Search Publications
Age dating stellar populations in the near infrared: an absolute age indicator from the presence/absence of red supergiants.
Bastian, N.; Adamo, A.; Urbaneja, M. A. +4 more
The determination of age is a critical component in the study of a population of stellar clusters. In this Letter, we present a new absolute age indicator for young massive star clusters based on J-H colour. This novel method identifies clusters as older or younger than 5.7 ± 0.8 Myr based on the appearance of the first population of red supergian…
Ripping apart at the seams: the network of stripped gas surrounding M86
Finoguenov, A.; Simionescu, A.; Allen, S. W. +4 more
We present a new study of the Virgo Cluster galaxies M86, M84, NGC 4338 and NGC 4438 using a mosaic of five separate pointings with XMM-Newton. Our observations allow for robust measurements of the temperature and metallicity structure of each galaxy along with the entire ∼1° region between these galaxies. When combined with multiwavelength observ…
Orbital and evolutionary constraints on the planet hosting binary GJ 86 from the Hubble Space Telescope
Bond, Howard E.; Barstow, M. A.; Holberg, J. B. +5 more
This paper presents new observations of the planet-hosting, visual binary GJ 86 (HR 637) using the Hubble Space Telescope. Ultraviolet and optical imaging with WFC3 confirms the stellar companion is a degenerate star and indicates the binary semimajor axis is larger than previous estimates, with a ≳ 28 au. Optical STIS spectroscopy of the secondar…
A z = 3.045 Lyα emitting halo hosting a QSO and a possible candidate for AGN-triggered star formation.
Carswell, R. F.; Rauch, M.; Becker, G. D. +2 more
In this third paper in a series on the nature of extended, asymmetric Lyα emitters at z ∼ 3 we report the discovery, in an ultra-deep, blind, spectroscopic long-slit survey, of a Lyα emitting halo around a QSO at redshift 3.045. The QSO is a previously known, obscured active galactic nucleus (AGN). The Lyα emitting halo appears extended along the …
1ES 1927+654: a bare Seyfert 2
Fabian, A. C.; Cackett, E. M.; Panessa, F. +3 more
1ES 1927+654 is an active galactic nucleus (AGN) that appears to defy the unification model. It exhibits a type-2 optical spectrum, but possesses little X-ray obscuration. XMM-Newton and Suzaku observations obtained in 2011 are used to study the X-ray properties of 1ES 1927+654. The spectral energy distribution derived from simultaneous optical-to…
X-ray emission from the ultramassive black hole candidate NGC 1277: implications and speculations on its origin.
Fabian, A. C.; Miller, J. M.; Sanders, J. S. +2 more
We study the X-ray emission from NGC 1277, a galaxy in the core of the Perseus cluster, for which van den Bosch et al. have recently claimed the presence of an ultramassive black hole (UMBH) of mass 1.7× 10^{10}{ M_{{⊙}}}, unless the initial mass function of the stars in the stellar bulge is extremely bottom heavy. The X-rays originate in a power-…
An X-ray-UV correlation in Cen X-4 during quiescence
Degenaar, N.; Wijnands, R.; Miller, J. M. +3 more
Quiescent emission from the neutron star low-mass X-ray binary Cen X-4 is seen to be variable on time-scales from hundreds of seconds to years, suggesting that at least in this object, low-level accretion is important during quiescence. Here, we present results from recent XMM-Newton and Swift observations of Cen X-4, where the X-ray flux (0.5-10 …
Discovery of 47-s pulsations in the X-ray source 1RXS J225352.8+624354
Götz, D.; Moretti, A.; Sidoli, L. +5 more
We report on the discovery of pulsations at a period of ∼47 s in the persistent X-ray source 1RXS J225352.8+624354 (1RXS J2253) using five Chandra observations performed in 2009. The signal was also detected in Swift and ROSAT data, allowing us to infer over a 16-yr baseline an average, long-term period increasing rate of ≈17 ms per year and there…
2006 May-July major radio flare episodes in Cygnus X-3: spectrotiming analysis of the X-ray data
Droulans, R.; Koljonen, K. I. I.; Hannikainen, D. C. +1 more
We analyse in detail the X-ray data of the microquasar Cygnus X-3 obtained during major radio flaring episodes in 2006 with multiple observatories. The analysis consists of two parts: probing the fast (∼1 min) X-ray spectral evolution with principal component analysis followed by subsequent spectral fits to the time-averaged spectra (∼3 ks). Based…
A census of quasar-intrinsic absorption in the Hubble Space Telescope archive: systems from high-resolution echelle spectra
Charlton, Jane C.; Masiero, Joseph R.; Tripp, Todd M. +9 more
We present a census of zabs ≲ 2 intrinsic (those showing partial coverage) and associated (zabs ∼ zem) quasar absorption-line systems detected in the Hubble Space Telescope archive of Space Telescope Imaging Spectrograph echelle spectra. This work complements the Misawa et al. survey of 2 < zem < 4…