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4 results on '"Meurs, Eja"'

1. EXTENDED SOFT-X-RAY EMISSION IN THE SEYFERT-2 GALAXY NGC-4388 DISCOVERED WITH THE ROSAT HRI

Author

MATT, Giorgio, PIRO L, ANTONELLI LA, FINK HH, MEURS EJA, PEROLA GC, Matt, Giorgio, Piro, L, Antonelli, La, Fink, Hh, Meurs, Eja, and Perola, Gc

Subjects
Astrophysics::High Energy Astrophysical Phenomena, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics::Galaxy Astrophysics
Abstract

Extended (R similar to 4.5 kpc) X-ray emission in the Seyfert 2 galaxy NGC 4388 has been discovered with the ROSAT HRI. No evidence for a nuclear, unresolved component has been found; the upper limit for such a component is about 20% of the total flux. The interpretation of the extended emission in terms of nuclear radiation scattered by a plasma ionized by the nuclear photons can be excluded on the basis of a simple photoionization calculation. The two most likely alternatives, i.e. thermal emission from a collisionally heated plasma and the sum from many unresolved discrete sources, are briefly discussed.

Published
1994

2. STEPS TOWARD DETERMINATION OF THE SIZE AND STRUCTURE OF THE BROAD-LINE REGION IN ACTIVE GALACTIC NUCLEI .1. AN 8 MONTH CAMPAIGN OF MONITORING NGC-5548 WITH IUE

Author

CLAVEL J, REICHERT GA, ALLOIN D, CRENSHAW DM, KRISS G, KROLIK JH, MALKAN MA, NETZER H, PETERSON BM, WAMSTEKER W, ALTAMORE, Aldo, BARIBAUD T, BARR P, BECK S, BINETTE L, BROMAGE GE, BROSCH N, DIAZ AI, FILIPPENKO AV, FRICKE K, GASKELL CM, GIOMMI P, GLASS IS, GONDHALEKAR P, HACKNEY RL, HALPERN JP, HUTTER DJ, JORSATER S, KINNEY AL, KOLLATSCHNY W, KORATKAR A, KORISTA KT, LAOR A, LASOTA JP, LEIBOWITZ E, MAOZ D, MARTIN PG, MAZEH T, MEURS EJA, NAIR AD, OBRIEN P, PELAT D, PEREZ E, PEROLA GC, PTAK RL, RODRIGUEZPASCUAL P, ROSENBLATT EI, SADUN AC, SANTOSLLEO M, SHAW RA, SMITH PS, STIRPE GM, STONER R, SUN WH, ULRICH MH, VANGRONINGEN E, ZHENG W., Clavel, J, Reichert, Ga, Alloin, D, Crenshaw, Dm, Kriss, G, Krolik, Jh, Malkan, Ma, Netzer, H, Peterson, Bm, Wamsteker, W, Altamore, Aldo, Baribaud, T, Barr, P, Beck, S, Binette, L, Bromage, Ge, Brosch, N, Diaz, Ai, Filippenko, Av, Fricke, K, Gaskell, Cm, Giommi, P, Glass, I, Gondhalekar, P, Hackney, Rl, Halpern, Jp, Hutter, Dj, Jorsater, S, Kinney, Al, Kollatschny, W, Koratkar, A, Korista, Kt, Laor, A, Lasota, Jp, Leibowitz, E, Maoz, D, Martin, Pg, Mazeh, T, Meurs, Eja, Nair, Ad, Obrien, P, Pelat, D, Perez, E, Perola, Gc, Ptak, Rl, Rodriguezpascual, P, Rosenblatt, Ei, Sadun, Ac, Santoslleo, M, Shaw, Ra, Smith, P, Stirpe, Gm, Stoner, R, Sun, Wh, Ulrich, Mh, Vangroningen, E, and Zheng, W.

Subjects
Astronomy, Astrophysics
Published
1991

3. Young stellar objects in the IRAS Point Source Catalog

Author

Prusti, T, ADORF, HM, and MEURS, EJA

Subjects
DATA ANALYSIS, NEBULA, STARBURST GALAXIES, LUMINOSITIES, STAR FORMATION, CATALOGS AND DICTIONARIES, STARS, PRE-MAIN-SEQUENCE, T-ASSOCIATION, EMISSION, I DARK CLOUD, INFRARED RADIATION
Abstract

The IRAS Point Source Catalog (IPSC), providing an infrared survey of 96% of the sky, is searched for low mass young stellar objects (YSOs). Three different statistical approaches are pursued to classify an initial set of 69436 sources out of the total of 245889 IPSC objects. The performance of the classifiers is assessed by means of false alarm and hit rates. The similarity, in infrared properties, to a combined sample of YSOs taken from Beichman et al. (1986) and Myers et al. (1987) is exploited by two simple classifiers to produce rank-ordered lists of YSO candidates. A third, two-stage classifier utilizes the infrared properties of galactic and extragalactic objects in conjunction with the clustering properties of YSOs on the sky. This combination considerably improves the discrimination between YSOs and other galactic sources and selects a sample of 5 825 YSO candidates lying outside of confused regions (viz. the galactic plane and the Magellanic clouds). According to our performance analysis 87% or 5068 of these YSO candidates are indeed YSOs (implying a contamination of 13% or 757 misclassified sources), while the selection reaches a completeness of 85%. From these figures-of-merit we can estimate that the initial sample contains in total 5962 YSOs outside the confused areas. The quality of this classification is empirically verified by examining IPSC sources from the initial sample in the well-studied Chamaeleon I star forming region.

Published
1992

4. The extended narrow line region of NGC 4151. I. Emission line ratios and their implications

Author

Penston, M V, Alloin, D, Appenzeller, I, Aretxaga, I, Axon, D J, Baribaud, T, Barthel, P, Baum, S A, Boisson, C, de Bruyn, A G, Clavel, J, Colina, L, Dennefeld, M, Diaz, A, DIETRICH, M, DURRET, F, DYSON, JE, GONDHALEKAR, P, VANGRONINGEN, E, JABLONKA, P, JACKSON, N, KOLLATSCHNY, W, LAURIKAINEN, E, MASEGOSA, J, McHardy, I, MEURS, EJA, MILEY, G, MOLES, M, OBRIEN, P, ODEA, C, DELOLMO, A, PEDLAR, A, PEREA, J, PEREZ, E, Perez-Fournon, I, PERRY, J, PILBRATT, G, REES, M, Robson, I, RODRIGUEZPASCUAL, P, RODRIGUEZ, JM, SANTOSLLEO, M, SCHILIZZI, R, STASINSKA, G, STIRPE, GM, TADHUNTER, C, TERLEVICH, E, TERLEVICH, R, UNGER, S, Vila-vilaro, A, VILCHEZ, J, WAGNER, SJ, WARD, MJ, YATES, GJ, and Kapteyn Astronomical Institute

Published
1990

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