the HISA, which is ascribed to the cold neutral medium (CNM), is at subsonic and transonic velocities. The column density of the CNM part is on the order of 1020 to 1021 cm−2. The column density of molecular hydrogen, traced by 13CO, is an order of magnitude higher. The N-PDFs from HISA (CNM), H I emission (the warm and cold neutral medium), and 13CO (molecular component) are well described by log-normal functions, which is in agreement with turbulent motions being the main driver of cloud dynamics. The N-PDF of the molecular component also shows a power law in the high column-density region, indicating self-gravity. We suggest that we are witnessing two different evolutionary stages within the filament. The eastern subregion seems to be forming a molecular cloud out of the atomic gas, whereas the western subregion already shows high column density peaks, active star formation, and evidence of related feedback processes.

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