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1.
Janina Krempeć 《Astrophysics and Space Science》1970,6(1):131-140
The coefficients of correlation between spectroscopic data published by Yamashita (1967) and others for carbon stars and the statistical population indices calculated for these stars at the Toru Observatory are calculated (Table II). The intensity estimates of Cai 4227 Å, Nai D lines, the C13/C12 ratio, then=n(Li/Ca) index, as well as CN and probably C2 bands are higher in population I carbon stars. The CH(G) band and probably hydrogen (H, H, H) lines as well as Baii 4554 and 4934 Å lines are stronger in population II carbon stars. The photoelectric colour indices, corrected for interstellar reddening do not show significant population effects. They can be used as spectral type equivalents. For a population criterion the CH/CN intensity ratio is proposed. 相似文献
2.
E. A. Mallia 《Solar physics》1968,5(3):281-302
An attempt is made to detect the lines of Mg25H and Mg26H in the photospheric spectrum, using calculated isotope shifts. From comparisons with the Mg24H lines of the 2
–2
transition in the (0, 0) band the ratios Mg25/Mg24 = 0.12 ± 0.04 and Mg26/Mg24 = 0.12 ± 0.02 are derived. These are essentially the same as the terrestrial ratios. The profile of one line of Mgi confirms these values.The wavelengths of MgH and C2 lines, when corrected for the gravitational red shift, indicate that macroturbulent (or streaming) velocities die out near log 0 = – 1.0. From the equivalent widths of the MgH lines a rotational temperature of 5132 ± 200 K is obtained and compared to predictions from various model atmospheres. The band oscillator strength is found to be 0.024 ± 0.002, in serious disagreement with the single laboratory determination.The profiles of MgH, C2, CN and some weak atomic lines are used to derive the variation of the radial component of microturbulence with optical depth, on the assumption of streaming velocities of 2.5–3.0 km/sec. A slow increase with increasing height in the photosphere is found, over the range –1.5 < log0< 0.2.The center-limb variation of the equivalent widths of MgH and C2 lines for a wholly inhomogeneous model is found to be the same as for a model which is homogeneous above log 0 = - 1.0. With such a model as the latter, the center-limb variation of the profiles of the selected molecular and atomic lines is moderately-well reproduced by an anisotropic microturbulent velocity with a tangential component of 3 km/sec which seems to be constant with height over the range considered. 相似文献
3.
N.I. Rovenskaya 《Astrophysics and Space Science》2002,281(4):715-727
Intensities of carbon radio recombination lines are analytically described as function of line number, temperature and medium
concentration. Accounting for the process of dielectronic recombination the balance equations for highly excited carbon populations
as b
n-factors are solved by the diffusional approximation. To determine medium temperature and density with the experimental amplification
coefficients the system of boundary condition equations is formulated as
. Analytically found in the range of temperatures T
e = 25-100, 104 K the line amplification coefficients are compared with the numerical solutions. By the method of radio lines intensity ratio
of carbon for the observations at frequencies 34.5–25 MHz the density magnitudes are calculated towards Cassiopeia A as function
of temperature.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
4.
N. G. Kantharia W. M. Goss D. Anish Roshi Niruj R. Mohan Francois Viallefond 《Journal of Astrophysics and Astronomy》2007,28(1):41-53
We report multi-frequency radio continuum and hydrogen radio recombination line observations of HII regions near l = 24.8°, b = 0.1° using the Giant Metrewave Radio Telescope (GMRT) at 1.28 GHz (n = 172), 0.61 GHz (n = 220) and the Very Large Array (VLA) at 1.42 GHz (n = 166). The region consists of a large number of resolved HII regions and a few compact HII regions as seen in our continuum
maps, many of which have associated infrared (IR) point sources. The largest HII region at l = 24.83° and b = 0.1° is a few arcmins in size and has a shell-type morphology. It is a massive HII region enclosing ∼550 M⊙ with a linear size of 7 pc and an rms electron density of ∼110 cm−3 at a kinematic distance of 6 kpc. The required ionization can be provided by a single star of spectral type O5.5.
We also report detection of hydrogen recombination lines from the HII region at l = 24.83° and b = 0.1° at all observed frequencies near V
lsr
= 100 km s−1. We model the observed integrated line flux density as arising in the diffuse HII region and find that the best fitting model
has an electron density comparable to that derived from the continuum. We also report detection of hydrogen recombination
lines from two other HII regions in the field. 相似文献
5.
I. Zinchenko A. Lapinov K. Mattila M. Toriseva 《Astrophysics and Space Science》1995,224(1-2):585-586
We searched for the CSJ = 2 – 1 emission towards 29 southern H2O and H2O/OH masers and 1 OH maser with the SEST radio telescope. We detected and mapped 24 CS emitting regions probably associated with 27 H2O masers. The C34SJ = 2 – 1 and COJ = 1 – 0 lines were also observed at the grid positions closest to the CS peaks. Four cores were mapped in the CSJ = 5 – 4 and C34SJ = 2 – 1 lines. 相似文献
6.
A. A. de Almeida 《Earth, Moon, and Planets》1993,60(1):69-79
Emission fluxes of CN, G2 and C3 carbon-bearing molecular species observed in the spectra of the nuclear fragment A and D of comet West (1976VI) are analysed in the framework of Haser's two-component model with radial outflow symmetry. Gas production rates have been derived and their ratios obtained. We find these vary as Q
r
n
(where 1.0r2.6 is the heliocentric distance in AU) with photometric parametern = -4.11 (CN), -2.68 (C2), -1.89 (C3) andQ
x
/Q
y
r
n
withn = 2.22 (C3/CN), 1.42 (C2/CN), -0.79 (C2/C3). The gas-to-dust ratio, dust production rates in arbitrary units, total number of dust particles in the field of view and an effective radius Reff 2.0 km for the principal nuclear fragmentA is also estimated. 相似文献
7.
High‐resolution mass spectrometry (HRMS) imaging by desorption electrospray ionization (DESI) coupled with Orbitrap MS using methanol (MeOH) spray was performed on a fragment of the Murchison (CM2) meteorite in this study. Homologues of CnH2n–1N2+ (n = 7–9) and CnH2nNO+ (n = 9–14) were detected on the sample surface by the imaging. A high‐performance liquid chromatography (HPLC)/HRMS analysis of MeOH extracts from the sample surface after DESI/HRMS imaging indicated that the CnH2n–1N2+ homologues corresponds to alkylimidazole, and that a few isomers of the CnH2nNO+ homologues present in the sample. The alkylimidazoles and CnH2nNO+ homologues displayed different spatial distributions on the surface of the Murchison fragment, indicating chromatographic separation effects during aqueous alteration. Moreover, the distribution pattern of compounds is also different among homologues. This is probably also resulting from the separation of isomers by similar chromatographic effects, or different synthetic pathways. Alkylimidazoles and the CnH2nNO+ homologues are mainly distributed in the matrix region of the Murchison by mineralogical observations, which is consistent with previous reports. Altered minerals (e.g., Fe‐oxide, Fe‐sulfide, and carbonates) occurred in this region. However, no clear relationship was found between these minerals and the organic compounds detected by DESI/HRMS imaging. Although this result might be due to scale differences between the spatial resolution of DESI/HRMS imaging and the grain size in the matrix of the Murchison, our results would indicate that alkylimidazoles and the CnH2nNO+ homologues in the Murchison fragment were mainly synthesized by different processes from hydrothermal alteration on the parent body. 相似文献
8.
The [SI] lines are due to transitions within the 3s23p4 ground configuration of neutral sulphur. The results are presented from a search for the [Si] lines in the Fraunhofer spectrum. Two identifications are proposed with faint features in the Fraunhofer spectrum: 1D2-1S0 at
= 7725.02 Å and 3P2-1D2 at
= 10821.23 Å. Their measured equivalent widths are shown to confirm the value for the solar abundance of sulphur, logN
S = 7.21 (in the scale logN
H = 12.00), which is derived from the permitted high-excitation lines. These lines give the first convincing identification of [Si] lines in an astrophysical source. 相似文献
9.
Some Bianchi Type IX string cosmological models with bulk viscous fluid for massive string is investigated. To get a determinate
solution, a supplementary condition a=b
n, between metric potentials, is used wherea and b are function of time alone. A particular solution for n=0 is also discussed. The behaviour of the model in presence and absence
of bulk viscosity, is discussed. The physical and implications of the model is also discussed.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
10.
In this paper a method is proposed for computing the equilibrium structures and various other observable physical parameters
of the primary components of stars in binary systems assuming that the primary is more massive than the secondary and is rotating
differentially about its axis. Kippenhahn and Thomas averaging approach (1970) is used in a manner earlier used by Mohan,
Saxena and Agarwal (1990) to incorporate the rotational and tidal effects in the equations of stellar structure. Explicit
expressions for the distortional terms appearing in the stellar structure equations have been obtained by assuming a general
law of differential rotation of the typeω2 = b
0+b
1
s
2+b
2
s
4, where ω is the angular velocity of rotation of a fluid element in the star at a distance s from the axis of rotation, and b
0, b
1, b
2 are suitably chosen numerical constants. The expressions incorporate the effects of differential rotation and tidal distortions
up to second order terms. The use of the proposed method has been illustrated by applying it to obtain the structures and
observable parameters of certain differentially rotating primary components of the binary stars assuming the primary components
to have polytropic structures.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
11.
In this paper we present a method for computing the equilibrium structures and various physical parameters of a primary component
of the binary system assuming that the primary is more massive than the secondary and is rotating differentially according
to the law of the w2 = b0 + b1 × s2 + b2 × s4, w being the angular velocity of rotation of a fluid element distant s from the axis of rotation and b0, b1, b2 suitably chosen numerical constants. This method utilizes the averaging approach of Kippenhahn and Thomas (1997) and the
concept of Roche equipotentials in a manner earlier used by Mohan et al. (1997) to incorporate the effects of rotation and
tidal distortions on the equilibrium structures of certain rotationally and tidally distorted stellar models. The use of the
method has been illustrated by applying it to obtain the structures and some observable parameters of certain differentially
rotating and tidally distorted binary systems whose primary component is assumed to be a white dwarf star. 相似文献
12.
J. M. Fontenla 《Solar physics》1979,64(1):177-186
Intensities and profiles of the H, H, H, K, and D3 lines are measured in a solar prominence. From the profiles of these lines we estimate T = 6400 K and
t = 5.7 km s–1. We construct a simple isothermal model which explains the H intensity and profile for an assumed total particle density n
T = 3 × 1011 cm–3, and a filling factor, = 1/6.From this model we find that the source function in the H line is nearly constant through the prominence. We estimate from the model that the radiative energy loss at the center of the prominence is of the order of 107 erg s–1 g–1. 相似文献
13.
We have detected new HD absorption systems at high redshifts, z
abs = 2.626 and z
abs = 1.777, identified in the spectra of the quasars J0812+3208 and Q1331+170, respectively. Each of these systems consists
of two subsystems. The HD column densities have been determined: log N
HDA = 15.70 ± 0.07 for z
A = 2.626443(2) and log N
HDB = 12.98 ± 0.22 for z
B = 2.626276(2) in the spectrum of J0812+3208 and log N
HDC = 14.83 ± 0.15 for z
C = 1.77637(2) and log N
HDD = 14.61 ± 0.20 for z
D = 1.77670(3) in the spectrum of Q1331+170. The measured HD/H2 ratio for three of these subsystems has been found to be considerably higher than its values typical of clouds in our Galaxy.We
discuss the problem of determining the primordial deuterium abundance, which is most sensitive to the baryon density of the
Universe Ωb. Using a well-known model for the chemistry of a molecular cloud, we have estimated the isotopic ratio D/H=HD/2H2 = (2.97 ± 0.55) × 10−5 and the corresponding baryon density Ωb
h
2 = 0.0205−0.0020+0.0025. This value is in good agreement with Ωb
h
2 = 0.0226−0.00060.0006 obtained by analyzing the cosmic microwave background radiation anisotropy. However, in high-redshift clouds, under conditions
of low metallicity and low dust content, hydrogen may be incompletely molecularized even in the case of self-shielding. In
this situation, the HD/2H2 ratio may not correspond to the actual D/H isotopic ratio. We have estimated the cloud molecularization dynamics and the
influence of cosmological evolutionary effects on it. 相似文献
14.
In the present paper we have considered the problem of determining the equilibrium structure of differentially rotating stars in which the angular velocity of rotation varies both along the axis of rotation and in directions perpendicular to it. For this purpose, a generalized law of differential rotation of the type
2 =b
0+b
1
s
2+b
2
s
4+b
3
z
2+b
4
z
4+b
5
z
2
s
2 (here is a nondimensional measure of the angular velocity of a fluid element distants from the axis of rotation andz from the plane through the centre of the star perpendicular to the axis of rotation, andb's are suitably chosen parameters) has been used. Whereas Kippenhahn and Thomas averaging approach has been used to incorporate the rotational effects in the stellar structure equations, Kopal's results on Roche equipotentials have been used to obtain the explicit form of the stellar structure equations, which incorporate the rotational effects up to second order of smallness in the distortion parameters. The method has been used to compute the equilibrium structure of certain differentially rotating polytropes. Certain differentially rotating polytropes. Certain differentially rotating models of the Sun have also been computed by using this approach. 相似文献
15.
The stability of the origin of an autonomous Hamiltonian system is investigated when the system possesses a third or fourth-order resonance.H
2, the quadratic part ofH isH
2=n
i=1
i
J
i
and the resonance condition is n
i=1
k
i
i
where thek 0,i = 1, 2, ...,n are the natural or fundamental frequencies. It is shown that the only case in which the origin can be unstable is ifk
i0,i=1,2,...,n. The condition for instability is then given in terms of the coefficients of the higher order terms in the Hamiltonian. The transfer of energy between modes is also investigated when a near-resonant condition exists. 相似文献
16.
The Cli line 8375.943 (4s 4P5/2 – 4p 4D7/2) is identified in the solar spectrum. This is the first identification of a chlorine line in solar spectrum. The measured equivalent width (W
= 0.8 mÅ) corresponds to an abundance log N(Cl) = 5.65 on the scale log N(H) = 12.00. 相似文献
17.
The estimates of the population of excited vibrational states of the CO2 molecule and of the rate of radiative cooling of the atmosphere in the 15-m CO2 band are given for the nighttime mesosphere and thermosphere of Mars. For the first time, these estimates are made (1) with allowance for the overlap of lines in the 15-m band; (2) for a wide set of vibrational states of seven isotopes of the CO2 molecule, which was used earlier in the solution of a similar terrestrial problem; and (3) using the rate constant for quenching of the CO2(0110) state in collisions with oxygen atoms, which has been recently measured for low temperatures by Khvorostovskaya et al. (2002). The main results are as follows. 1. The approximation of isolated lines provides a satisfactory accuracy of determining the radiative cooling rate and overestimates vibrational temperatures of the states of the 2 mode by no more than 3 K for the 12C16O2 molecule and by no more than 2 K for low-abundant isotopes of the CO2 molecule. 2. A reasonably high accuracy of estimating the cooling rate can be achieved by taking into account only fundamental vibrational transitions in 12C16O2, 13C16O2, 16O12C18O, and 16O12C17O molecules and the hot transitions 22 2 and 32 22 in the 12C16O2 molecule. 3. The vertical profile of the total rate of radiative cooling displays two peaks. The maximum near a height of 130 km is very sensitive to temperature and to the ratio of the mixture for oxygen in the atmosphere. 相似文献
18.
The equation of transfer for interlocked multiplets has been solved exactly by the method used by Busbridge and Stibbs (1954) for exponential form of the Planck functionB
v
(T)=b
0+b
1
e
–. 相似文献
19.
We report multifrequency observations of storm continuum and other radio bursts. Based on their positional study and their correlation with other coronal and photospheric features, we deduce that the storm source is located in the magnetic field lines lying above a single bipolar active region. Energetic electrons trapped in the magnetic structures above the spots must be responsible for the storm radiation. We show that spontaneous emission of Langmuir waves by anisotropic distributions can explain both storm continuum and bursts self-consistently. Whenever the collisional damping (
c
) is more than the growth (-
A
), there is a steady emission responsible for the continuum, and whenever
c
= -
A
(which may be satisfied randomly) there is a sudden jump in T
b
giving rise to bursts. The number density of energetic particles required to explain the storm continuum at 73.8, 50, and 30.9 MHz frequencies is estimated to lie in the limits n
b
/n
e
10–10–10–9 in the context of the present observations. The brightness spectrum of the storm continuum is computed and compared with observations.On leave from Indian Institute of Astrophysics, Bangalore 560034, India. 相似文献
20.
Huseyin Alkan 《Astrophysics and Space Science》1978,58(2):453-475
In the present paper
n
0
, for occulation and transit eclipses of partial phases, are evaluated numerically by means of the Runge-Kutta methods. Section 2 contains the required differential equations of
n
0
with respect to the modulusX orC, and Section 3 includes the numerical method of the solutions of these differential equations. Theoretical values of
0
0
and
1
0
, with corresponding values ofC, are also added in this section. 相似文献