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Gemini Spectroscopic Survey of Young Star Clusters in Merging/Interacting Galaxies. I. NGC 3256 Tidal Tail Clusters
Schweizer, François; Miller, Bryan W.; Trancho, Gelys +1 more
We present Gemini optical spectroscopy of three young star clusters in the western tidal tail of NGC 3256. Compact star clusters (as opposed to dwarf galaxy candidates) in tidal tails are rare, and these three clusters are the first for which detailed quantitative spectroscopy has ever been obtained. We find that two of these clusters appear to be…
Radius-dependent Luminosity Evolution of Blue Galaxies in GOODS-N
Faber, S. M.; Koo, D. C.; Melbourne, J. +3 more
We examine the radius-luminosity (R-L) relation for blue galaxies in the Team Keck Redshift Survey (TKRS) of GOODS-N. We compare with a volume-limited, Sloan Digital Sky Survey sample and find that the R-L relation has evolved to lower surface brightness since z=1. Based on the detection limits of GOODS, this cannot be explained by incompleteness …
Lost and Found: A New Position and Infrared Counterpart for the X-Ray Binary Scutum X-1
Erb, Dawn K.; Chakrabarty, Deepto; Moon, Dae-Sik +5 more
Using archival X-ray data, we find that the catalog location of the X-ray binary Scutum X-1 (Sct X-1) is incorrect and that the correct location is that of the X-ray source AX J183528-0737, which is 15' to the west. Our identification is made on the basis of the 112 s pulse period for this object detected in an XMM-Newton observation, as well as s…
Emission Line Variability of the Accreting Young Brown Dwarf 2MASSW J1207334-393254: From Hours to Years
Stelzer, Beate; Jayawardhana, Ray; Scholz, Alexander
We have obtained a series of high-resolution optical spectra for 2MASSW J1207334-393254 (2M 1207). Two consecutive observing nights at the ESO Very Large Telescope with the Ultraviolet and Visual Echelle Spectrograph yielded a time series with a resolution of ~12 minutes. Additional high-resolution optical spectra were obtained months apart at the…
Lyα Absorption from Heliosheath Neutrals
Wood, Brian E.; Linsky, Jeffrey L.; Izmodenov, Vladislav V. +1 more
We assess the information that HST observations of stellar Lyα lines can provide on the heliosheath, the region of the heliosphere between the termination shock and heliopause. To search for evidence of heliosheath absorption, we conduct a systematic inspection of stellar Lyα lines reconstructed after correcting for ISM absorption (and heliospheri…
Ultracompact Dwarf Candidates in the Hydra Cluster
Harris, William E.; Wehner, Elizabeth M. H.
NGC 3311, the giant cD galaxy in the Hydra Cluster (A1060), has one of the largest globular cluster systems known. We describe new Gemini GMOS (g', i') photometry of the NGC 3311 field which reveals that the red, metal-rich side of its globular cluster population extends smoothly upward into the mass range associated with the…
Dependence of Heliospheric Lyα Absorption on the Interstellar Magnetic Field
Wood, Brian E.; Linsky, Jeffrey L.; Izmodenov, Vladislav V. +1 more
We use newly developed three-dimensional kinetic MHD models of the heliosphere to predict heliospheric H I Lyα absorption for various lines of sight. These predictions are compared with actual Lyα spectra from the Hubble Space Telescope, many of which have yielded previous detections of heliospheric absorption. We find that the absorption predicte…
Multiobject Spectroscopy of Young Star Clusters in NGC 4676
Kewley, Lisa J.; Chambers, Kenneth C.; Barnes, Joshua E. +1 more
Galaxy interactions are known to trigger starbursts. The young star clusters formed in mergers may be young globular clusters. The ages of these young star clusters yield the timing of interaction-triggered star formation and provide an important way to reconstruct the history of merging galaxies. Here we present the first results from our investi…
Are Moreton Waves Coronal Phenomena?
Balasubramaniam, K. S.; Pevtsov, A. A.; Neidig, D. F.
We report on permeability characteristics of the upper solar atmosphere due to the progression of a Moreton wave. An exceptional Moreton wave is tracked to cover most of the Sun, following an unusually large solar X-ray flare observed on 2003 October 29. Using Hα intensity and Doppler measurements, the Moreton wave is tracked for as long as 12 min…
INTEGRAL Spectral Variability Study of the Atoll 4U 1820-30: First Detection of Hard X-Ray Emission
Ubertini, P.; Bazzano, A.; Tarana, A. +1 more
We study the 4-200 keV spectral and temporal behavior of the low-mass X-ray binary 4U 1820-30 with INTEGRAL during 2003-2005. This source as been observed in both the soft (banana) and hard (island) spectral states. A high-energy tail, above 50 keV, in the hard state has been observed for the first time. This places the source in the category of X…