共查询到20条相似文献，搜索用时 15 毫秒
1.
Based on spectropolarimetric observations Seyfert 2 (Sy2) galaxies are generally divided into two populations. Some Sy2s show polarized broad emission lines (PBLs) which is an evidence for the hypothesis of the Unified model while others do not. In order to determine the properties of these two apparently different populations we compiled a sample of 66 Sy2 objects with and without detected PBLs. We used a (J − H) − (H − Ks) diagram based on 2MASS J, H, Ks magnitudes in 14 arcsec aperture, the F[OIII] emission line flux and the infrared emission flux FKs using the Ks filter. From the (J − H) − (H − Ks) diagram we determined that one third of the Sy2 objects with PBLs have a power-law infrared component which could be a result of both a non-thermal AGN component scattered by free electrons (or dust) and emission from hot dust near its sublimation temperature. The rest of the objects (with PBLs) are significantly dominated by a dust thermal re-emission. The Sy2s without PBLs show infrared emission dominated by a host galaxy stellar component and also by thermal dust re-emission. The Sy2s with PBLs tend to have a few times larger L[OIII] luminosities than those without. Following the median values of F[OIII]/FKs, it seems that this ratio is sensitive enough to separate our sample of Sy2 galaxies into two types - with and without PBLs. There are no Sy2s with PBLs having Eddington ratio below 10−3 which confirms the results of Nicastro et al. (2003). 相似文献
2.
In this study, we present long term photometric variations of the close binary system GO Cyg. Modelling of the system shows that the primary is filling Roche lobe and the secondary of the system is almost filling its Roche lobe. The physical parameters of the system are M1 = 3.0 ± 0.2M⊙, M2 = 1.3 ± 0.1M⊙, R1 = 2.50 ± 0.12R⊙, R2 = 1.75 ± 0.09R⊙, L1 = 64 ± 9L⊙, L2 = 4.9 ± 0.7L⊙, and a = 5.5 ± 0.3R⊙. Our results show that GO Cyg is the most massive system near contact binary (NCB). Analysis of times of the minima shows a sinusoidal variation with a period of 92.3 ± 0.5 yr due to a third body whose mass is less than 2.3M⊙. Finally a period variation rate of −1.4 × 10−9 d/yr has been determined using all available light curves. 相似文献
3.
This paper presents the results of spectroscopic and photometric observations of the early-type W UMa system V535 Ara. New high-resolution spectra were taken at the Mt. John University Observatory in 2007. Radial velocities and spectroscopic orbital elements of the system were determined by applying KOREL spectral disentangling. The resulting orbital elements were: a1sini = 0.0047 ± 0.0001 AU, a2sini = 0.0146 ± 0.0001 AU, M1sin3i = 1.85 ± 0.01 M⊙, and M2sin3i = 0.59 ± 0.01 M⊙. The components were found to be in synchronous rotation following examination of their disentangled Hγ line profiles. Four photometric data-sets (1966 BV, 1967 BV, HIPPARCOS and ASAS) were modeled using the Wilson-Devinney method. The model describes V535 Ara as an A sub-type W UMa type eclipsing binary which has a fill out factor of 0.22 in marginal contact configuration. The simultaneous solution of light and radial velocity curves gave the following absolute parameters: M1 = 1.94 ± 0.04 M⊙, M2 = 0.59 ± 0.02 M⊙, R1 = 2.09 ± 0.03 R⊙, R2 = 1.23 ± 0.02R⊙, L1 = 18 ± 3 L⊙ and L2 = 6 ± 1 L⊙. The distance to V535 Ara was calculated as 123 ± 20 pc using distance modulus with correction for interstellar extinction. 相似文献
4.
This paper presents the first analysis of spectroscopic and photometric observations of the eclipsing binary star WZ Hor. Observations of the system were made at the Mt. John University Observatory in 2007. Since the light contribution of the secondary component was merely 2-3% of the total light of the system in the optical wavelengths, the radial velocity of the primary component could only be determined using the cross-correlation method. A single-lined spectroscopic orbital solution of WZ Hor was obtained, and the BVRI light curves of the system and radial velocity curve of the primary component were analysed simultaneously using the Wilson-Devinney method. The results describe WZ Hor as a reverse Algol-like binary star with a detached configuration. The following absolute parameters of the components were also derived: M1 = 1.51 ± 0.03 M⊙, M2 = 0.66 ± 0.01 M⊙, R1 = 1.62 ± 0.02 R⊙, R2 = 0.66 ± 0.01 R⊙, L1 = 4.93 ± 0.64 L⊙ and L2 = 0.09 ± 0.02 L⊙. The distance to WZ Hor was calculated as 95 ± 8 pc using distance modulus with correction for interstellar extinction, in agreement with the HIPPARCOS value. 相似文献
5.
We present the results based on multiwavelength imaging observations of the prominent dust lane starburst galaxy NGC 1482 aimed to investigate the extinction properties of dust existing in the extreme environment. (B-V) colour-index map derived for the starburst galaxy NGC 1482 confirms two prominent dust lanes running along its optical major axis and are found to extend up to ∼11 kpc. In addition to the main lanes, several filamentary structures of dust originating from the central starburst are also evident. Though, the dust is surrounded by exotic environment, the average extinction curve derived for this target galaxy is compatible with the Galactic curve, with RV = 3.05, and imply that the dust grains responsible for the optical extinction in the target galaxy are not really different than the canonical grains in the Milky Way. Our estimate of total dust content of NGC 1482 assuming screening effect of dust is ∼2.7 × 105 M⊙, and provide lower limit due to the fact that our method is not sensitive to the intermix component of dust. Comparison of the observed dust in the galaxy with that supplied by the SNe to the ISM, imply that this supply is not sufficient to account for the observed dust and hence point towards the origin of dust in this galaxy through a merger like event.Our multiband imaging analysis reveals a qualitative physical correspondence between the morphologies of the dust and Hα emission lines as well as diffuse X-ray emission in this galaxy. Spatially resolved spectral analysis of the hot gas along outflows exhibit a gradient in the temperature. Similar gradient was also noticed in the measured values of metallicity, indicating that the gas in the halo is not yet enriched. High resolution, 2-8 keV Chandra image reveals a pair of point sources in the nuclear region with their luminosities equal to 2.27 × 1039 erg s−1 and 9.34 × 1039 erg s−1, and are in excess of the Eddington-limit of 1.5 M⊙ accreting source. Spectral analysis of these sources exhibit an absorbed-power law with the hydrogen column density higher than that derived from the optical measurements. 相似文献
6.
New photometry for the eclipsing binary BE Cephei was performed from 2008 to 2011. The light-curve synthesis indicates that it is a marginal-contact binary with a mass ratio of q = 2.340(±0.009) and a degree of contact of f = 6.9%(±2.3%). From the O − C curve, it is discovered that the orbital period changes show a sinusoidal curve superimposed on a downward parabola. The period and semi-amplitude of the cyclic variation are Pmod = 59.26(±0.52) yr and A = 0.d0067(±0.d0010), which may be possibly attributed to light-time effect via the presence of an unseen third body. The long-term period decreases at a rate of dP/dt = −4.84(±0.31) × 10−8 d yr−1, which may result from mass transfer from the more massive component to the less massive one, accompanied by angular momentum loss. With the period decreasing, the degree of contact will increase. Finally, the marginal-contact binary BE Cep may be evolving into a deep-contact configuration. 相似文献
7.
In this paper, we have used optical intra-day variability archive data to calculate the central black hole masses and Eddington luminosities for nine blazars: 3C 66A, AO 0235+164, S5 0716+714, PKS 0735+178, OJ 287, 1215+303, 1216−010, 1308+326, PKS 1510−089, Mrk 501 and BL Lac using intra-day variability timescales and periodicity (if present). The calculated central black hole mass of these nine blazars using intra-day variability timescales are found to be in the range of 1.22-25.30 × 107 M⊙ and corresponding Eddington luminosity in the range of 1.58-32.88 × 1045 erg s−1. The black hole mass and Eddington luminosity are in the range of 0.32-31.23 × 108 M⊙ and 1.23-31.20 × 1046 erg s−1, respectively when optical Doppler factor is taken into account. The comparison show, our estimated values of black hole mass are consistent with earlier reported values. Periodicity were present in two blazars OJ 287 and 1216−010 which give the central black hole mass of these blazars in the range of 1.32-14.6 × 107 M⊙ and corresponding Eddington luminosity in the range of 1.60-19.0 × 1045 erg s−1, respectively. 相似文献
8.
Yüksel Karata? 《New Astronomy》2012,17(1):22-33
We study the kinematics of the Galactic thin and thick disk populations using stars from the RAVE survey’s second data release together with distance estimates from Breddels et al. (2010). The velocity distribution exhibits the expected moving groups present in the solar neighborhood. We separate thick and thin disk stars by applying the X (stellar-population) criterion of Schuster et al. (1993), which takes into account both kinematic and metallicity information. For 1906 thin disk and 110 thick disk stars classified in this way, we find a vertical velocity dispersion, mean rotational velocity and mean orbital eccentricity of (σW, 〈VΦ〉, 〈e〉)thin = (18 ± 0.3 km s−1, 223 ± 0.4 km s−1, 0.07 ± 0.07) and (σW, 〈VΦ〉, 〈e〉)thick = (35 ± 2 km s−1, 163 ± 3 km s−1, 0.31 ± 0.16), respectively. From the radial Jeans equation, we derive a thick disk scale length in the range 1.5-2.2 kpc, whose greatest uncertainty lies in the adopted form of the underlying potential. The shape of the orbital eccentricity distribution indicates that the thick disk stars in our sample most likely formed in situ with minor gas-rich mergers and/or radial migration being the most likely cause for their orbits. We further obtain mean metal abundances of 〈[M/H]〉thin = +0.03 ± 0.17, and 〈[M/H]〉thick = −0.51 ± 0.23, in good agreement with previous estimates. We estimate a radial metallicity gradient in the thin disk of −0.07 dex kpc−1, which is larger than predicted by chemical evolution models where the disk grows inside-out from infalling gas. It is, however, consistent with models where significant migration of stars shapes the chemical signature of the disk, implying that radial migration might play at least part of a role in the thick disk’s formation. 相似文献
9.
Xiong Ding-rong Zhang XiongZheng Yong-gang Huang Bang-rongMao Li-sheng Liu Wen-guang 《Chinese Astronomy and Astrophysics》2013
In this paper, we collect the redshift, bolometric luminosity, the full- width at half maximum of the Hβ emission line, the monochromatic luminosity at 5100 Å and the radio loudness for the sample of 117 quasars, including 20 radio-quiet quasars (RQQs) and 97 radio-loud quasars (RLQs). With the reverberation mapping method we calculate the black hole mass and Eddington ratio for this sample, as well as the radio luminosity from the total 5 GHz ?ux density. By analyzing the correlations among them, we obtain the following conclusions: (1) The black hole mass has weak correlations with the bolometric luminosity, radio loudness and radio luminosity for the RQQs, and has strong correlations with the bolometric luminosity, radio loudness and radio luminosity for the RLQs; (2) For the RQQs, the bolometric luminosity has weak correlations with the radio luminosity and 5 100 Å monochromatic luminosity, and for the RLQs, the bolometric luminosity has strong correlations with the radio luminosity and 5 100 Å monochromatic luminosity; (3) The RQQs and RLQs differ in the distributions of the black hole mass, emission line width and Eddington ratio. Based on these results, we suggest: the difference of emission line width between RQQs and RLQs is probably caused by the difference of black hole mass; the fundamental difference between RQQs and RLQs is caused by the difference of their intrinsic physical nature; the black hole mass, black hole spin, Eddington ratio, and host galaxy morphology are the important parameters to explain the origin of radio loudness and the double-peaked distribution; and the radio jet is closely related with the accretion rate of disk. 相似文献
10.
We have obtained spatially resolved spectra of Titan in the near-infrared J, H and K bands at a resolving power of ∼5000 using the near-infrared integral field spectrometer (NIFS) on the Gemini North 8 m telescope. Using recent data from the Cassini/Huygens mission on the atmospheric composition and surface and aerosol properties, we develop a multiple-scattering radiative transfer model for the Titan atmosphere. The Titan spectrum at these wavelengths is dominated by absorption due to methane with a series of strong absorption band systems separated by window regions where the surface of Titan can be seen. We use a line-by-line approach to derive the methane absorption coefficients. The methane spectrum is only accurately represented in standard line lists down to ∼2.1 μm. However, by making use of recent laboratory data and modeling of the methane spectrum we are able to construct a new line list that can be used down to 1.3 μm. The new line list allows us to generate spectra that are a good match to the observations at all wavelengths longer than 1.3 μm and allow us to model regions, such as the 1.55 μm window that could not be studied usefully with previous line lists such as HITRAN 2008. We point out the importance of the far-wing line shape of strong methane lines in determining the shape of the methane windows. Line shapes with Lorentzian, and sub-Lorentzian regions are needed to match the shape of the windows, but different shape parameters are needed for the 1.55 μm and 2 μm windows. After the methane lines are modeled our observations are sensitive to additional absorptions, and we use the data in the 1.55 μm region to determine a D/H ratio of 1.77 ± 0.20 × 10−4, and a CO mixing ratio of 50 ± 11 ppmv. In the 2 μm window we detect absorption features that can be identified with the ν5 + 3ν6 and 2ν3 + 2ν6 bands of CH3D. 相似文献
11.
We present the results of the high-resolution spectroscopic observations of the neglected binary system HD 194495 (B3 IV-V+B4 V). A combined analysis of three different photometric data set (Tycho BT and VT photometry, Hp-band data of Hipparcos and V-band data of ASAS3 photometry) and radial velocities indicates that the system has an orbital period of 4.90494 ± 0.00005 days and an inclination of 69 ± 1 degrees. This solution yields masses and radii of M1 = 7.57 ± 0.08 M⊙ and R1 = 5.82 ± 0.03 R⊙ for the primary and M2 = 5.46 ± 0.09 M⊙ and R2 = 3.14 ± 0.08 R⊙ for the secondary. Based on the position of the two stars plotted on a theoretical H-R diagram, we find that the age of the system is ?28 Myr, according to stellar evolutionary models. The spectroscopic and photometric results are in agreement with those obtained using theoretical predictions. 相似文献
12.
A. E. Rosenbush 《Astrophysics》1999,42(3):270-274
A review of light curves of known x-ray novae made it possible to identify criteria by which x-ray nova candidates were selected
among old novae: amplitude of optical outburst 7–10
m, shape of light curve during the outburst with a temporary fading by 2–3m lasting up to four days and an abrupt final fading from the 6m level (relative to the quiet state). We identified LS And, AL Com, V592 Her, and HV Vir as x-ray nova candidates. Recurrent
outbursts should be expected for the first and third stars. Less reliable candidates are V341 Nor, V787 Sgr, and V719 Sco.
A possible recurrent nova candidate may be V1330 Cyg.
Translated from Astrofizika, Vol. 42, No. 3, pp. 359–364, July–September, 1999. 相似文献
13.
Coagulation models assume a higher sticking threshold for micrometer-sized ice particles than for micrometer-sized silicate particles. However, in contrast to silicates, laboratory investigations of the collision properties of micrometer-sized ice particles (in particular, of the most abundant H2O-ice) have not been conducted yet. Thus, we used two different experimental methods to produce micrometer-sized H2O-ice particles, i.e. by spraying H2O droplets into liquid nitrogen and by spraying H2O droplets into a cold nitrogen atmosphere. The mean particle radii of the ice particles produced with these experimental methods are (1.49 ± 0.79) μm and (1.45 ± 0.65) μm. Ice aggregates composed of the micrometer-sized ice particles are highly porous (volume filling factor: ? = 0.11 ± 0.01) or rather compact (volume filling factor: ? = 0.72 ± 0.04), depending on the method of production. Furthermore, the critical rolling friction force of FRoll,ice = (114.8 ± 23.8) × 10−10 N was measured for micrometer-sized ice particles, which exceeds the critical rolling friction force of micrometer-sized SiO2 particles . This result implies that the adhesive bonding between micrometer-sized ice particles is stronger than the bonding strength between SiO2 particles. An estimation of the specific surface energy of micrometer-sized ice particles, derived from the measured critical rolling friction forces and the surface energy of micrometer-sized SiO2 particles, results in γice = 0.190 J m−2. 相似文献
14.
This paper reports 13CO, C18O, HCO+ (J = 1−0) spectral observations toward IRAS 23133+6050 with the 13.7 m millimeter-wave telescope at Qinghai Station of PMO. Corresponding to the 13CO, C18O, HCO+ line emissions, the size of the observed molecular cloud core is 4.0 pc, 2.1 pc and 2.3 pc, the virial mass is 2.7 × 103 M⊙, 0.9 × 103 M⊙ and 2.3 × 103 M⊙, and the volume density of H2 is 2.7 × 103 cm−3, 5.1 × 103 cm−3 and 4.6 × 103 cm−3, respectively. Using the power-law function n(r) ∼r−p, the spatial density distribution of the cloud core was analyzed, the obtained exponent p is respectively 1.75, 1.56 and 1.48 for the 13CO, C18O and HCO+ cores, and it is found that the density distribution becomes gradually flatter from the outer region to the inner region of the core. The HCO+ abundance is 4.6 × 10−10, one order of magnitude less than the value for dark clouds, and slightly less than that for giant molecular clouds. The 13CO/C18O relative abundance ratio is 12.2, comparable with the value 11.8 for dark clouds, and the value 9.0 ∼ 15.6 for giant molecular clouds. A 13CO bipolar outflow is found in this region. The IRAS far-infrared luminosity and the virial masses give the luminosity-mass ratios 18.1, 51.1 and 21.2 from the three lines. 相似文献
15.
D. Jacquemart E. Lellouch C. de Bergh N. Lacome M. Tomasko 《Planetary and Space Science》2008,56(5):613-623
Laboratory spectra of methane-nitrogen mixtures have been recorded in the near-infrared range (1.0-1.65 μm) in conditions similar to Titan's near surface, to facilitate the interpretation of the DISR/DLIS (DISR—Descent Imager/Spectral Radiometer) spectra taken during the last phase of the descent of the Huygens Probe, when the surface was illuminated by a surface-science lamp. We used a 0.03 cm−1 spectral resolution, adequate to resolve the lines at high pressure (pN2∼1.5 bar). By comparing the laboratory spectra with synthetic calculations in the well-studied ν2+2ν3 band (7515-7620 cm−1), we determine a methane absorption column density of 178±20 cm atm and a temperature of 118±10 K in our experiment. From this, we derive the methane absorption coefficients over 1.0-1.65 μm with a 0.03 cm−1 sampling, allowing for the extrapolation of the results to any other methane column density under the relevant pressure and temperature conditions. We then revisit the calibration and analysis of the Titan “lamp-on” DLIS spectra. We infer a 5.1±0.8% methane-mixing ratio in the first 25 m of Titan's atmosphere. The CH4 mixing ratio measured 90 s after landing from a distance of 45 cm is found to be 0.92±0.25 times this value, thus showing no post-landing outgassing of methane in excess of ∼20%. Finally, we determine the surface reflectivity as seen between 25 m and 45 cm and find that the 1500 nm absorption band is deeper in the post-landing spectrum as compared to pre-landing. 相似文献
16.
W. Liller 《Astrophysics and Space Science》1987,131(1-2):449-452
Recent statistics indicate that each year an average of 3.5 novae or nova-like objects are discovered in the Galaxy. With reasonable assumptions about the completeness of the surveys, we arrive at an overall galactic production rate of 76±38 y–1. When recurrent novae are omitted, this rate drops to 60±30 y–1. Hence, it seems that our Galaxy is more prolific than M31 in nova production. The total amount of material released into galactic space by novae each year is about one-tenth that ejected by supernovae.Paper presented at the IAU Colloquium No. 93 on Cataclysmic Variables. Recent Multi-Frequency Observations and Theoretical Developments, held at Dr. Remeis-Sternwarte Bamberg, F.R.G., 16–19 June, 1986. 相似文献
17.
New laboratory spectra of crystalline and amorphous diacetylene ice have been recorded in the range of 7000-500 cm−1 (1.4-20 μm) to aid in the identification of solid diacetylene on Saturn's moon Titan. We have established that amorphous diacetylene ice is stable only at temperatures less than 70±1 K. With respect to observations on Titan, the best approach would be to utilize future space-based telescopes to search for the ν4 (3277/3271 cm−1) in absorption against the reflected light from the sun and the slightly weaker ν8 absorption bands (676/661 cm−1) in absorption against the continuum emission. 相似文献
18.
In order to obtain the substantial information about the surface physics and thermal property of the target asteroid (162173) 1999 JU3, which will be visited by Hayabusa 2 in a sample return mission, with the Advanced Thermal Physical Model (ATPM) we estimate the possible thermal inertia distribution over its surface, and infer the major material composition of its surface materials. In addition, the effective diameter and geometric albedo are derived to be Deff = 1.13 ± 0.03 km, pv = 0.042 ± 0.003, respectively, and the average thermal inertia is estimated to be about (300 ± 50) J m-2 s-0.5 K-1 According to the derived thermal inertia distribution, we infer that the major area on the surface of the target asteroid may be covered by loose materials, such as rock debris, sands, and so on, but few bare rocks may exist in a very small region. In this sense, the sample return mission of Hayabusa 2 is feasible, when it is performed successfully, it will certainly bring significant scientific information to the research of asteroids. 相似文献
19.
Thomas K. Greathouse Matthew Richter Julianne Moses Therese Encrenaz Dan Jaffe 《Icarus》2011,214(2):606-621
Using TEXES, the Texas Echelon cross Echelle Spectrograph, mounted on the Gemini North 8-m telescope we have mapped the spatial variation of H2, CH4, C2H2 and C2H6 thermal-infrared emission of Neptune. These high-spectral-resolution, spatially resolved, thermal-infrared observations of Neptune offer a unique glimpse into the state of Neptune’s stratosphere in October 2007, LS = 275.4° just past Neptune’s southern summer solstice (LS = 270°). We use observations of the S(1) pure rotational line of molecular hydrogen and a portion of the ν4 band of methane to retrieve detailed information on Neptune’s stratospheric vertical and meridional thermal structure. We find global-average temperatures of 163.8 ± 0.8, 155.0 ± 0.9, and 123.8 ± 0.8 K at the 7.0 × 10−3-, 0.12-, and 2.1-mbar levels with no meridional variations within the errors. We then use the inferred temperatures to model the emission of C2H2 and C2H6 in order to derive stratospheric volume mixing ratios (hence forth, VMR) as a function of pressure and latitude. There is a subtle meridional variation of the C2H2 VMR at the 0.5-mbar level with the peak abundance found at −28° latitude, falling off to the north and south. However, the observations are consistent within error to a meridionally constant C2H2 VMR of at 0.5 mbar. We find that the VMR of C2H6 at 1-mbar peaks at the equator and falls by a factor of 1.6 at −70° latitude. However, a meridionally constant VMR of at the 1-mbar level for C2H6 is also statistically consistent with the retrievals. Temperature predictions from a radiative-seasonal climate model of Neptune that assumes the hydrocarbon abundances inferred in this paper are lower than the measured temperatures by 40 K at 7 × 10−3 mbar, 30 K at 0.12 mbar and 25 K at 2.1 mbar. The radiative-seasonal model also predicts meridional temperature variations on the order of 10 K from equator to pole, which are not observed. Assuming higher stratospheric CH4 abundance at the equator relative to the south pole would bring the meridional trends of the inferred temperatures and radiative-seasonal model into closer agreement.We have also retrieved observations of C2H4 emission from Neptune’s stratosphere using TEXES on the NASA Infrared Telescope Facility (IRTF) in June 2003, LS = 266°. Using the observations from the middle of the planet and an average of the middle three latitude temperature profiles from the 2007 observations (9.5° of LS later, the seasonal equivalent of 9.5 Earth days within Earth’s seasonal cycle), we infer a C2H4 VMR of at 1.5 × 10−3 mbar, a value that is 3.25 times that predicted by global-average photochemical models. 相似文献
20.
We present a statistical analysis of the big blue bump (BBB) feature for a large heterogeneous sample of 95 optically selected and soft X-ray bright, low redshift active galactic nuclei (AGNs). This sample covers a sufficiently broad luminosity range, allowing us to test the luminosity dependence of the spectral energy distribution in the BBB region. Following the works of Zheng et al., Laor et al. and Kriss et al., we introduce the broad band spectral index from 1050 Å to0.5 keV (α UV-SX ), compare its distribution with that of the soft X-ray spectral index (α SX ) obtained by ROSAT PSPC, and find that the two indices have equal average-values within 1 ～ 2σuncertainties, whether in the whole sample, in luminosity divisions or in subsamples. These equalities also have no obvious luminosity dependence. This indicates that a single power law can describe the overall UV toX-ray spectrum in a statistical sense, or the broad band UV to soft X-ray spectrum is the soft X-ray spectral extension on an average. Thus, our results support Laor et al.'s conjecture about the BBB peak aroundFUV 1050 Å from a statistical viewpoint. As we further test whether the equality holds for individual objects within measure errors, χ2 test refuse to accept it. In addition, our statistical results, from the luminosity divisions and on the correlation of spectral indices with luminosity (M B), imply that the luminosity dependence of α UV and α UV-SX is mainly due to absorption in low luminosity AGNs. 相似文献