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1.
We have investigated the correlations among color, morphology and luminosity for all LRGs, cut I LRGs, cut II LRGs, and Main
galaxies that are also classified as LRGs. It is found that the morphology of LRGs is tightly correlated with luminosity.
The rest-frame u-g color of cut I LRGs and cut II LRGs is nearly independent of luminosity, but the color of Main galaxies
is correlated with luminosity. For cut I LRGs and Main galaxies, the early type proportion apparently changes with color:
at the rest-frame u-g < 1.3 it increases strongly with increasing color, while at the rest-frame u-g > 1.3 it decreases with
increasing color. We also notice that the morphology of cut II LRGs is only a weak function of color.
Published in Astrofizika, Vol. 50, No. 3, pp. 335–345 (August 2007). 相似文献
2.
Xin-Fa Deng Ji-Zhou He Jian-Ying Xu Ying-Ping Ding 《Astrophysics and Space Science》2009,323(3):273-279
From the approximately volume-limited Luminous Red Galaxy (LRG) sample of the Sloan Digital Sky Survey Data Release 6 (SDSS
DR6), we construct three LRG samples with different g-r color, which have the nearly same number density, to investigate the
color dependence of clustering properties of LRGs. It is found that the blue galaxies have a more filamentary distribution
than red galaxies, and that the bluest LRGs preferentially inhabit the dense groups and clusters. But in three LRG samples
with different u-g color, we do not observe the tendency for clustering properties of LRGs to significantly change with color.
We preferentially conclude that the clustering properties of LRGs are not strongly correlated with colors. 相似文献
3.
4.
In order to compare color statistical properties of member galaxies in compact groups with those of field galaxies, we use
a compact group (CG) sample which contains 4217 CGs extracted from the MAIN galaxy sample of the SDSS Data Release 4 (SDSS4),
and construct a random group sample which has the same distributions of redshift and number of member galaxies as those of
the CG sample. It turns out that the mean colors of galaxies in CGs are redder than those of galaxies in random groups. Additionally,
we also find that member galaxies in real CGs have a smaller dispersion of colors than those in random groups-at least for
g-r, r-i, and i-z colors.
Published in Astrofizika, Vol. 50, No. 1, pp. 29–37 (February 2007). 相似文献
5.
镁合金作为最轻的金属结构材料,具有比强度高、比刚度高、减震性能好、电磁屏蔽等优点。随着海洋强国战略的实施,先进镁合金结构材料逐步在海洋装备上开始应用。已列装的新型高强AZ80镁合金,通过与QBe1.7铍青铜紧固件连接,共同构成整体在典型海洋大气环境中服役。在高盐、高湿的海洋环境环境中,镁合金与电位更正的QBe1.7铍青铜偶接后,极易发生电偶腐蚀。电位相对更负的高强AZ80镁合金,作为电偶腐蚀的阳极被加速溶解。本研究对高强AZ80镁合金电偶腐蚀样品经过12个月青岛海洋大气暴露试验,发现空白对照组、电偶1组(紧固件铍青铜直径Ψ=10mm)和电偶2组(紧固件铍青铜直径Ψ=20mm)的平均腐蚀速率分别为108.1071、133.8929、173.6250g/(m~2·a)。电偶对表面的主要腐蚀产物为:Mg(OH)_2、MgSO_4和MgCl_2。空白样品、电偶1组和电偶2组平均腐蚀深度分别为:0.175、0.330、0.315mm/a。样品中部腐蚀深度最大,边部腐蚀深度则相对较小。不同样品在青岛试验站的腐蚀产物对基体保护能力的量度(n值)分别为1.1337、1.1378、1.0895,表明随着暴露时间的延长,试样在海洋大气环境中的腐蚀速率会加快,试样表面的腐蚀产物对基体根本起不到保护作用。通过灰色关联分析法,计算了青岛海洋大气腐蚀站点的环境因素与AZ80镁合金腐蚀深度和腐蚀失重之间的关联度,结果表明:青岛海洋大气环境因素对高强AZ80镁合金空白样品腐蚀失重影响前三位分别为:SO_4~(2-)非水溶性硫酸盐转化率;对电偶1组样品影响前三位的环境因素分别为:SO_2硫酸盐转化率NO_2;对电偶2组样品影响前三位的环境因素分别为:水溶性降尘SO_2NH_3。对比电偶对2组和1组,唯一的差别是电偶对的面积比,但决定镁合金腐蚀速度的大气成分完全不同,相关机制会在未来工作中详细研究。 相似文献
6.
本文以热浸锌处理的CM系列钢为研究对象,通过盐雾处理进行了加速腐蚀试验,利用电化学极化测试分析了材料的腐蚀机理,利用扫描电镜和三维数字显微镜观察了材料的表面形貌。盐雾加速试验表明,随着时间增长腐蚀速度降低,主要是由于腐蚀产物膜抑制了腐蚀的阳极过程和阴极过程（产生钝化平台）。厌氧环境下的试验表明,在细菌繁殖到达高峰时产生了钝化平台,主要是形成致密、溶解度极小的ZnS腐蚀产物,在电极表面形成连续完整的腐蚀产物膜。以99.99%纯锌为原料的热浸锌产品在港湾海洋环境中有高的耐蚀性,其原因是由于腐蚀产物及锌-铁合金层的保护作用。 相似文献
7.
Xin-Fa Deng Yi-Qing Chen Ping Wu Cheng-Hong Luo Ji-Zhou He Mathematics Physics College Nanchang University Nanchang Management College Nanchang University Nanchang 《中国天文和天体物理学报》2006,6(4):411-420
From the Main galaxy data of the SDSS Data Release 4 (SDSS4), we have identified close galaxy pairs at neighbourhood radius R = 100 kpc by three-dimensional cluster analysis. Using the criterion that an "isolated galaxy pair" must be separated from its "nearest neighbor" by more than 500 kpc, we constructed an isolated galaxy pair sample of 1158 pairs. We also constructed a random pair sample by randomly selecting 1158 galaxy pairs from the Main galaxy sample, which has the same redshift distribution as the isolated galaxy pair sample, and in which the two components of any pair have the same redshifts. Comparative studies of luminosity and size between the members of the galaxy pairs are performed. We find and further confirm there is no tendency for paired galaxies to have similar luminosities or sizes. From the isolated pair sample we also selected a subsample with the magnitude limit of the primary raised by 2 magnitudes, so as to include pairs in which the secondary is 2 magnitudes fainter than the primary. This subsample contains 82 pairs. A random pair sample is similarly constructed. 相似文献
8.
Xin-Fa Deng~ Yi-Qing Chen~ Qun Zhang~ Ji-Zhou He~ Mathematics Physics College Nanchang University Jiangxi Management College Nanchang University Nanchang 《中国天文和天体物理学报》2006,6(1):35-42
We study the super-large-scale structures in the Sloan Digital Sky Survey by cluster analysis,and examine the geometry and the properties of the member galaxies.Two subsamples are selected from the SDSS,Subsample 1 at the celestial equator and Subsample 2 further north.In Subsample 1 we discover two compact super-large-scale structures:the Sloan Great Wall and the CfA Great Wall.The Sloan Great Wall,located at a median redshift of z=0.07804,has a total length of about 433 Mpc and a mean galaxy density of about six times that of the whole sample. Most of its member galaxies are of medium size and brightness.The CfA Great Wall, located at a median redshift of z=0.03058,has a total length of about 251 Mpc and includes large percentages of faint and small galaxies and relatively fewer early-type galaxies. 相似文献
9.
Using a volume-limited sample of Main Galaxies from SDSS Data Release 5,we investigate the dependence of galaxy properties on local environment.For each galaxy,a local three-dimensional density is calculated.We find that the galaxy morphological type depends strongly on the local environment:galaxies in dense environments have predominantly early type morphologies.Galaxy colors have only a weak dependence on the environment.This puts an important constraint on the process of galaxy formation. 相似文献
10.
Using the Luminous Red Galaxy (LRG) sample of the SDSS Data Release 6, we investigate the dependence of LRG properties on
the local environment. For each LRG, the local three-dimensional density within the distance to the 5th nearest galaxy is
calculated. It turns out that there is no strong local environmental dependence of LRG morphologies, and that other galaxy
properties do not present significant dependence on the local environment. We further calculate the local three-dimensional
galaxy density within the distance to the 10th nearest galaxy, and find that results are similar to those for local density
within the distance to the 5th nearest galaxy.
Published in Astrofizika, Vol. 51, No. 2, pp. 189–200 (May 2008). 相似文献