Sizes of active galaxies

The diameters of active galaxies were compared with the diameters of ordinary galaxies. It is shown that, within the same luminosity limits, they do not differ clearly from each other. Starlike active galaxies in the samples of active galaxies have any possible luminosities. The parent galaxies of quasars have different diameters and, in accordance with their sizes, can be either elliptical or spiral. Translated from Astrofizika, Vol. 43, No. 2, pp. 191-196, April–June, 2000.     

The Relative Sizes of Planetary Nebulae

The sizes of planetary nebulae are poorly known, principally because the distances to these sources are not very well established. We point out in the following, however, that if one is careful in selecting nebulae having particular ranges of galactic latitude, and narrow ranges of surface brightness, then it should be possible to establish mean trends in nebular diameter. We have, in this way, been able to determine that where brightness temperatures are the same, then circular and elliptical sources, and the nuclei of bipolar nebulae (BPNe) all have closely similar mean dimensions. It is also likely that circular and elliptical sources have closely similar masses (the case of the BPNe is less clear). Finally, we note that halos are typically ∼3 times larger than circular and elliptical PNe, and the lobes of BPNe are ∼5 times as large, making the latter envelopes the largest of all nebular structures. This revised version was published online in July 2006 with corrections to the Cover Date.     

Counts, Sizes and Colours of Faint Infrared-Selected Galaxies

Deep J- and K _s-band images covering a 5 × 5 arcmin area centred on the NTT Deep Field have been obtained during the Science Verification of SOFI at the NTT. These images were made available via the Web in early June, 1998. The preliminary results we have obtained by the analysis of these data are the following: (i) the counts continue to rise with no evidence of a turnover or of a flattening down to the limits of the survey (K _s = 22.5 and J = 24 mag); (ii) we find a slope d log(N)/dm≈ 0.37, in agreement with most of the faintest surveys but much steeper than the Hawaii survey; (iii) fainter than K _s ≈ 19and J ≈ 20 mag, the median J-K colour of galaxies shows a break in its reddening trend turning toward bluer colours; (iv) faint bluer galaxies also display a larger compactness index, and a smaller apparent size. This revised version was published online in July 2006 with corrections to the Cover Date.     

活动星系致密核视角大小的统计研究

本文对ＶＬＢＩ观测得到的河外射电源致密核ｃｏｒｅ的视角大小进行了统计研究，发现对单个源平均上视角大小近似反比于观测频率，与目前的模型相一致。在５ＧＨｚ上，在红移范围０．０４＜ｚ＜２．５内，平均的ｃｏｒｅ视角大小近似为常数，在非均匀喷流模型框架下，一种可能的解释是在河外射电源致密结构中磁场存在着演化。     

行星际磁通量绳尺度及能量研究

行星际磁通量绳是太阳风中一种重要的磁结构.从1995-2001年的Wind卫星的观测资料中认证了144个行星际磁通量绳.其时间尺度介于几十分钟到几十小时之间,其空间尺度呈现连续分布.通过估算磁通量绳单位长度的能量和总能量发现:磁通量绳的能量分布和耀斑的类似都呈现很好的幂率谱.通过讨论行星际磁通量绳和太阳活动爆发的关系,建议所有的小、中、大尺度通量绳都直接起源于太阳上的爆发,和磁云对应于通常的日冕物质抛射一样,中、小尺度的通量绳对应相对较小的日冕物质抛射.     

Sizes, shapes, and albedos of the inner satellites of Neptune

Based on 87 resolved Voyager images of the five innermost satellites of Neptune, their shapes were measured and fit by tri-axial ellipsoids with the semi-axes of 48 × 30 × 26 km for Naiad, 54 × 50 × 26 km for Thalassa, 90 × 74 × 64 km for Despina, 102 × 92 × 72 km for Galatea, and 108 × 102 × 84 km for Larissa. Thomas and Veverka published a similar shape for Larissa (104 × 89 km, J. Geophys. Res. 96, 19261-19268, 1991). The other satellites had no published shapes. Using Voyager photometry of the six inner satellites by the same authors and the revised sizes, including the published size of Proteus, the reflectivity within this inner system was found to vary by about 30%. Geometric albedos in the visible are estimated between 0.07 for Naiad and 0.10 for Proteus. The rotational lightcurves of these satellites seem to be due to satellite shapes.     

The Characteristic Sizes of the Sunspots and Pores in Solar Cycle 24

Recent dedicated Hinode polar region campaigns revealed the presence of concentrated kilogauss patches of the magnetic field in the polar regions of the Sun, which are also shown to be correlated with facular bright points at the photospheric level. In this work, we demonstrate that this spatial intermittency of the magnetic field persists even up to the chromospheric heights. The small-scale bright elements visible in the bright network lanes of the solar network structure as seen in the Ca ii H images are termed network bright points. We use special Hinode campaigns devoted to the observation of polar regions of the Sun to study the polar network bright points during the phase of the last extended solar minimum. We use Ca ii H images of chromosphere observed by the Solar Optical Telescope. For magnetic field information, level-2 data of the spectro-polarimeter is used. We observe a considerable association between the polar network bright points and magnetic field concentrations. The intensity of such bright points is found to be correlated well with the photospheric magnetic field strength underneath with a linear relation existing between them.

     

The Dependence of Chromospheric Ca II K Network Cell Sizes on Solar Latitude

Calcium K line spectroheliograms obtained during the solar minimum phases at Kodaikanal between 1913–1974 have been used to study the network cell sizes. The autocorrelation is calculated for two-dimensional strips at 5° interval up to ±50° latitude. The average size of the network cells was found to have a dependence on solar latitude with a maximum variation of about 7%. The pattern shows an apparent north–south symmetry with two minima at about 20° N and S.     

Saturn's F Ring: Kinematics and Particle Sizes from Stellar Occultation Studies

The occultation of GSC5249-01240 by Saturn's rings was observed in a spectrally resolved mode using the Faint Object Spectrograph on the Hubble Space Telescope. By combining these data with other occultation data, we have determined the inclination of the F ring to be 0.0065±0.0014 deg. Our inclined F ring orbit model explains an abrupt decrease in flux at the west ansa of the ring that was observed during the November 1995 ring-plane crossing as well as the nondetection of 1995 S5 during one set of observations in November 1995. The F ring's equivalent depth is found to have no significant dependence on wavelength between 0.27 and 0.74 μm, indicating the presence of a population of ring particles larger in size than ∼10 μm. This contrasts with the results from a previous analysis of Voyager images at various phase angles, in which the particles were determined to be predominantly submicron in size. The difference may be due to temporal or longitudinal variability within the ring.     

Sizes of the stellar subsystems of galaxies and intracluster stars in the Virgo cluster

Stellar photometry for three fields in the Virgo cluster of galaxies has been performed on the basis of archival Hubble Space Telescope ACS/WFC images. The densely populated red giant branches belonging to cluster galaxies are seen on the constructed Hertzsprung–Russell diagrams. The distances to eight galaxies in the Virgo cluster have been determined by the TRGB method. The sizes of the stellar subsystems and the gradients in the number density of red giants along the galactic radius have been determined for the investigated galaxies. The stellar periphery of the galaxies has been found to extend to great distances and to cover the entire area of the images used. Therefore, the stars that have previously been thought to be intracluster stars actually belong to the periphery of neighboring galaxies.     

Mony a Mickle Maks a Muckle: Minor Body Observations with Optical Telescopes of All Sizes

I review the current capabilities of small, medium and large telescopes in the study of minor bodies of the Solar System (MBOSS), with the goal of identifying those areas where the next generation of Extremely Large Telescopes (ELTs) are required to progress. This also leads to a discussion of the synergies between large and small telescopes. It is clear that the new facilities that will become available in the next decades will allow us to discover smaller and more distant objects (completing size distributions) and to characterise and even resolve larger individual bodies and multiple systems, however we must also recognise that there is still much to be learned from wide surveys that require more time on more telescopes than can ever be available on ELTs. Smaller telescopes are still required to discover and characterise large samples of MBOSS.     

Sizes, shapes, and derived properties of the saturnian satellites after the Cassini nominal mission

The Cassini spacecraft has provided data on over twenty satellites orbiting Saturn. In this study we update the shape measurements derived from imaging data of nearly all the observed regular satellites (those with low eccentricities and inclinations) and briefly discuss some of the implications of their properties. In particular, the improved data show that Rhea’s shape is hydrostatic.     

Reflection of acoustic waves in the real solar atmosphere

We use space-time variations of velocity restored from observations to isolate acoustic waves propagating into upper layers of the atmosphere. At reflection, acoustic ten-minute waves penetrate into the evanescent layers of the photosphere up to the temperature-minimum layers, and five-minute waves reach the layers of the lower chromosphere.     

Asteroid hazard,real problems and practical actions

The paper refers to the current status of asteroid hazard in Russia and abroad. The authors emphasize the relevance of a sober assessment of its real state and specific circumstances working from the principle of reasonable sufficiency. The paper presents a practical approach to the asteroid hazard problem. It consists of a proposal for a mission to the Apophis asteroid and to define the main parameters of this hazardous celestial body. The article also considers how the spacecraft would look, as well as its mission profile for the period of 2012–2014.     

A comparison of artificial solar granules with real solar granules

The lifetimes, characteristics of the shapes as well as lengths and perimeters of artificial solar granules (Nordlund, 1982, 1984a) are compared with data from the literature and parameters determined from two different sets of observed granules. No significant differences of the parameters for these sets of granules are detectable.Mitteilungen aus dem Kiepenheuer-Institut Nr. 251.     

A new iterative technique for the deconvolution of real data

A fast new deconvolution technique has been developed which employs a complex iterative scheme in order to deconvolve severely broadened noisy data. A great many computer-simulated experiments have been made using the iterative scheme in order to test its reliability and stability in many different situations. It is found to be extremely reliable in the reclaiming of partially resolved multi-featured spectra and can be used with any type of instrumental profile. Deconvolution of single Gaussian features are achieved in 5% noise conditions, where the instrumental profile is 5 times broader than the spectral features to be reclaimed.