共查询到20条相似文献，搜索用时 212 毫秒
1.
O'Donoghue Koen Lynas-Gray Kilkenny & van Wyk 《Monthly notices of the Royal Astronomical Society》1998,296(2):306-316
We report the discovery of rapid oscillations in the sdB star PG 1047+003. The oscillations are multiperiodic, with nine periods in the range 104–162 s. The optical spectrum of PG 1047+003 is consistent with that of a single sdB star. Line profile fitting yields an effective temperature of 35 000±1000 K and log g =5.9±0.1, although optical photometry and IUE spectrophotometry may indicate a cooler effective temperature. These properties demonstrate that PG 1047+003 is an EC 14026 star, a recently discovered class of sdB pulsators. Optical and infrared photometry constrains any cool companion to the sdB star to be a main-sequence star of spectral type M0 or later. With V =13.47 and a relatively rich pulsation spectrum, PG 1047+003 is an attractive target for an intensive photometric campaign to extract more periods from the light curve which, along with a suitable grid of pulsation models, will probe the interior structure of the star. 相似文献
2.
3.
D. J. Wilman † M. L. Balogh ‡ R. G. Bower J. S. Mulchaey A. Oemler Jr R. G. Carlberg S. L. Morris R. J. Whitaker 《Monthly notices of the Royal Astronomical Society》2005,358(1):71-87
The evolution of galaxies in groups may have important implications for the evolution of the star formation history of the Universe, since many processes which operate in groups may suppress star formation and the fraction of galaxies in bound groups grows rapidly between z = 1 and the present day. In this paper, we present an investigation of the properties of galaxies in galaxy groups at intermediate redshift ( z ∼ 0.4) . The groups were selected from the Canadian Network for Observational Cosmology Redshift Survey (CNOC2) redshift survey as described by Carlberg et al., with further spectroscopic follow-up undertaken at the Magellan telescope in order to improve the completeness and depth of the sample. We present the data for the individual groups, and find no clear trend in the fraction of passive galaxies with group velocity dispersion and group concentration. We stack the galaxy groups in order to compare the properties of group galaxies with those of field galaxies at the same redshift. The groups contain a larger fraction of passive galaxies than the field, this trend being particularly clear for galaxies brighter than M B J < −20 in the higher velocity dispersion groups. In addition, we see evidence for an excess of bright passive galaxies in the groups relative to the field. In contrast, the luminosity functions of the star-forming galaxies in the groups and the field are consistent. These trends are qualitatively consistent with the differences between group and field galaxies seen in the local Universe. 相似文献
4.
D. J. Wilman † M. L. Balogh ‡ R. G. Bower J. S. Mulchaey A. Oemler Jr R. G. Carlberg V. R. Eke I. Lewis S. L. Morris R. J. Whitaker 《Monthly notices of the Royal Astronomical Society》2005,358(1):88-100
We compare deep Magellan spectroscopy of 26 groups at 0.3 ≤ z ≤ 0.55 , selected from the Canadian Network for Observational Cosmology 2 field survey, with a large sample of nearby groups from the 2PIGG catalogue. We find that the fraction of group galaxies with significant [O ii ]λ3727 emission (≥5 Å) increases strongly with redshift, from ∼29 per cent in 2dFGRS to ∼58 per cent in CNOC2, for all galaxies brighter than ∼ M * + 1.75 . This trend is parallel to the evolution of field galaxies, where the equivalent fraction of emission-line galaxies increases from ∼53 to ∼75 per cent. The fraction of emission-line galaxies in groups is lower than in the field, across the full redshift range, indicating that the history of star formation in groups is influenced by their environment. We show that the evolution required to explain the data is inconsistent with a quiescent model of galaxy evolution; instead, discrete events in which galaxies cease forming stars (truncation events) are required. We constrain the probability of truncation ( P trunc ) and find that a high value is required in a simple evolutionary scenario neglecting galaxy mergers ( P trunc ≳ 0.3 Gyr−1 ) . However, without assuming significant density evolution, P trunc is not required to be larger in groups than in the field, suggesting that the environmental dependence of star formation was embedded at redshifts z ≳ 0.45 . 相似文献
5.
35 Seasons of U.S. Antarctic Meteorites: A Pictorial Guide to the Collection,edited by K. Righter,C. M. Corrigan,T. J. McCoy and R. P. Harvey. Hoboken,New Jersey: Wiley, 2014, 320 p. $99.95, hardcover (ISBN #978‐1‐118‐79832‐4).
下载免费PDF全文
下载免费PDF全文 Nicolle E. B. Zellner 《Meteoritics & planetary science》2015,50(12):2140-2141
6.
7.
8.
9.
10.
Roman Skla 《Meteoritics & planetary science》2001,36(7):1007-1007
11.
12.
13.
C.Desmond Walshaw 《Planetary and Space Science》1989,37(12):1485-1507
14.
15.
Itziar Aretxaga David H. Hughes Kristen Coppin Angela M. J. Mortier Jeff Wagg James S. Dunlop Edward L. Chapin Stephen A. Eales Enrique Gaztañaga Mark Halpern Rob J. Ivison Eelco van Kampen Douglas Scott Stephen Serjeant Ian Smail Thomas Babbedge rew J. Benson Scott Chapman David L. Clements Loretta Dunne Simon Dye Duncan Farrah Matt J. Jarvis Robert G. Mann Alexandra Pope Robert Priddey Steve Rawlings Marc Seigar Laura Silva Chris Simpson Mattia Vaccari 《Monthly notices of the Royal Astronomical Society》2007,379(4):1571-1588
16.
17.
Ralph D. Lorenz 《Meteoritics & planetary science》2014,49(6):1139-1140
18.
19.
20.
Odette B. JAMES Barbara A. COHEN Lawrence A. TAYLOR Mikhail A. NAZAROV 《Meteoritics & planetary science》2007,42(6):1029-1032
Abstract We described lunar meteorite Dhofar 026 (Cohen et al. 2004) and interpreted this rock as a strongly shocked granulitic breccia (or fragmental breccia consisting almost entirely of granulitic‐breccia clasts) that was partially melted by post‐shock heating. Warren et al. (2005) objected to many aspects of our interpretation: they were uncertain whether or not the bulk rock had been shocked; they disputed our identification of the precursor as granulitic breccia; and they suggested that mafic, igneous‐textured globules within the breccia, which we proposed were melted by post‐shock heating, are clasts with relict textures. The major evidence for shock of the bulk rock is the fact that the plagioclase in the lithologic domains that make up 80–90% of the rock is devitrified maskelynite. The major evidence for a granulitic‐breccia precursor is the texture of the olivine‐plagioclase domain that constitutes 40—45% of the rock; Warren et al. apparently overlooked or ignored this lithology. Textures of the mafic, igneous‐textured globules, and especially of the vesicles they contain, demonstrate that these bodies were melted and crystallized in situ. Warren et al. suggested that the rock might have originally been a regolith breccia, but the textural homogeneity of the rock and the absence of solar wind—derived noble gases preclude a regolith‐breccia precursor. Warren et al. classified the rock as an impact‐melt breccia, but they did not identify any fraction that was impact melt. 相似文献