Search Publications
The Chemical Abundances of Tycho G in Supernova Remnant 1572
Filippenko, Alexei V.; Foley, Ryan J.; Simon, Joshua D. +3 more
We present an analysis of the chemical abundances of the star Tycho G in the direction of the remnant of supernova (SN) 1572, based on Keck high-resolution optical spectra. The stellar parameters of this star are found to be those of a G-type subgiant with T eff = 5900 ± 100 K, log(g/cms2) = 3.85 ± 0.30 dex, and [Fe/H] = -0.0…
MOIRCS Deep Survey. IV. Evolution of Galaxy Stellar Mass Function Back to z ~ 3
Ouchi, M.; Uchimoto, Y. K.; Yamada, T. +11 more
We use very deep near-infrared (NIR) imaging data obtained in MOIRCS Deep Survey (MODS) to investigate the evolution of the galaxy stellar mass function back to z ~ 3. The MODS data reach J = 24.2, H = 23.1, and K = 23.1 (5σ, Vega magnitude) over 103 arcmin2 (wide) and J = 25.1, H = 23.7, and K = 24.1 over 28 arcmin2 (deep) i…
Excitation of Kink Waves Due to Small-Scale Magnetic Reconnection in the Chromosphere?
He, Jiansen; Tian, Hui; Marsch, Eckart +1 more
The kink wave, which has often been observed in coronal loops, is considered as a possibly important energy source contributing to coronal heating. However, its generation has not yet been observed. Here, we report the first observation of kink-wave excitation caused by magnetic reconnection as inferred from Solar Optical Telescope measurements ma…
Measuring the Spin of GRS 1915+105 with Relativistic Disk Reflection
Fabian, A. C.; Miller, J. M.; Homan, J. +5 more
GRS 1915+105 harbors one of the most massive known stellar black holes in the Galaxy. In 2007 May, we observed GRS 1915+105 for ~117 ks in the low/hard state using Suzaku. We collected and analyzed the data with the Hard X-ray Detector/Positive Intrinsic Negative and X-ray Spectrometer cameras spanning the energy range from 2.3 to 55 keV. Fits to …
The Presence of Two Distinct Red Giant Branches in the Globular Cluster NGC 1851
Joo, Seok-Joo; Han, Sang-Il; Kim, Hak-Sub +4 more
There is a growing body of evidence for the presence of multiple stellar populations in some globular clusters, including NGC 1851. For most of these peculiar globular clusters, however, the evidence for the multiple red giant branches (RGBs) having different heavy elemental abundances as observed in ω Centauri is hitherto lacking, although spread…
Hinode Observation of the Magnetic Fields in a Sunspot Light Bridge Accompanied by Long-Lasting Chromospheric Plasma Ejections
Tsuneta, Saku; Shimizu, Toshifumi; Lites, Bruce W. +7 more
We present high-resolution magnetic field measurements of a sunspot light bridge (LB) that produced chromospheric plasma ejections intermittently and recurrently for more than 1 day. The observations were carried out with the Hinode Solar Optical Telescope on 2007 April 29 and 30. The spectro-polarimeter reveals obliquely oriented magnetic fields …
The Environments of High-Redshift Quasi-Stellar Objects
Panagia, N.; Stiavelli, Massimo; Djorgovski, S. G. +9 more
We present a sample of i 775-dropout candidates identified in five Hubble Advanced Camera for Surveys (ACS) fields centered on Sloan Digital Sky Survey quasi-stellar objects (QSOs) at redshift z ~ 6. Our fields are as deep as the GOODS ACS images, which are used as a reference field sample. We find them to be overdense in two fields, un…
The Largest Gravitational Lens: MACS J0717.5+3745 (z = 0.546)
Broadhurst, Tom; Zitrin, Adi; Rephaeli, Yoel +1 more
We identify 13 sets of multiply-lensed galaxies around MACS J0717.5+3745 (z = 0.546), outlining a very large tangential critical curve of major axis ~2farcm8, filling the field of the Hubble Space Telescope/Advanced Camera for Surveys. The equivalent circular Einstein radius is θ e = 55'' ± 3'' (at an estimated source redshift of z
The Survival of Dark Matter Halos in the Cluster Cl 0024+16
Treu, Tommaso; Ellis, Richard; Smail, Ian +5 more
Theories of structure formation in a cold dark matter dominated universe predict that massive clusters of galaxies assemble from the hierarchical merging of lower mass subhalos. Exploiting strong and weak gravitational lensing signals inferred from panoramic Hubble Space Telescope imaging data, we present a high-resolution reconstruction of the ma…
The Environments of Active Galactic Nuclei within the zCOSMOS Density Field
Finoguenov, A.; Kneib, J. -P.; Jahnke, K. +58 more
The impact of environment on active galactic nucleus (AGN) activity up to z ~ 1 is assessed by utilizing a mass-selected sample of galaxies from the 10k catalog of the zCOSMOS spectroscopic redshift survey. We identify 147 AGN by their X-ray emission as detected by XMM-Newton from a parent sample of 7234 galaxies. We measure the fraction of galaxi…