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1.
The impact theory of spectral line broadening is used to obtain complete profiles for radio recombination lines perturbed by electron and proton impact. The collisions can be divided into two types: inelastic, where transitions take place between hydrogen levels with different principal quantum number n and elastic, where the transitions are only between degenerate levels for a particular value of n. The widths of the radio lines are essentially determined by inelastic electron collisions and elastic proton collisions with the emitting hydrogen atom occupying either the upper or lower levels of the line.Here, earlier work is extended to examine the contribution from proton collisions to the line width in more detail, and it is shown that the trends in the behaviour of the widths again confirm previous results.  相似文献   

2.
The CCD spectra taken with echelle spectrographs of the 2-m telescope of the Shemakha Astrophysical Observatory of the National Academy of Sciences of Azerbaijan and the 1-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences are used to study the line profile variations in the spectrum of the hot supergiant 55Cyg. The variability of the radial velocity and profiles of the lines of heavy elements is shown to be due to radial pulsation type motions. The corresponding variations for He I lines are due to nonradial pulsations. In the case of the H β and H α lines the pattern and behavior of variations differ for different observing periods. The variability of these lines is mostly due to the photometric and positional variability of the absorption and emission components of their profiles. The profiles of these lines show additional emission components, which move from the blue toward the red line wing. Such a behavior is indicative of the clumpy structure of the stellar envelope.  相似文献   

3.
In the Coudé focus of the 2 m RCC telescope at the National Astronomical Observatory of the Bulgarian Academy of Science 47 spectrograms covering the range from 3500 to 4900 Å (about 1400 Å) with a reciprocal dispersion of 9 Å mm–1 and a spectral resolution of 0.18 Å were obtained. The photometric and position behaviour of Balmer lines were investigated over a long time-scale, i.e. March 1981 to August 1982.The hydrogen line profiles were rectified in the way discribed by de Groot (1969). It is found that the absorption consists of three and sometimes four components. Their position behaviour may be expalined by the existence of two kinds of shells: pulsating and steadily expanding, and it is quite possible that shells of the first type may become shells of the second type in the outer parts of the P Cyg envelope.The total emission and absorption equivalent widths of the H11, H9, and H lines change with conspicuous minima and maxima. The amplitude of these variations increases with decrease in the upper quantum number. For example,W tot abs change by about 38% for H and 22% for H9.Our data suggest a periodic change in the radial velocities, intensity of each separate absorption component, total equivalent widths and profiles.  相似文献   

4.
A number of high resolution and high signal-to-noise ratio spectra of mildly metal-poor stars were obtained with the coudé echelle spectrograph attached to the 2.16m telescope at Xinglong Observation Base of Beijing Astronomical Observatory. The spectra of seven mildly metal-poor stars were processed with the MIDAS software package, and the equivalent widths of their spectral lines were measured. The measured equivalent widths together with an error analysis are presented.  相似文献   

5.
This is a study of optical emission lines of the nucleus of the Seyfert galaxy NGC 3227. This work is based on 53 spectrograms obtained with the 6-m telescope at the brightness maximum of this galactic nucleus on January 12–15, 1977. A set of profiles of the hydrogen Hα, and Hβ lines and the equivalent widths (EWλ) of six emission lines and blends averaged over series of observations are presented. Broadening of the hydrogen line profiles was observed over the three days. At a level of 0.50 times the peak brightness the hydrogen line profiles were broadened by 12%, 35%, and 44%, respectively. The broadening of the Hβ line was accompanied by a reduction in its equivalent width (EW ; ). It is suggested that a flare was observed in the nucleus of the galaxy on a time scale of 3 days, possibly caused to a shock wave in long-lived flows from the galaxy nucleus. __________ Translated from Astrofizika, Vol. 49, No. 4, pp. 499–510 (November 2006).  相似文献   

6.
The density matrix equations of highly excited carbon are analytically solved as functions of line number and temperature. Allowing for the series of the impact approximation theory and quadrupole interaction potential, the line widths are found with the theoretical error less than 0.06 in the range of temperatures T e = 25 − 100 K. To determine the medium temperature and density by using the experimental values of line widths, the Doppler, radiational and impact broadening are calculated for the lines with the principal quantum numbers n > 300. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

7.
Sixty-two spectrograms of the supergiant P Cyg, obtained with the Coudé spectrograph of the 2 m RCC telescope at NAO (National Astronomical Observatory, Bulgaria) were used in order to study the behaviour (we mean the displacements of the absorption components only) of the Hei spectrum of this star. Twelve lines from four series (23 P 0–n3S, 23P0 –n 3 D, 2 1 P 0 –n 1 D, and 21 S–n 1 P 0) were examined. It was established that all observed cases can be reduced to a few (three or four) which are typical. These cases are stated in the form of the comparison between the hydrogen and helium lines. All profiles were rectified and their complex structure was taken into consideration. The fixed peculiarities were explained by an optical depth effect.  相似文献   

8.
A high resolution spectrum of a sunspot umbra is used for identification of rotational lines due to (0, 0) band of the A 2Π–X 2Σ+ system and (0, 0), (1, 1), and (2, 2) bands of the B 2Σ+–X 2Σ+ system of the molecule SrF. The published sunspot umbral spectrum obtained with Fourier Transform Spectrometer and solar telescope of National Solar Observatory/National Optical Astronomy Observatory at Kitt Peak was used for the study. The new identification of more than 200 SrF lines in the umbral spectrum confirms that this molecule accounts for the majority of lines in the spectral range 15050 to 15360 cm−1 and 17240 to 17300 cm−1. Equivalent widths have been measured for well-resolved lines of these bands and the effective rotational temperatures have been estimated for which the presence is confirmed.  相似文献   

9.
Spectral observations of the flare star EV Lac made on the 2.6-m telescope at the Byurakan Observatory in 2000–2002 are reported. A powerful flare was detected and it was possible to follow the variation in the equivalent widths of the Hα and Hβ lines, both during the flare and during the quiescent phase of the star. It is shown that the profiles and equivalent widths of the lines underwent substantial changes. The equivalent widths of these emission lines reached a maximum roughly 40 min after the flare maximum. __________ Translated from Astrofizika, Vol. 49, No. 4, pp. 573–583 (November 2006).  相似文献   

10.
Using the solar tower telescope of Nanjing University, we observed the two large loop prominence groups of 1982 Dec. 20 and 1983 Feb. 9. Hα photographs and spectra around the Hα and H and K lines were obtained simultaneously. From these data, we derived a line of sight velocity distribution, which agrees perfectly with the distribution for matter falling freely without viscosity. From the widths of the Hα and the K lines, we found the loop material to have a uniform kinetic temperature and a turbulent velocity that increases with height. From the central intensities of the lines we derived a density of n(H) ? 1.3 ? 2.6 × 1010cm?3. A possible mechanism of the formation of loop prominence groups and their relation with flares are discussed.  相似文献   

11.
During the total eclipse of ε Aur, 18 spectra in the Hα region were taken in rapid succession on 1983 March 9, and 6 spectra on March 10, with the Reticon at the Coudé focus of the McDonald Observatory 2-metre telescope. The data were processed and plotted by computer. Variations on short time-scales were observed in the radial velocities of the metallic lines and Hα. The radial velocities of individual metallic lines are between 3 and 16 km/s more negative than calculated from the orbital elements. The Hα has 3 emission features with equivalent widths 300 mÅ, 54 mÅ and 1 mÅ and 1 absorption feature with an equivalent width of 1800 mÅ. The profile and the equivalent widths changed only slightly while substantial variations occurred on the blue side of the two stronger emission features. The radial velocities of the emission features are about ?60, +12 and +57 km/s; that of the absorption component is +20 km/s. The radial velocity of the strongest emission feature also varies, but by much smaller amounts than the metallic lines and the variation appears to be periodic. A model in which the secondary is a B-star surrounded by hot, active clouds is proposed.  相似文献   

12.
Two quiescent solar prominences were observed in July 2000 from SUMER aboard SOHO and from the two German solar telescopes at Tenerife. Two‐dimensional images taken at the VTT simultaneously in the spectral lines Hβ at 4862 Å and Ca II at 8542 Å show no significant spatial variation of their pressure‐sensitive emission ratio. Slit spectra of the Ca II 8542 Å and He I 10830 Å lines obtained at the Gregory‐Coudé telescope yield 8000 K < Tkin < 9000 K and 3 km/s < Vn–th < 8 km/s. Among the various spectral ranges observed with SUMER, we first investigate the Lyman emission lines, which were fitted by Gaussians yielding reliable spectral radiances and line widths for the series members 5 < k < 18. A determination of the level population gives for the lower series members a Boltzmann temperature of 60 000 K, the higher members being over‐populated. This temperature indicates an origin of the Lyman lines from hot surroundings of the cool prominence body seen in the ground‐based data; this also holds for the ‘hotter’ SUMER lines.  相似文献   

13.
We present the optical observations of the AM Herculis system EU UMa (=RE1149+28) carried out in February 1993 with a TV scanner and a photometer (NEPh) at the secondary focus of the 6-m Special Astrophysical Observatory telescope. Spectroscopy with a time resolution of 300 s and a spectral resolution of 2 Å in the wavelength range ≈3950–4950 Å is used to analyze the variability of emission-line profiles, equivalent widths, central intensities Rc, and radial velocities with orbital phase. We determined the orbital period of the system from line radial-velocity measurements, 90.0±0.2 min. The emission-line profiles are highly variable. The Hβ and He II 4686 Å lines exhibit P Cyg profiles at selected phases. The spectral-line parameters were found to vary significantly on time scales from 5 to 15 min. The possible causes of the detected spectroscopic variability are discussed.  相似文献   

14.
Results from a spectrophotometric study of 21 galaxies with UV excess are presented. The half widths (FWHM) and equivalent widths of observed spectrum lines of these galaxies, as well as the relative intensities of the emission lines observed in the spectrum of the galaxy Kaz243, are determined. It is conjectured that the latter galaxy has the properties of an Sy2 type galaxy. The electron densities and masses of the gaseous components are found for 15 galaxies, along with the masses of 8 galaxies for which the ratio M/L has been calculated. It is shown that the spectral structures of these galaxies do not depend on whether they are members of physical systems or are isolated.  相似文献   

15.
For nearly two decades, the aperature synthesis telescope known as the Very Large Array (VLA) has been providing a wealth of data on all types of astronomical objects. This telescope fills the need for more powerful and more sensitive instruments to gather data on a vast range of plasma phenomena in astrophysical settings. Currently the VLA is capable of observing at eight radio frequency bands (four corresponding to important spectral lines) with sensitivities on the order of 10–29 Wm –2 Hz –1, or 10–3 Jansky (1 mJy), and noise levels ten times lower. This paper describes the VLA and its capabilities, and describes how researchers interested in plasma astrophysics can use the instrument.  相似文献   

16.
Based on 24 high-resolution echelle spectrograms of the Wolf-Rayet star HD 192163 taken in 2005–2007 at the Cassegrain focus of the 2-m Zeiss-2000 telescope at the Shemakha Astrophysical Observatory (National Academy of Sciences of Azerbaijan), we have investigated the profiles of five emission lines: He II 4859, He II 5411, CIV 5808, He I 5875, (He II + Hα) 6560. We have analyzed the echelle spectrograms using the DECH20 code. Various emission line parameters have been determined: the equivalent widths, radial velocities, central intensities, and FWHMs. The violet wing of the He II + Hα emission band has been found to be variable (from 6496 Å to 6532 Å). Significant differences in the equivalent widths and radial velocities of the He II + Hα emission band in 2005 and 2007 were revealed. This can be a manifestation of long-term variations in the star HD 192163. We have confirmed that HD 192163 belongs to the WN6 spectral subtype.  相似文献   

17.
We determine abundances from the absorption spectrum of the magnetic Herbig Ae star HD 190073 (V1295 Aql). The observations are primarily from HARPS spectra obtained at a single epoch. We accept arguments that the presence of numerous emission lines does not vitiate a classical abundance analysis, though it likely reduces the achievable accuracy. Most abundances are closely solar, but several elements show departures of a factor of two to three, as an earlier study has also shown. We present quantitative measurements of more than 60 emission lines, peak intensities, equivalent widths, and FWHM's. The latter range from over 200 km s–1(Hα, He D3) down to 10–20 km s–1(forbidden lines). Metallic emission lines have intermediate widths. We eschew modeling, and content ourselves with a presentation of the observations a successful model must explain. Low‐excitation features such as the Na I D‐lines and [O I] appear with He I D3, suggesting proximate regions with widely differing Te and Ne as found in the solar chromosphere. The [O I] and [Ca II] lines show sharp, violet‐shifted features. Additionally, [Fe II] lines appear tobe weakly present in emission (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

18.
Heights of formation of lines that do not exhibit Zeeman splitting are calculated using an LTE, partial non-LTE, and full non-LTE approach. Non-magnetic (g=0) lines are valuable for velocity investigations in quiet-Sun magnetic field regions, and a knowledge of their formation heights is useful for obtaining three dimensional velocity profiles in these regions. Presently at Sacramento Peak Observatory. Operated by the Association of Universities for Research in Astronomy, Inc., under contract with the National Science Foundation.  相似文献   

19.
We have used the SPO tower telescope and echelle spectrograph to study differences in the profiles of three Fei lines, between magnetic network and cells. Ca K slit-jaw pictures were used to identify the network and cell areas, and mean network and cell profiles were computed from digitized spectra for the g = 0 lines 4065, 5434, and the g = 1.5 line 5233. The profile bisectors show that the wings of all three lines are red-shifted in the network by between 75–200 m s–1 relative to the cell profiles. But the redshift decreases in the line core and becomes less than the standard error of 20 m s–1 near the line core minimum. This disappearance of the redshift at the cores of all 3 lines formed over the height range 250–500 km above 0.5 = 1, argues against a steady downflow at supergranule boundaries. We show that such red-shifted wings and a relatively unshifted core can result if granular convection is suppressed near the network flux tubes, without implying any downflow in the vicinity of these flux tubes. Our results also indicate that searches for large-scale convective velocity patterns should measure shifts of the line core, rather than the line wings which appear to be very sensitive to inhomogeneities in granule structure.Visiting Astronomers, Sacramento Peak Observatory.  相似文献   

20.
We analyze and discuss the properties of decameter spikes observed in July?–?August 2002 by the UTR-2 radio telescope. These bursts have a short duration (about one second) and occur in a narrow frequency bandwidth (50?–?70 kHz). They are chaotically located in the dynamic spectrum. Decameter spikes are weak bursts: their fluxes do not exceed 200?–?300 s.f.u. An interesting feature of these spikes is the observed linear increase of the frequency bandwidth with frequency. This dependence can be explained in the framework of the plasma mechanism that causes the radio emission, taking into account that Langmuir waves are generated by fast electrons within a narrow angle θ≈13°?–?18° along the direction of the electron propagation. In the present article we consider the problem of the short lifetime of decameter spikes and discuss why electrons generate plasma waves in limited regions.  相似文献   

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