Search Publications
The Sparsest Clusters with O Stars
Oey, M. S.; Werk, J. K.; Lamb, J. B. +1 more
There is much debate on how high-mass star formation varies with environment, and whether the sparsest star-forming environments are capable of forming massive stars. To address this issue, we have observed eight apparently isolated OB stars in the Small Magellanic Cloud (SMC) using Hubble Space Telescope's Advanced Camera for Surveys. Five of the…
The Stellar Kinematic Center and the True Galactic Nucleus of NGC 253
Prieto, M. A.; Acosta-Pulido, J. A.; González-Martín, O. +2 more
We present the first sub-arcsecond resolution two-dimensional stellar kinematics and X-ray observations of the prototypical starburst galaxy NGC 253 which define the position and nature of the galactic nucleus. These observations comprise some of the best probes of the central 300 pc of NGC 253, the nearest massive galaxy undergoing a powerful sta…
Star Formation and UV colors of the Brightest Cluster Galaxies in the Representative XMM-Newton Cluster Structure Survey
Donahue, Megan; Voit, G. Mark; Pierini, Daniele +8 more
We present UV broadband photometry and optical emission-line measurements for a sample of 32 brightest cluster galaxies (BCGs) in clusters of the Representative XMM-Newton Cluster Structure Survey (REXCESS) with z = 0.06-0.18. The REXCESS clusters, chosen to study scaling relations in clusters of galaxies, have X-ray measurements of high quality. …
Quantifying dwarf satellites through gravitational imaging: the case of SDSSJ120602.09+514229.5
Czoske, Oliver; Koopmans, Léon V. E.; Vegetti, Simona
SDSSJ120602.09+514229.5 is a gravitational lens system formed by a group of galaxies at redshift zFG = 0.422 lensing a bright background galaxy at redshift zBG = 2.001. The main peculiarity of this system is the presence of a luminous satellite near the Einstein radius, which slightly deforms the giant arc. This makes SDSSJ12…
Excess AGN activity in the z = 2.30 Protocluster in HS 1700+64
Georgakakis, A.; Nandra, K.; Aird, J. +7 more
We present the results of spectroscopic, narrow-band and X-ray observations of a z = 2.30 protocluster in the field of the QSO HS 1700+643. Using a sample of BX/MD galaxies, which are selected to be at z ~ 2.2-2.7 by their rest-frame ultraviolet colours, we find that there are five protocluster AGN which have been identified by characteristic emis…
Identification of the X-ray Thermal Dominant State in an Ultraluminous X-ray Source in M82
Feng, Hua; Kaaret, Philip
The thermal dominant state in black hole binaries (BHBs) is well understood but rarely seen in ultraluminous X-ray sources (ULXs). Using simultaneous observations of M82 with Chandra and XMM-Newton, we report the first likely identification of the thermal dominant state in a ULX based on the disappearance of X-ray oscillations, low timing noise, a…
IC 2602: a lithium depletion boundary age and new candidate low-mass stellar members
Sharp, R. G.; Lodieu, N.; Dobbie, P. D.
We report the results from a photometric and spectroscopic survey of ∼1.4 deg2 of the young open cluster IC 2602. Fourteen objects have been identified as having magnitudes, spectral types and radial velocities consistent with being probable or possible low-mass stellar members of the cluster. We have used the observed location of the l…
A Massive Runaway Star from 30 Doradus
van Loon, J. Th.; Howarth, I. D.; Massa, D. +7 more
We present the first ultraviolet (UV) and multi-epoch optical spectroscopy of 30 Dor 016, a massive O2-type star on the periphery of 30 Doradus in the Large Magellanic Cloud. The UV data were obtained with the Cosmic Origins Spectrograph on the Hubble Space Telescope as part of the Servicing Mission Observatory Verification program after Servicing…
Microwave Quasi-Periodic Pulsations in Multi-timescales Associated with a Solar Flare/CME Event
Tan, Baolin; Tan, Chengming; Zhang, Yin +1 more
Microwave observations of quasi-periodic pulsations (QPPs) in multi-timescales at the Solar Broadband Radio Spectrometer in Huairou (SBRS/Huairou) on 2006 December 13 are confirmed to be associated with an X3.4 flare/coronal mass ejection (CME) event. It is most remarkable that the timescales of QPPs are distributed in a broad range from hectoseco…
Kuiper belts around nearby stars
Fridlund, M.; Olofsson, G.; Eiroa, C. +10 more
Context. The existence of dusty debris disks around a large fraction of solar type main-sequence stars, inferred from excess far-IR and submillimetre emission compared to that expected from stellar photospheres, suggests that leftover planetesimal belts analogous to the asteroid- and comet reservoirs of the solar system are common.
Aims: Sens…