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1.
Solar wind speeds (SWSs) estimated by interplanetary scintillation (IPS) observations during Carrington rotation 1753 are projected onto the so-called source-surface of 2.5 solar radii along magnetic field lines in interplanetary space. The following two working hypotheses are examined from different points of view: (1) The SWS is a weighted mean along the line of sight to a radio source; the weight for the SWS depends on the distance from theP-point, the closest approach to the Sun on the line of sight. (2) The weighting function has a very sharp peak at theP-point, so that the SWS shows a real solar wind speed at theP-point. In both the two cases, the SWSs projected onto the source surface are further projected onto the photosphere along magnetic field lines in the corona. Footpoints of these field lines are inferred as photospheric source regions of the solar wind. The intensity of the Hei (1083 nm) absorption line (HEI) in the chromosphere corresponding to these photospheric sources is interpolated from observational data. The weighted mean of the HEI is calculated in case 1. The HEI corresponding to theP-point is used in case 2. The SWS is compared with the HEI in both the two cases. It is found that the correlation between the SWS and the HEI is better in case 2 than in case 1. It is further inferred by correlation analysis between the SWS and the HEI that the solar wind is accelerated within 27 solar radii on average. Although the data examined in this paper were limited to just one solar rotation, these results suggest that the SWS estimated by the IPS technique corresponds to the solar wind speed near theP-point and the weighting function along the line of sight may have a very sharp peak near theP-point.  相似文献   

2.
We describe how the ISO-SWS (Infrared Space Observatory – Short Wavelength Spectrometer) software packages detect various glitch events i.e. high energy particle hits effecting the SWS detectors. A rough classification of glitch types is given. The events cause an instantaneous change in the slope of the SWS detector read outs followed by a distortion of the further samples, so called glitch tails. As a consequence the S/N ratio and photometric accuracy are reduced.Different strategies, how to remove the resulting distortion of the detectorread-out-ramp after a hit, are presented. The methods of the basic SWS software packages, the Pipeline and Interactive Analysis, will be discussed. The Pipeline has to treat glitch effects automatically. The Interactive Analysis system provides the user with a comfortable Graphical User Interface (GUI) for Trend Analysis, detailed analysis of certain glitches and the testing of new algorithms.  相似文献   

3.
Hakamada  Kazuyuki  Kojima  Masayoshi 《Solar physics》1999,187(1):115-122
The synoptic map of the solar wind speed (SWS) estimated by the computer-assisted tomography (CAT) method with interplanetary scintillation observations is constructed for the 1909 Carrington rotation. A similar synoptic map of expansion rate (RBR) of the coronal magnetic field calculated by the so-called 'potential model' with the photospheric magnetic field is also constructed under the radial field assumption (RF model). These maps consist of 64800 (180×360) data points of equal area. We examine for the first time relations between the SWS estimated by the CAT technique and the RBR calculated by the RF model. A highly significant correlation is found between the SWS and the RBR. A simple correlation coefficient is about –0.72; that is, high-velocity winds emanate from photospheric areas corresponding to a low expansion rate of the coronal magnetic field, and low-velocity winds emanate from photospheric areas of high expansion rate. This result suggests that there is some acceleration mechanism relating to the coronal field expansion.  相似文献   

4.
El-Borie  M.A. 《Solar physics》2002,208(2):345-358
The ultra-low frequency power spectra (from 1 nHz to 10 Hz) for the solar wind ion density (N) and speed (SWS) measurements taken near 1 AU, have been examined during the period 1973–2000. Although the spectrum shows remarkable peaks at the wavelengths 0.5, 0.7, 1.0, 1.3 years, additional significant peaks of 2.6 yr and 5.6 yr for N and 9.6 yr for SWS are also found. Possible causes are discussed. The 9.6-yr period is not related to the period of the solar activity cycle, but there is some indication of an association with the coronal hole variations in the southern hemisphere of the Sun. The averages of solar wind ion density showed a periodic variation with three nearly equal peaks at intervals of 5.1±0.2 yr. The long-term enhancements in SWS reflect nearly stable variations and a continuously-existing feature in the heliosphere. The observed long periodicities in both N and SWS spectra may be strongly related to, or organized by, the observed variations in the coronal hole areas between northern and southern hemispheres of the Sun. The timing of the maximum peaks in solar ion densities and speeds spectrum is predicted.  相似文献   

5.
The Infrared Space Observatory (ISO) Short-Wavelength Spectrometer (SWS) spectra of 10 Be stars are presented. It can be seen that the Be stars show a diversity in their ISO SWS01 spectral classifications by Kraemer et al., from naked stars, stars associated with dust, stars with warm dust shells, stars with cool dust shells to very red sources. In addition, the Brc/HI(14-6) line flux ratio derived for the sample stars is compared with that of P Cyg, and it is found that the line ratio of Be stars which were investigated show not only lower values as suggested by Waters et al., but also larger values. Therefore, the line ratio cannot he used to judge whether a star is a Be star or not.  相似文献   

6.
Overall SEDs based on ISO SWS observations show fair agreement with photospheric model predictions for red (super)giant stars. However, some details of molecular spectra cannot be explained by a photospheric origin. In particular, fine structure in the H2O 2.7 μm band can be clearly resolved by the SWS and is identified in an early M giant, whose photosphere will never produce H2O. This is definite evidence for H2O of non-photospheric origin in an early M giant. Also, the observed H2O and CO2 bands in a late M giant are too strong to be explained by a photospheric origin alone. Further, the H2O 2.7 μm band is found in four early M supergiants in the h + χ Persei clusters (three of which show UIRs) and is especially strong in the M4 supergiant S Per (which also shows a highly peculiar SED). Thus, against a belief that H2O is found only in the latest M giants such as Miras, the SWS has revealed the presence of H2O in a wider region of the HR diagram. The origin of this H2O is unknown but is probably in a non-photospheric extra envelope. Such a H2O envelope appears to be a general feature through early M (super)giants to cool supergiants such as S Per, where the envelope has finally developed to be optically thick. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

7.
Observations of 5 stellar sources with unusual characteristics of IRAS Low Resolution Spectra were made with the SWS on ISO. Observed stars are 4 late-type stars with silicate bands and one planetary nebula. Their IRAS LRS contain somewhat unusual features in respect of the 10/18 μm intensity ratio or narrow emission feature from unknown molecular bands. Some narrow unusual features are confirmed by ISO SWS01 spectra but the broad features were turned out to be false. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

8.
We discuss silicate emission profiles observed with the ISO SWS and ground-based IR observations in a population of intermittently embedded Herbig Ae/Be stars which are viewed edge-on to their polarimetrically identified dust and gas disks. The ISO SWS observations confirm the lack of a simple correlation between system age and the profile shape. Comparison with laboratory silicates suggests that much of the observed variation is due to different annealing histories of the grains. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

9.
For this paper, we collected all infrared carbon stars (IRCSs) known so far from the literature and identified the 2MASS counterparts of all IRCSs. Using 2MASS, IRAS and ISO SWS data, we investigate the infrared properties of IRCSs. We find that the infrared colors and temperatures of IRCSs—not only in the IRAS region but also in the near infrared—are between those for visual carbon stars and extreme carbon stars. The results in this paper strongly support the suggestion that the sequence of visual carbon stars → infrared carbon stars → extreme carbon stars is the evolutionary sequence in the AGB phase for carbon-rich stars. In addition, using the ISO SWS data, we find that an evolutionary sequence also exists within the IRCS stage.  相似文献   

10.
We present the spectra of 5 OH/IR stars observed with the Short Wavelength Spectrometer (SWS) on board the Infrared Space Observatory (ISO). The spectra are dominated by dust features, both in the amorphous and crystalline state and illustrate the influence of the mass loss rate on the observed spectral features. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

11.
Thirteen synoptic maps of expansion rate of the coronal magnetic field (CMF; RBR) calculated by the so-called ‘potential model’ are constructed for 13 Carrington rotations from the maximum phase of solar activity cycle 22 through the maximum phase of cycle 23. Similar 13 synoptic maps of solar wind speed (SWS) estimated by interplanetary scintillation observations are constructed for the same 13 Carrington rotations as the ones for the RBR. The correlation diagrams between the RBR and the SWS are plotted with the data of these 13 synoptic maps. It is found that the correlation is negative and high in this time period. It is further found that the linear correlation is improved if the data are classified into two groups by the magnitude of radial component of photospheric magnetic field, |Bphor|; group 1, 0.0 G ≦ |Brpho| < 17.8 G and group 2, 17.8 G ≦ |Brpho|. There exists a strong negative correlation between the RBR and the SWS for the group 1 in contrast with a weak negative correlation for the group 2. Group 1 has a double peak in the density distribution of data points in the correlation diagram; a sharp peak for high-speed solar wind and a low peak for low-speed solar wind. These two peaks are located just on the axis of maximum variance of data points in the correlation diagram. This result suggests that the solar wind consists of two major components and both the high-speed and the low-speed winds emanating from weak photospheric magnetic regions are accelerated by the same mechanism in the course of solar activity cycle. It is also pointed out that the SWS can be estimated by the RBR of group 1 with an empirical formula obtained in this paper during the entire solar activity cycle.  相似文献   

12.
We present a trend analysis of the ISO-SWS detector performance and a study of the space radiation effects on the SWS detectors. In particular, dark currents, dark current noise and detector responses have been checked as a function of time through the mission and as a function of time in arevolution. The results show that these parameters were stable during the mission in all bandsbut for band 3 (Si:As). Dark currents and responses were found to be higherin the first hours following the start of the science window,especially in band 2 (Si:Ga). We have studied the impacts of cosmic rays and radiation belt particles on the SWS detectors, as well as of the only large solar proton event on November 6, 1997,that occurred during the ISO mission (operated during solar minimum).The observed glitch rates in all SWS bands are found to be between 2 and4 times higher than the value predicted by the CREME96 model for the cosmic ray flux in the period considered. The bands that registered the highest glitch rates showed also a correlation with the electron fluxes measured on theGOES 9 spacecraft. From the distribution of glitchheights (voltage jumps in the detector signal), we have derived the deposited energy distributions of the particles hits. Our results lead to the conclusion that secondaryparticles produced in the shield and the detectors contributed at least as much as cosmic rays to the observed glitch rate. The effects on the detectors of the November 6, 1997 event, which caused that all observationsin a revolution were declared failed, are described in detail.  相似文献   

13.
We have observed ten carbon stars with different mass-loss rates using the Short Wavelength Spectrometer (SWS) on board ISO. We found that not only the spectral energy distribution and the dust features, but that also that the strength and/or shape of molecular absorption features in the infrared spectrum varies with the near-infrared color temperature, i.e. with the thickness of the circumstellar envelope. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

14.
We present ISO observations of bright, high-mass southern starforming regions with the Short Wavelength Spectrometer (SWS) and Long Wavelength Spectrometer (LWS). The selected targets show a range of pre-main sequence evolutionary phases. Whereas some objects still show interstellar ice features, the most evolved objects are coincident with ultra-compact HII regions and show strong emission lines from atomic species and polycyclic aromatic hydrocarbons (PAHs). We discuss the ISO spectra between 2.5 - 200 μm of selected southern star-forming regions in the context of their evolution. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

15.
We present our analysis of four molecular outflows from Class 0 (Cep E,L 1448) sources and higher mass objects (Cep A, DR 21). The emission line spectra of these outflows were observed in the mid- and far-infrared using the spectrometers (SWS, LWS) and the camera (ISOCAM) aboard the ISO satellite. We interpret the spectra using J- and C-type bow shock models and infer properties of both the outflow and surrounding gas. We find C-type bows with a shape parameter of s = 1.4 as the best interpretation of the measured line fluxes, independent of the object. The emission is partly caused by fluorescence.  相似文献   

16.
Relationships between solar wind speed and expansion rate of the coronal magnetic field have been studied mainly by in-ecliptic observations of artificial satellites and some off-ecliptic data by Ulysses. In this paper, we use the solar wind speed estimated by interplanetary scintillation (IPS) observations in the whole heliosphere. Two synoptic maps of SWS estimated by IPS observations are constructed for two Carrington rotations CR 1830 and 1901; CR 1830 starting on the 11th of June, 1990 is in the maximum phase of solar activity cycle and CR 1901 starting on the 29th of September, 1995 is in the minimum phase. Each of the maps consist of 64800 (360×180) data points. Similar synoptic maps of expansion rate of the coronal magnetic field (RBR) calculated by the so-called potential model are also constructed under a radial field assumption for CR 1830 and CR1901. Highly significant correlation (r=–0.66) is found between the SWS and the RBR during CR1901 in the solar minimum phase; that is, high-speed winds emanate from photospheric areas corresponding to low expansion rate of the coronal magnetic field and low speed winds emanate from photospheric areas of high expansion rate. A similar result is found during CR 1830 in solar maximum phase, though the correlation is relatively low (r=–0.29). The correlation is improved when both the data during CR 1830 and CR 1901 are used together; the correlation coefficient becomes –0.67 in this case. These results suggest that the correlation analysis between the SWS and the RBR can be applied to estimate the solar wind speed from the expansion rate of the coronal magnetic field, though the correlation between them may depend on the solar activity cycle. We need further study of correlation analysis for the entire solar cycle to get an accurate empirical equation for the estimation of solar wind speed. If the solar wind speed is estimated successfully by an empirical equation, it can be used as an initial condition of a solar wind model for space weather forecasts.  相似文献   

17.
We present Infrared Space Observatory (ISO)Short Wavelength Spectrometer (SWS) observations for 16Wolf–Rayet ([WR]) planetary nebulae (PNe) in the range from 2.4 to16.5 m with the aim of analyzing the dust features present inthis group of objects. We have found that Policyclic AromaticHydrocarbon (PAH) molecular bands are present in most of the observed[WR] planetary nebulae with clear exception for K 2–16 among latetype [WC] stars.  相似文献   

18.
A sample of 323 Ultraluminous IRAS galaxies (ULIRGs) has been correlatedwith the ROSAT All-Sky Survey and ROSAT public pointed observations.22 objects are detected in ROSAT survey observations, and 6 ULIRGs aredetected in addition in ROSAT public pointed observations. The detection is basedon a visual inspection of the X-ray contour maps overlaid on optical imagesof ULIRGs taken from the Digitized Sky Survey.Simple power law fits were used to compute the absorption-correctedfluxes of the ROSAT detected ULIRGs. The ratio of the soft X-ray flux to thefar-infrared luminosity is used to estimate the contributionfrom starburst and AGN emitting processes. These results are comparedwith the ISO SWS ULIRG diagnostic diagram.  相似文献   

19.
Compared to the pre-launch measurements, the in-orbit noise levels ofthe Short Wavelength Spectrometer (SWS) detectors show a significantincrease, considerably lowering the overall sensitivity. Cosmic rayimpacts on the detectors and/or on the instrument electronics play animportant role in the noise levels and consequently many observations offaint sources are affected by this increased noise. However, by takingadvantage of the high read-out frequency of 24 Hz and the redundanciesprovided by the observing strategy, it is possible to significantlyimprove the quality of the data. Here, we present the concept ofself-calibration and additional algorithms, which are successfullyapplied to recover the weak signals of molecular hydrogen lines undetectable in a standard data reduction.  相似文献   

20.
Observations of emissivity features of 10 Hygiea have been made for the first time in the relatively unexplored thermal-infrared wavelength region with the ISO (Infrared Space Observatory) satellite. Spectrophotomer (PHT-S) and short wavelength spectrometer (SWS) spectra of 10 Hygiea, obtained at 5.8-11.6 and 7-45 μm, respectively, are presented. In order to remove the thermal emission continuum, an advanced thermo-physical model has been applied to the observational data. To better interpret the spectral features above the thermal emission continuum, we compared the ISO observations with laboratory spectra available in the literature. Several laboratory experiments on minerals and meteorites have been performed to complete the analysis and to study the spectral behavior at various grain sizes. A possible spectral similarity with CO carbonaceous chondrites at small grain size is demonstrated.  相似文献   

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