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Unconstrained Astrometric Orbits for Hipparcos Stars with Stochastic Solutions
Makarov, V. V.; Goldin, A.
A considerable number of astrometric binaries whose positions on the sky do not obey the standard model of mean position, parallax, and linear proper motion were observed by the Hipparcos satellite. Some of them remain undiscovered, and their observational data have not been properly processed with the more adequate astrometric model that includes…
The Low-Redshift Lyα Forest toward PKS 0405-123
Tripp, Todd M.; Jenkins, Edward B.; Davé, Romeel +5 more
We present results for Lyα forest and metal absorbers from ~7 km s-1 resolution Space Telescope Imaging Spectrograph data for QSO PKS 0405-123 (z=0.574). We analyze strong and weak samples of Lyα forest lines, containing 60 absorbers with column density logNHI>=13.3 over 0.002<z<0.423 and 44 with logNHI>…
Solar Neutron Events of 2003 October-November
Lopate, C.; Kudela, K.; Watanabe, K. +14 more
During the period when the Sun was intensely active in 2003 October-November, two remarkable solar neutron events were observed by the ground-based neutron monitors. On 2003 October 28, in association with an X17.2 large flare, solar neutrons were detected with high statistical significance (6.4 σ) by the neutron monitor at Tsumeb, Namibia. On 200…
A Burst and Simultaneous Short-Term Pulsed Flux Enhancement from the Magnetar Candidate 1E 1048.1-5937
Kaspi, Victoria M.; Woods, Peter M.; Gavriil, Fotis P.
We report on the 2004 June 29 X-ray burst detected from the direction of the AXP 1E 1048.1-5937 using the RXTE. We find a simultaneous increase of ~3.5 times the quiescent value in the 2-10 keV pulsed flux of 1E 1048.1-5937 during the tail of the burst, which identifies the AXP as the burst's origin. The burst was overall very similar to the two o…
Searches for diffuse X-ray emission around millisecond pulsars: an X-ray nebula associated with PSR J2124-3358
Hui, C. Y.; Becker, W.
We report on diffuse X-ray emission associated with the nearby solitary millisecond pulsar PSR J2124-3358 detected with XMM-Newton and Chandra. The emission extends from the pulsar to the northwest by ~ 0.5 arcmin. The spectrum of the nebular emission can be modeled with a power-law of photon index 2.2±0.4, in line with the emission originating fr…
Geologically recent tectonic, volcanic and fluvial activity on the eastern flank of the Olympus Mons volcano, Mars
Head, J. W.; Neukum, G.; van Gasselt, S. +4 more
We show evidence of very recent (<=25-40 Myr) geologic activity on the eastern flank of Olympus Mons volcano that includes a suite of fluvial (channel networks), volcanic (emplacement of lava flows and dikes), and tectonic (wrinkle ridges and troughs) processes. The combination and youth of these features confirms the importance of geological a…
X-ray spectra of sources in the 13H XMM-Newton/Chandra deep field
McHardy, I.; Page, M. J.; Seymour, N. +8 more
We present the X-ray spectra of 86 optically identified sources in the 13H XMM-Newton/Chandra deep field which have >70 X-ray counts. The majority of these sources have 2-10keV fluxes between 10-15 and 5 × 10-14ergcm-2s-1. The sample consists of 50 broad-line active galactic nuclei (BLAGN),…
Rotational Broadening of Atomic Spectral Features from Neutron Stars
Chang, Philip; Bildsten, Lars; Morsink, Sharon +1 more
The discovery of the first gravitationally redshifted spectral line from a neutron star (NS) by Cottam et al. has triggered theoretical studies of the physics of atomic line formation in NS atmospheres. Chang et al. showed that the hydrogenic Fe Hα line formed above the photosphere of a bursting NS is intrinsically broad. We now include rotational…
The O VI Absorbers toward PG 0953+415: High-Metallicity, Cosmic-Web Gas Far from Luminous Galaxies
Bowen, David V.; Tripp, Todd M.; Jenkins, Edward B. +1 more
The spectrum of the low-redshift QSO PG 0953+415 (zQSO=0.234) shows two strong, intervening O VI absorption systems. To study the nature of these absorbers, we have used the Gemini Multi-Object Spectrograph to conduct a deep spectroscopic galaxy redshift survey in the 5'×5' field centered on the QSO. This survey is fully complete for r'…
The Light Echo around Supernova 2003gd in Messier 74
Van Dyk, Schuyler D.; Filippenko, Alexei V.; Li, Weidong
We confirm the discovery of a light echo around the Type II-plateau supernova 2003gd in Messier 74 (NGC 628), seen in images obtained with the High Resolution Channel of the Advanced Camera for Surveys on board the Hubble Space Telescope (HST) as part of a larger Snapshot program on the late-time emission from supernovae. The analysis of the echo …