ALBERT

Description: We present a new deep determination of the spectroscopic luminosity function (LF) within the virial radius of the nearby and massive Abell 85 (A85) cluster down to the dwarf regime ( M * + 6) using Very Large Telescope/Visible Multi-Object Spectrograph (VLT/VIMOS) spectra for ~2000 galaxies with m r ≤ 21 mag and 〈μ e , r 〉 ≤ 24 mag arcsec –2 . The resulting LF from 438 cluster members is best modelled by a double Schechter function due to the presence of a statistically significant upturn at the faint end. The amplitude of this upturn ( $\alpha _{{\rm f}} = -1.58^{+0.19}_{-0.15}$ ), however, is much smaller than that of the Sloan Digital Sky Survey (SDSS) composite photometric cluster LF by Popesso et al., α f ~ –2. The faint-end slope of the LF in A85 is consistent, within the uncertainties, with that of the field. The red galaxy population dominates the LF at low luminosities, and is the main factor responsible for the upturn. The fact that the slopes of the spectroscopic LFs in the field and in a cluster as massive as A85 are similar suggests that the cluster environment does not play a major role in determining the abundance of low-mass galaxies.

Description: Of the 342 planets so far discovered orbiting other stars, 58 'transit' the stellar disk, meaning that they can be detected through a periodic decrease in the flux of starlight. The light from the star passes through the atmosphere of the planet, and in a few cases the basic atmospheric composition of the planet can be estimated. As we get closer to finding analogues of Earth, an important consideration for the characterization of extrasolar planetary atmospheres is what the transmission spectrum of our planet looks like. Here we report the optical and near-infrared transmission spectrum of the Earth, obtained during a lunar eclipse. Some biologically relevant atmospheric features that are weak in the reflection spectrum (such as ozone, molecular oxygen, water, carbon dioxide and methane) are much stronger in the transmission spectrum, and indeed stronger than predicted by modelling. We also find the 'fingerprints' of the Earth's ionosphere and of the major atmospheric constituent, molecular nitrogen (N(2)), which are missing in the reflection spectrum.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Palle, Enric -- Osorio, Maria Rosa Zapatero -- Barrena, Rafael -- Montanes-Rodriguez, Pilar -- Martin, Eduardo L -- England -- Nature. 2009 Jun 11;459(7248):814-6. doi: 10.1038/nature08050.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Instituto de Astrofisica de Canarias, Via Lactea s/n, E38205 La Laguna, Tenerife, Spain. epalle@iac.es〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19516335" target="_blank"〉PubMed〈/a〉

Description: On 4 July 2005, many observatories around the world and in space observed the collision of Deep Impact with comet 9P/Tempel 1 or its aftermath. This was an unprecedented coordinated observational campaign. These data show that (i) there was new material after impact that was compositionally different from that seen before impact; (ii) the ratio of dust mass to gas mass in the ejecta was much larger than before impact; (iii) the new activity did not last more than a few days, and by 9 July the comet's behavior was indistinguishable from its pre-impact behavior; and (iv) there were interesting transient phenomena that may be correlated with cratering physics.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Meech, K J -- Ageorges, N -- A'Hearn, M F -- Arpigny, C -- Ates, A -- Aycock, J -- Bagnulo, S -- Bailey, J -- Barber, R -- Barrera, L -- Barrena, R -- Bauer, J M -- Belton, M J S -- Bensch, F -- Bhattacharya, B -- Biver, N -- Blake, G -- Bockelee-Morvan, D -- Boehnhardt, H -- Bonev, B P -- Bonev, T -- Buie, M W -- Burton, M G -- Butner, H M -- Cabanac, R -- Campbell, R -- Campins, H -- Capria, M T -- Carroll, T -- Chaffee, F -- Charnley, S B -- Cleis, R -- Coates, A -- Cochran, A -- Colom, P -- Conrad, A -- Coulson, I M -- Crovisier, J -- deBuizer, J -- Dekany, R -- de Leon, J -- Dello Russo, N -- Delsanti, A -- DiSanti, M -- Drummond, J -- Dundon, L -- Etzel, P B -- Farnham, T L -- Feldman, P -- Fernandez, Y R -- Filipovic, M D -- Fisher, S -- Fitzsimmons, A -- Fong, D -- Fugate, R -- Fujiwara, H -- Fujiyoshi, T -- Furusho, R -- Fuse, T -- Gibb, E -- Groussin, O -- Gulkis, S -- Gurwell, M -- Hadamcik, E -- Hainaut, O -- Harker, D -- Harrington, D -- Harwit, M -- Hasegawa, S -- Hergenrother, C W -- Hirst, P -- Hodapp, K -- Honda, M -- Howell, E S -- Hutsemekers, D -- Iono, D -- Ip, W-H -- Jackson, W -- Jehin, E -- Jiang, Z J -- Jones, G H -- Jones, P A -- Kadono, T -- Kamath, U W -- Kaufl, H U -- Kasuga, T -- Kawakita, H -- Kelley, M S -- Kerber, F -- Kidger, M -- Kinoshita, D -- Knight, M -- Lara, L -- Larson, S M -- Lederer, S -- Lee, C-F -- Levasseur-Regourd, A C -- Li, J Y -- Li, Q-S -- Licandro, J -- Lin, Z-Y -- Lisse, C M -- LoCurto, G -- Lovell, A J -- Lowry, S C -- Lyke, J -- Lynch, D -- Ma, J -- Magee-Sauer, K -- Maheswar, G -- Manfroid, J -- Marco, O -- Martin, P -- Melnick, G -- Miller, S -- Miyata, T -- Moriarty-Schieven, G H -- Moskovitz, N -- Mueller, B E A -- Mumma, M J -- Muneer, S -- Neufeld, D A -- Ootsubo, T -- Osip, D -- Pandea, S K -- Pantin, E -- Paterno-Mahler, R -- Patten, B -- Penprase, B E -- Peck, A -- Petitas, G -- Pinilla-Alonso, N -- Pittichova, J -- Pompei, E -- Prabhu, T P -- Qi, C -- Rao, R -- Rauer, H -- Reitsema, H -- Rodgers, S D -- Rodriguez, P -- Ruane, R -- Ruch, G -- Rujopakarn, W -- Sahu, D K -- Sako, S -- Sakon, I -- Samarasinha, N -- Sarkissian, J M -- Saviane, I -- Schirmer, M -- Schultz, P -- Schulz, R -- Seitzer, P -- Sekiguchi, T -- Selman, F -- Serra-Ricart, M -- Sharp, R -- Snell, R L -- Snodgrass, C -- Stallard, T -- Stecklein, G -- Sterken, C -- Stuwe, J A -- Sugita, S -- Sumner, M -- Suntzeff, N -- Swaters, R -- Takakuwa, S -- Takato, N -- Thomas-Osip, J -- Thompson, E -- Tokunaga, A T -- Tozzi, G P -- Tran, H -- Troy, M -- Trujillo, C -- Van Cleve, J -- Vasundhara, R -- Vazquez, R -- Vilas, F -- Villanueva, G -- von Braun, K -- Vora, P -- Wainscoat, R J -- Walsh, K -- Watanabe, J -- Weaver, H A -- Weaver, W -- Weiler, M -- Weissman, P R -- Welsh, W F -- Wilner, D -- Wolk, S -- Womack, M -- Wooden, D -- Woodney, L M -- Woodward, C -- Wu, Z-Y -- Wu, J-H -- Yamashita, T -- Yang, B -- Yang, Y-B -- Yokogawa, S -- Zook, A C -- Zauderer, A -- Zhao, X -- Zhou, X -- Zucconi, J-M -- New York, N.Y. -- Science. 2005 Oct 14;310(5746):265-9. Epub 2005 Sep 8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Institute for Astronomy, University of Hawaii at Manoa, 2680 Woodlawn Drive, Honolulu, HI 96822, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/16150977" target="_blank"〉PubMed〈/a〉

Description: We aim to review the internal structure and dynamics of the Abell 1351 cluster, shown to host a radio halo with a quite irregular shape. Our analysis is based on radial velocity data for 135 galaxies obtained at the Telescopio Nazionale Galileo. We combine galaxy velocities and positions to select 95 cluster galaxy members and analyse the internal dynamics of the whole cluster. We also examine X-ray data retrieved from Chandra and XMM archives. We measure the cluster redshift, 〈 z 〉 = 0.325, the line-of-sight (LOS) velocity dispersion, V  ~ 1500 km s –1 , and the X-ray temperature, kT  ~ 9 keV. From both X-ray and optical data independently, we estimate a large cluster mass, in the 1–4 $\times 10^{15}\;h_{70}^{-1}\;\rm{M}_{{\odot }} \;$ range. We attribute the extremely high value of V to the bimodality in the velocity distribution. We find evidence of a significant velocity gradient and optical 3D substructure. The X-ray analysis also shows many features in favour of a complex cluster structure, probably supporting an ongoing merger of substructures in Abell 1351. The observational scenario agrees with the presence of two main subclusters in the northern region, each with its brightest galaxy (BCG1 and BCG2), detected as the two most important X-ray substructures with a rest-frame LOS velocity difference of V rf  ~ 2500 km s –1 and probably being in large part aligned with the LOS. We conclude that Abell 1351 is a massive merging cluster. The details of the cluster structure allow us to interpret the quite asymmetric radio halo as a ‘normal’ halo plus a southern relic, strongly supporting a previous suggestion based only on inspection of radio and preliminary X-ray data.

Description: We study the dynamical status of the galaxy system ZwCl 2341.1+0000, a filamentary multi-Mpc galaxy structure associated with a complex diffuse radio emission. Our analysis is mainly based on new spectroscopic data for 128 galaxies acquired at the Italian Telescopio Nazionale Galileo. We also use optical data available in the Sloan Digital Sky Survey and X-ray data from the Chandra archive. We select 101 cluster member galaxies and compute the cluster redshift 〈 z 〉 ~ 0.2693 and the global line-of-sight velocity dispersion V ~ 1000 km s –1 . Our optical analysis agrees with the presence of at least three, likely four or more, optical subclusters causing the south-south-east–north-north-west (SSE–NNW) elongation of the galaxy distribution and a significant velocity gradient in the south–north direction. In particular, we detect an important low-velocity subclump in the southern region, roughly coincident with the brightest peak of the diffuse radio emission but with a clear offset between the optical and radio peaks. We also detect one (or two) optical subcluster(s) at north, in correspondence with the second brightest radio emission, and another one in the central cluster region, where a third diffuse radio source has been recently detected. A more refined analysis involving the study of the 2D galaxy distribution suggests an even more complex structure. Depending on the adopted model, we obtain a mass estimate M sys ~ 1–3 $\times \ 10^{15}\;h_{70}^{-1}\;\mathrm{M}_{{\odot }}$ for the whole system. As for the X-ray analysis, we confirm the SSE–NNW elongation of the intracluster medium and detect four significant peaks. The X-ray emission is strongly asymmetric and offsetted with respect to the galaxy distribution, thus suggesting a merger caught in the phase of post-core–core passage. Our findings support two possible hypotheses for the nature of the diffuse radio emission of ZwCl 2341.1+0000: a two relics + halo scenario or diffuse emission associated with the infall and merging of several galaxy groups during the first phase of the cluster formation.

Description: We analyse the dynamical state of Abell 1914, a merging cluster hosting a radio halo, quite unusual for its structure. Our study considers spectroscopic data for 119 galaxies obtained with the Italian Telescopio Nazionale Galileo. We select 89 cluster members from spatial and velocity distributions. We also use photometry Canada–France–Hawaii Telescope archives. We compute the mean cluster redshift, 〈 z 〉 = 0.168, and the velocity dispersion which shows a high value, V = 1210 ${^{+ 125}_{- 110}}$  km s –1 . From the 2D analysis we find that Abell 1914 has a north-east (NE)–south-west (SW) elongated structure with two galaxy clumps, that mostly merge in the plane of the sky. Our best but very uncertain estimate of the velocity dispersion of the main system is V , main  ~ 1000 km s –1 . We estimate a virial mass M sys  = 1.4–2.6 x 10 15 h ${^{- 1}_{70}}$ M for the whole system. We study the merger through a simple two-body model and find that data are consistent with a bound, outgoing substructure observed just after the core crossing. By studying the 2D distribution of the red galaxies, photometrically selected, we show that Abell 1914 is contained in a rich large-scale structure, with two close companion galaxy systems, known to be at z  ~ 0.17. The system at SW supports the idea that the cluster is accreting groups from a filament aligned in the NE–SW direction, while that at NW suggests a second direction of the accretion (NW–SE). We conclude that Abell 1914 well fits among typical clusters with radio haloes. We argue that the unusual radio emission is connected to the complex cluster accretion and suggest that Abell 1914 resembles the well-known nearby merging cluster Abell 754 for its particular observed phenomenology.