Showing papers by "George H. Rieke published in 1988"
TL;DR: In this article, a color-magnitude diagram was used to identify both normal galaxies with z = 0.3-1 and what appears to be a new distinct population, which has properties roughly similar to what would be expected for large galaxies at z greater than six undergoing a rapid luminous phase of star formation.
Abstract: Deep near-infrared imaging was obtained to study extragalactic populations, and a color-magnitude diagram was used to identify both normal galaxies with z = 0.3-1 and what appears to be a new distinct population. The latter has properties roughly similar to what would be expected for large galaxies at z greater than six undergoing a rapid luminous phase of star formation. It is suggested that these galaxies are good candidates for primeval galaxies. The normal galaxies identified are also important for studies of galaxy evolution, since they are found in the near-infrared, which is only weakly affected by evolution of the stellar populations. 17 references.
185 citations
TL;DR: The modest-luminosity, isolated starburst galaxy NGC 253 shows strong shocked molecular hydrogen emission from a 100 pc region centered on its nucleus as discussed by the authors. This emission can arise in an early stage of a nuclear starburst where supernova explosions lead to large amounts of shocked molecular gas through collisions of dense molecular clouds and cloud implosion.
Abstract: The modest-luminosity, isolated starburst galaxy NGC 253 shows strong shocked molecular hydrogen emission from a 100 pc region centered on its nucleus. This emission can arise in an early stage of a nuclear starburst where supernova explosions lead to large amounts of shocked molecular gas through collisions of dense molecular clouds and cloud implosion. Other properties of NGC 253 also indicate it is at a relatively early stage in its starburst. A sequence of starburst development is suggested; examples along this sequence from young to old would include NGC 5253, NGC 253, M82, NGC 4736, and M31. This sequence is based on the expected evolution of a broad variety of observed parameters, and it is consistent with the observed relation between nonthermal radio and thermal infrared luminosities. 48 references.
84 citations
TL;DR: In this article, the authors measured the velocities of 43 stars within 6.5 pc of the Galactic center and found that the stellar velocity dispersion of 75 km/s is virtually independent of radius from 0.36 pc to 6 pc, indicating that an extended mass distribution is being sampled over this entire range.
Abstract: Radial velocities have been measured for 43 stars within 6.5 pc of the Galactic center. The stellar velocity dispersion of 75 km/s is virtually independent of radius from 0.36 pc to 6 pc, indicating that an extended mass distribution is being sampled over this entire range. The stellar velocities do not show the increase within 2 pc of Sgr A(asterisk) found for the gas, suggesting that the gas motions may be affected by nongravitational forces. If the core radius of the stellar distribution is about 0.1 pc, these data require no unseen mass within the Galactic center; however, if the core radius is about 0.6 pc, an unseen mass of 2,000,000 solar masses may still exist. 28 references.
74 citations
TL;DR: Spectres IR (2 a 25 μm) des galaxies NGC 4736, M 81, M 31, M 32, and NGC 3115 were analysed en detail as mentioned in this paper.
Abstract: Spectres IR (2 a 25 μm) des galaxies NGC 4736, M 81, M 31, M 32 et NGC 3115 Le cas de NGC 4736 est analyse en detail Des bandes d'absorption de CO, anormalement fortes, sont mises en evidence et sont interpretees par une flambee d'etoiles puissante mais ancienne dans le noyau de cette galaxie
30 citations
TL;DR: In this article, a modele base sur la Courbe de croissance de la loi de Hubble, modifie par une relation couleur-type morphologique-ouverture, is constructed for decomposer l'emission nucleaire d'origine stellaire and non stellaires d'un echantillon de 16 galaxies de Seyfert de type I.
Abstract: Construction d'un modele base sur la courbe de croissance de la loi de Hubble, modifie par une relation couleur-type morphologique-ouverture, pour decomposer l'emission nucleaire d'origine stellaire et non stellaire d'un echantillon de 16 galaxies de Seyfert de type I
22 citations
Journal Article•
TL;DR: A small helium-cooled IR telescope flown on Spacelab-2 in July/August 1985 was used to make infrared measurements between 2 microns and 120 microns as discussed by the authors.
Abstract: A small helium cooled IR telescope flown on Spacelab-2 in July/August 1985 was used to make infrared measurements between 2 microns and 120 microns. New data were obtained on the structure of the Galaxy at 2 microns and 7 microns showing it to be much broader at these wavelengths than at longer wavelengths. The IR emission due to contamination from the Shuttle was found to be greater than anticipated, indicating the induced environment to be much higher than the planned limits. Aspects of superfluid helium management in zero-G and of a cryogenically cooled telescope design were also tested.
8 citations
27 Apr 1988
TL;DR: The Space Infrared Telescope Facility (SIRTF) project at NASA/Ames Research Center as mentioned in this paper was designed to perform infrared astronomical tasks such as imaging, photometry, and spectroscopy.
Abstract: Concepts of scientific instruments designed to perform infrared astronomical tasks such as imaging, photometry, and spectroscopy are discussed as part of the Space Infrared Telescope Facility (SIRTF) project under definition study at NASA/Ames Research Center. The instruments are: the multiband imaging photometer, the infrared array camera, and the infrared spectograph. SIRTF, a cryogenically cooled infrared telescope in the 1-meter range and wavelengths as short as 2.5 microns carrying multiple instruments with high sensitivity and low background performance, provides the capability to carry out basic astronomical investigations such as deep search for very distant protogalaxies, quasi-stellar objects, and missing mass; infrared emission from galaxies; star formation and the interstellar medium; and the composition and structure of the atmospheres of the outer planets in the solar sytem.
3 citations