Search Publications
Hubble Space Telescope Photometry of the Dwarf Spheroidal Galaxy ESO 410-G005
Dolphin, Andrew E.; Grebel, Eva K.; Seitzer, Patrick +7 more
We present Hubble Space Telescope WFPC2 imaging of the nearby low surface brightness dwarf spheroidal galaxy ESO 410-G005, which has been resolved into stars for the first time. The resulting color-magnitude diagram for about 2500 stars shows a red giant branch with a tip at I=22.4+/-0.15 mag, which yields a distance of DMW=1.9+/-0.2 Mp…
NOTE: The Thermal Structure of Triton's Middle Atmosphere
Strobel, D. F.; Franz, O. G.; Elliot, J. L. +3 more
The atmospheric structure of Triton in the altitude range 25-150 km shows an unexpectedly steep thermal gradient of 0.26 K km -1 above 50 km altitude, with a nearly isothermal profile below. The upper part of the profile can be explained by downward conduction of heat deposited by magnetospheric electrons and solar UV. However, the atmo…
Change in photospheric magnetic flux during coronal mass ejections
Gopalswamy, Nat; DeForest, Craig; Lara, Alejandro
We report on the variations of photospheric magnetic flux during coronal mass ejections (CMEs). Using magneograms from the SOHO/MDI instrument, we have computed the magnetic flux of 7 active regions and one disappearing filament region associated with CMEs. When we plotted the flux versus time over a period of few days before, during and after the…
A statistical analysis of the metallicities of nine old superclusters and moving groups
Taylor, B. J.
Using both high-dispersion and low-resolution data, the metallicities of nine old moving groups and superclusters are analyzed. These stellar groupings include the HR 1614 and Hyades superclusters and the Wolf 630, zeta Her, 61 Cyg, HR 1614, sigma Pup, eta Cep, and Arcturus groups. Samples of these stellar groupings are drawn from Eggen's membersh…
On the Nature of Linear Structures in the Helix and Orion Nebulae
O'Dell, C. R.
Linear features of up to 0.25 pc length are seen in both the Helix Nebula and the Orion Nebula. These features are most evident in emission-line ratio images. It is demonstrated that in both objects the features are along projections of lines between the dominant star and an optically thick compact feature (the cometary knots in the Helix and the …
The INES system. III. Evaluation of IUE NEWSIPS high resolution spectra
Altamore, A.; Solano, E.; Wamsteker, W. +2 more
This paper discusses the overall quality of IUE high resolution data processed with the NEWSIPSlinebreak software in terms of flux and wavelength accuracy. It also describes the processing of NEWSIPS high resolution spectra within the framework of the ESA ``IUE Newly Extracted Spectra'' (INES) System. This system provides the IUE high resolution d…
Pre-Orion Cores in the Trifid Nebula
Cernicharo, José; Lefloch, Bertrand
The Trifid Nebula is a young H II region undergoing a burst of star formation. This article reports on far-infrared and millimeter continuum and line observations of several massive and bright protostellar sources in the vicinity of the exciting star of the nebula, just behind the ionization front. These objects are probably young protostars (clas…
Color-Magnitude Sequence in the Clusters at z ~ 1.2 near the Radio Galaxy 3C 324
Terada, Hiroshi; Usuda, Tomonori; Imanishi, Masatoshi +17 more
We have investigated the optical and near-infrared colors of K'-selected galaxies in clusters at z ~ 1.2 near to the radio galaxy 3C 324 using images obtained with the Subaru telescope and archival HST data. The distribution of colors of the galaxies in the cluster region is found to be fairly broad, and it may imply significant scatter in their s…
Temperature Profiles of Accretion Disks around Rapidly Rotating Neutron Stars in General Relativity and the Implications for Cygnus X-2
Misra, Ranjeev; Bhattacharyya, Sudip; Thampan, Arun V. +1 more
We calculate the temperature profiles of (thin) accretion disks around rapidly rotating neutron stars (with low surface magnetic fields), taking into account the full effects of general relativity. We then consider a model for the spectrum of the X-ray emission from the disk that is parameterized by the mass accretion rate, the color temperature, …
Observational Evidence of Supershell Blowout in GS 018-04+44: The Scutum Supershell
Savage, Blair D.; Haffner, L. Matthew; Benjamin, Robert A. +2 more
Emission in the H I 21 cm line has been mapped for a region of the Galaxy that includes two known supershells, GS 018-04+44 and GS 034-06+65. We focus on the GS 018-04+44, hereafter referred to as the Scutum Supershell, which is an elongated shell about 5 deg in diameter extending to -7 deg below the Galactic plane. The Scutum shell lies at a kine…