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QSO 2359-1241: A Bright, Highly Polarized, Radio-moderate, Reddened, Low-Ionization Broad Absorption Line Quasar

DOI: 10.1086/318243 Bibcode: 2001ApJ...546..134B

Gregg, Michael D.; Becker, R. H.; Arav, Nahum +5 more

We report the discovery of a bright quasar (E=15.8, z=0.868) associated with the flat-spectrum radio source NVSS J235953-124148. This quasar, which we designate QSO 2359-1241, possesses a rare combination of extreme properties that make it of special interest. These properties include intrinsic high-velocity outflow seen in absorption for both hig…

2001 • The Astrophysical Journal

eHST 31

Topology of the Galaxy Distribution in the Hubble Deep Fields

DOI: 10.1086/320640 Bibcode: 2001ApJ...553...33P

Park, Changbom; Gott, J. Richard, III; Choi, Y. J.

We have studied topology of the distribution of the high-redshift galaxies identified in the Hubble Deep Field (HDF) North and South. The two-dimensional genus is measured from the projected distributions of the HDF galaxies at angular scales from 3.8" to 6.1". We have also divided the samples into three redshift slices with roughly equal numbers …

2001 • The Astrophysical Journal

eHST 31

Rapid Submillimeter Brightenings Associated with a Large Solar Flare

DOI: 10.1086/318932 Bibcode: 2001ApJ...548L..95K

Rovira, M.; Costa, J. E. R.; Levato, H. +8 more

We present high time resolution observations of Active Region 8910 obtained simultaneously at 212 and 405 GHz during a large Hα flare, which produced a soft X-ray class X1.1 event. Data were obtained with the new solar submillimeter telescope recently installed at the El Leoncito Observatory to explore this poorly known part of the solar emission …

2001 • The Astrophysical Journal

SOHO 31

Scattered Light Models of Protostellar Envelopes: Multiple Outflow Cavities and Misaligned Circumstellar Disks

DOI: 10.1086/323060 Bibcode: 2001ApJ...561..299W

Wood, Kenneth; Wolff, Michael J.; Bjorkman, Karen S. +4 more

Ground-based imaging, imaging polarimetry, and recent Hubble Space Telescope WFPC2 and NICMOS images of protostars have revealed very complex scattered light patterns that cannot be entirely explained by two-dimensional radiation transfer models. We present here for the first time radiation transfer models of T Tau and IRAS 04016+2610 that are ful…

2001 • The Astrophysical Journal

eHST 31

The Planetary Nebula A39: An Observational Benchmark for Numerical Modeling of Photoionized Plasmas

DOI: 10.1086/322489 Bibcode: 2001ApJ...560..272J

Korista, Kirk T.; Jacoby, George. H.; Ferland, Gary. J.

Galactic nebulae are the main probes for the chemical evolution of the interstellar medium. Yet, recent observations have shown that chemical abundances determined from recombination and collisionally excited emission lines can differ by as much as an order of magnitude in some planetary nebulae (PNs). Many PNs have complex geometries and morpholo…

2001 • The Astrophysical Journal

eHST 30

A Spectroscopic Study of Component C and the Extended Emission around I Zw 18

DOI: 10.1086/322494 Bibcode: 2001ApJ...560..222I

Green, Richard F.; Chaffee, Frederic H.; Thuan, Trinh X. +5 more

Long-slit Keck II,1 4 m Kitt Peak,2 and 4.5 m MMT3 spectrophotometric data are used to investigate the stellar population and the evolutionary status of I Zw 18C, the faint C component of the nearby blue compact dwarf galaxy I Zw 18. Hydrogen Hα and Hβ emission lines are detected in the spectra of I Zw 18C, which implies that ionizing massive star…

2001 • The Astrophysical Journal

eHST 30

Reconciling Extreme-Ultraviolet and Radio Observations of the Sun's Corona

DOI: 10.1086/323212 Bibcode: 2001ApJ...561..396Z

Zhang, J.; Kundu, M. R.; White, S. M. +2 more

The Sun's corona, which is composed of plasma at a temperature of a few millions of degrees, can be best viewed in two electromagnetic domains, one from wavelengths of a few angstroms to hundreds of angstroms (in the soft X-ray and EUV domain), the other from wavelengths of a few centimeters to several tens of centimeters (in the radio domain). In…

2001 • The Astrophysical Journal

SOHO 30

Identification and Analysis of Young Star Cluster Candidates in M31

DOI: 10.1086/322424 Bibcode: 2001ApJ...559..851W

Williams, Benjamin F.; Hodge, Paul W.

We present a method for finding clusters of young stars in M31 using broadband WFPC2 data from the HST data archive. Applying our identification method to 13 WFPC2 fields, covering an area of ~60 arcmin², has revealed 79 new candidate young star clusters in these portions of the M31 disk. Most of these clusters are small (<~5 pc), yo…

2001 • The Astrophysical Journal

eHST 30

Water Production of Comets 2P/Encke and 81P/Wild 2 Derived from SWAN Observations during the 1997 Apparition

DOI: 10.1006/icar.2001.6637 Bibcode: 2001Icar..152..268M

Schmidt, W.; Bertaux, J. -L.; Lallement, R. +5 more

The water production rates of comets 2P/Encke and 81P/Wild 2 during their 1997 apparitions have been estimated from Lyman-α observations of the SWAN instrument and compared to previously published values. 2P/Encke was detected 28 times from few days preperihelion to 1.4 AU postperihelion with a perihelion water production rate Q_{H ₂…}

2001 • Icarus

SOHO 30

A complete relativistic ionized accretion disc in Cygnus X-1

DOI: 10.1046/j.1365-8711.2001.04498.x Bibcode: 2001MNRAS.325.1045Y

Young, A. J.; Fabian, A. C.; Ross, R. R. +1 more

The galactic black hole candidate Cygnus X-1 is observed to be in one of two X-ray spectral states: either the low/hard (low soft X-ray flux and a flat power-law tail) or high/soft (high blackbody-like soft X-ray flux and a steep power-law tail) state. The physical origin of these two states is unclear. We present here a model of an ionized accret…

2001 • Monthly Notices of the Royal Astronomical Society

Exosat 30