Search Publications
Two Populations of Young Massive Star Clusters in Arp 220
Wilson, Christine D.; Scoville, N. Z.; Harris, William E. +1 more
We present new optical observations of young massive star clusters in Arp 220, the nearest ultraluminous infrared galaxy, taken in UBVI with the Hubble Space Telescope ACS HRC camera. We find a total of 206 probable clusters whose spatial distribution is centrally concentrated toward the nucleus of Arp 220. We use model star cluster tracks to dete…
Integral Field Spectroscopy of the Luminous Infrared Galaxy Arp 299 (IC 694 + NGC 3690)
Colina, L.; Arribas, S.; Alonso-Herrero, A. +2 more
The luminous infrared galaxy Arp 299 (IC 694 + NGC 3690) is studied using optical integral field spectroscopy obtained with the INTEGRAL system, together with archival Hubble Space Telescope WFPC2 and NICMOS images. The stellar and ionized gas morphology shows λ-dependent variations due to the combined effects of the dust internal extinction and t…
Does the Milky Way Produce a Nuclear Galactic Wind?
Sembach, Kenneth R.; Shull, J. Michael; Danforth, Charles W. +3 more
We detect high-velocity absorbing gas using Hubble Space Telescope and Far Ultraviolet Spectroscopic Explorer medium-resolution spectroscopy along two high-latitude active galactic nucleus (AGN) sight lines (Mrk 1383 and PKS 2005-489) above and below the Galactic center (GC). These absorptions are most straightforwardly interpreted as a wind emana…
Irradiated and Bent Jets in the Orion Nebula
Smith, Nathan; Bally, John; Walawender, Josh +1 more
We present new images and proper-motion measurements of irradiated outflows from young stars in the outskirts of the Orion Nebula obtained with the Advanced Camera for Surveys onboard the Hubble Space Telescope. The images reveal many new outflows and new details in previously detected flows. The large-scale bipolar flows such as HH 502, 505, 874,…
Amorphous alumina in the extended atmosphere of α Orionis
Waters, L. B. F. M.; Eriksson, K.; Hony, S. +7 more
In this paper we study the extended atmosphere of the late-type supergiant α Orionis. Infrared spectroscopy of red supergiants reveals strong molecular bands, some of which do not originate in the photosphere but in a cooler layer of molecular material above it. Lately, these layers have been spatially resolved by near and mid-IR interferometry. I…
Venus-solar wind interaction: Asymmetries and the escape of O+ ions
Kallio, E.; Janhunen, P.; Jarvinen, R.
We study the interaction between Venus and the solar wind using a global three-dimensional self-consistent quasi-neutral hybrid (QNH) model. The model treats ions (H+,O+) as particles and electrons as a massless charge neutralizing fluid. In the analysed Parker spiral interplanetary magnetic field (IMF) case (IMF=[8.09,5.88,0…
COSMOGRAIL: the COSmological MOnitoring of GRAvItational Lenses. II. SDSS J0924+0219: the redshift of the lensing galaxy, the quasar spectral variability and the Einstein rings
Magain, P.; Dye, S.; Meylan, G. +4 more
Aims.To provide the observational constraints required to use the gravitationally lensed quasar SDSS J0924+0219 for the determination of H0 from the time delay method. We measure here the redshift of the lensing galaxy, we show the spectral variability of the source, and we resolve the lensed host galaxy of the source.
Methods.We pr…
The Hard X-Ray 20-40 keV AGN Luminosity Function
Gehrels, N.; Shrader, C. R.; Produit, N. +2 more
We have compiled a complete extragalactic sample based on ~25,000 deg2 to a limiting flux of 3×10-11 ergs cm-2 s-1 (~7000 deg2 to a flux limit of 10-11 ergs cm-2 s-1) in the 20-40 keV band with INTEGRAL. We have constructed a detailed exposure map to compensate…
A variable Quasi-Periodic Oscillation in M82 X-1. Timing and spectral analysis of XMM-Newton and RossiXTE observations
Belloni, T.; Ranalli, P.; Casella, P. +2 more
We report results from a spectral and timing analysis of M82 X-1, one of the brightest known ultraluminous X-ray sources. Data from a new 105-ks XMM-Newton observation of M82 X-1, performed in 2004 April, and of archival RossiXTE observations are presented. A very soft thermal component is present in the XMM spectrum. Although it is not possible t…
Resolving the compact dusty discs around binary post-AGB stars using N-band interferometry
Waters, L. B. F. M.; Jaffe, W.; Paresce, F. +8 more
We present the first mid-IR long baseline interferometric observations of the circumstellar matter around binary post-AGB stars. Two objects,