Search Publications
The Contribution of Primordial Binaries to the Blue Straggler Population in 47 Tucanae
Ferraro, Francesco R.; Sills, Alison; Beccari, Giacomo +5 more
Recent observations of the blue straggler population in 47 Tucanae give the first detailed characterization of their spatial distribution in the cluster over its entire volume. Relative to the light distribution, blue stragglers appear to be overabundant in the core and at large radii. The observed surface density profile shows a central peak, a z…
Dust and Diffuse Interstellar Bands in the za = 0.524 Absorption System toward AO 0235+164
Cohen, Ross D.; Burbidge, E. M.; Lyons, R. W. +3 more
We present new Hubble Space Telescope (HST) Space Telescope Imaging Spectrograph (STIS) NUV-MAMA and STIS CCD observations of the BL Lac object AO 0235+164 and the intervening damped Lyα (DLA) line at za=0.524. The line profile gives N(HI)=(5+/-1)×1021 cm-2 and, combined with the H I 21 cm absorption data, leads to…
High-Redshift Extremely Red Objects in the Hubble Space Telescope Ultra Deep Field Revealed by the GOODS Infrared Array Camera Observations
Dickinson, Mark; Ferguson, Henry C.; Grogin, Norman A. +9 more
Using early data from the Infrared Array Camera (IRAC) on the Spitzer Space Telescope, taken for the Great Observatories Origins Deep Survey (GOODS), we identify and study objects that are well detected at 3.6 µm but are very faint (and in some cases, invisible) in the Hubble Ultra Deep Field (HUDF) ACS and NICMOS images and in very deep VLT…
High Energy Transient Explorer 2 Observations of the Extremely Soft X-Ray Flash XRF 020903
Sakamoto, T.; Yamauchi, M.; Cline, T. +36 more
We report High Energy Transient Explorer 2 (HETE-2) Wide Field X-Ray Monitor/French Gamma Telescope observations of the X-ray flash XRF 020903. This event was extremely soft: the ratio log(SX/Sγ)=0.7, where SX and Sγ are the fluences in the 2-30 and 30-400 keV energy bands, is the most extreme value obse…
A Study of the Reionization History of Intergalactic Helium with FUSE and the Very Large Telescope
Kruk, J. W.; Shull, J. M.; Zheng, W. +8 more
We obtained high-resolution Far Ultraviolet Spectroscopic Explorer (FUSE; R~20,000) and Very Large Telescope (VLT; R~45,000) spectra of the quasar HE 2347-4342 in order to study the properties of the intergalactic medium between redshifts z=2.0 and 2.9. The high-quality optical spectrum allows us to identify approximately 850 H I absorption lines …
The Structure of the Local Interstellar Medium. III. Temperature and Turbulence
Redfield, Seth; Linsky, Jeffrey L.
We present 50 individual measurements of the gas temperature and turbulent velocity in the local interstellar medium (LISM) within 100 pc. By comparing the absorption line widths of many ions with different atomic masses, we can satisfactorily discriminate between the two dominant broadening mechanisms, thermal broadening and macroscopic nontherma…
The Optical/Near-Infrared Counterpart of the INTEGRAL Obscured Source IGR J16318-4848: An sgB[e] in a High-Mass X-Ray Binary?
Filliatre, P.; Chaty, S.
The X-ray source IGR J16318-4848 was the first source discovered by INTEGRAL on 2003 January 29. The high-energy spectrum exhibits such a high column density that the source is undetectable in X-rays below 2 keV. On 2003 February 23-25, we triggered our Target of Opportunity (ToO) program using the EMMI and SOFI instruments on the New Technology T…
Ultra-High-Precision Velocity Measurements of Oscillations in α Centauri A
Butler, R. Paul; Bedding, Timothy R.; Marcy, Geoffrey W. +5 more
We have made differential radial velocity measurements of the star α Centauri A using two spectrographs, the UV-Visual Echelle Spectrograph (UVES) and the University College London Echelle Spectrograph (UCLES), both with iodine absorption cells for wavelength referencing. Stellar oscillations are clearly visible in the time series. After removing …
Observing the Formation of the Hubble Sequence in the Great Observatories Origins Deep Survey
Grogin, Norman A.; Lucas, Ray A.; Ravindranath, Swara +6 more
Understanding the physical formation of the Hubble sequence remains one of the most important unsolved astrophysical problems. Searches for protodisks and proto-elliptical galaxies can now be effectively done using deep wide-field Hubble Space Telescope images taken with the new Advanced Camera for Surveys. Through an analysis of the concentration…
The Fluctuating Intergalactic Radiation Field at Redshifts z = 2.3-2.9 from He II and H I Absorption toward HE 2347-4342
Shull, J. Michael; Kriss, Gerard A.; Tumlinson, Jason +2 more
We provide an in-depth analysis of the He II and H I absorption in the intergalactic medium (IGM) at redshifts z=2.3-2.9 toward HE 2347-4342, using spectra from the Far Ultraviolet Spectroscopic Explorer and the Ultraviolet-Visual Echelle Spectrograph on the Very Large Telescope. Following up on our earlier study, we focus here on two major topics…