Search Publications
The ring nebula around the blue supergiant SBW1: pre-explosion snapshot of an SN 1987A twin
Filippenko, Alexei V.; Smith, Nathan; Ginsburg, Adam +2 more
SBW1 is a B-type supergiant surrounded by a ring nebula that is a nearby twin of SN 1987A's progenitor and its circumstellar ring. We present images and spectra of SBW1 obtained with the Hubble Space Telescope (HST), the Spitzer Space Telescope and Gemini South. HST images of SBW1 do not exhibit long Rayleigh-Taylor (RT) fingers, which are presume…
Stellar haloes of disc galaxies at z ∼ 1
Trujillo, Ignacio; Bakos, Judit
Taking advantage of the ultradeep near-infrared imaging obtained with the Hubble Space Telescope on the Hubble Ultra Deep Field, we detect and explore for the first time the properties of the stellar haloes of two Milky Way-like galaxies at z ∼ 1. We find that the structural properties of those haloes (size and shape) are similar to the ones found…
Nebular spectroscopy of the nearby Type IIb supernova 2011dh
Van Dyk, Schuyler D.; Filippenko, Alexei V.; Cenko, S. Bradley +6 more
We present nebular spectra of the nearby Type IIb supernova (SN) 2011dh taken between 201 and 678 d after core collapse. At these late times, SN 2011dh exhibits strong emission lines including a broad and persistent Hα feature. New models of the nebular spectra confirm that the progenitor of SN 2011dh was a low-mass giant (M ≈ 13-15 M⊙)…
Constraining thermal dust emission in distant galaxies with number counts and angular power spectra
Bond, J. R.; Dunkley, J.; Addison, G. E.
We perform a joint fit to differential number counts from Spitzer's Multiband Imaging Photometer for Spitzer and Herschel's Spectral and Photometric Imaging Receiver (SPIRE) instruments, and angular power spectra of cosmic infrared background (CIB) anisotropies from SPIRE, Planck, the Atacama Cosmology Telescope and the South Pole Telescope, which…
The complex nature of the nuclear star cluster in FCC 277
Jordán, Andrés; van de Ven, Glenn; Infante, Leopoldo +6 more
Recent observations have shown that compact nuclear star clusters (NSCs) are present in up to 80 per cent of galaxies. However, detailed studies of their dynamical and chemical properties are confined mainly to spiral galaxy hosts, where they are more easily observed. In this paper, we present our study of the NSC in FCC 277, a nucleated elliptica…
On spectral line profiles in Type Ia supernova spectra
Foley, Ryan J.
We present a detailed analysis of spectral line profiles in Type Ia supernova (SN Ia) spectra. We focus on the feature at ∼3500-4000 Å, which is commonly thought to be caused by blueshifted absorption of Ca H&K. Unlike some other spectral features in SN Ia spectra, this feature often has two overlapping (blue and red) components. It is accepte…
The outer halo of the nearest giant elliptical: a VLT/VIMOS survey of the resolved stellar populations in Centaurus A to 85 kpc
Jablonka, P.; Crnojević, D.; Bernard, E. J. +4 more
We present the first survey of resolved stellar populations in the remote outer halo of our nearest giant elliptical (gE), Centaurus A (D = 3.8 Mpc). Using the VIsible Multi Object Spectrograph (VIMOS)/Very Large Telescope (VLT) optical camera, we obtained deep photometry for four fields along the major and minor axes at projected elliptical radii…
A bright ultraluminous X-ray source in NGC 5907
Sutton, Andrew D.; Roberts, Timothy P.; Goad, Michael R. +4 more
We present a multimission X-ray analysis of a bright (peak observed 0.3-10 keV luminosity of ∼6 × 1040 erg s-1), but relatively highly absorbed ultraluminous X-ray source (ULX) in the edge-on spiral galaxy NGC 5907. The ULX is spectrally hard in X-rays (Γ ∼ 1.2-1.7, when fitted with an absorbed power law), and has a previousl…
Milliarcsec-scale radio emission of ultraluminous X-ray sources: steady jet emission from an intermediate-mass black hole?
Farrell, S. A.; Mezcua, M.; Gladstone, J. C. +1 more
The origin of the high X-ray luminosities of most ultraluminous X-ray sources (ULXs) still remains poorly understood. Most of the scenarios proposed to explain their nature assume that ULXs are powered by accretion on to a black hole (BH). In this case, the detection of compact radio emission and the location of the ULXs in the Fundamental Plane (…
Phase-resolved ultraviolet spectroscopy of the magnetic Of?p star HD 191612
Bouret, J. -C.; Howarth, I. D.; Wade, G. A. +5 more
We present for the first time phase-resolved ultraviolet (UV) spectroscopy of an Of?p star, namely, HD 191612. The observations were acquired with the Space Telescope Imaging Spectrograph (STIS) onboard the Hubble Space Telescope (HST). We report the variability observed in the main photospheric and wind features and compare the results with previ…