Science Archives Publication System

Coordinated Cluster, ground-based instrumentation and low-altitude satellite observations of transient poleward-moving events in the ionosphere and in the tail lobe

DOI: 10.5194/angeo-19-1589-2001 Bibcode: 2001AnGeo..19.1589L

Pitout, F.; Balogh, A.; Wild, J. A. +35 more

During the interval between 8:00-9:30 on 14 January 2001, the four Cluster spacecraft were moving from the central magnetospheric lobe, through the dusk sector mantle, on their way towards intersecting the magnetopause near 15:00 MLT and 15:00 UT. Throughout this interval, the EISCAT Svalbard Radar (ESR) at Longyearbyen observed a series of polewa…

2001 • Annales Geophysicae

Cluster 19

Diameters of δ Cephei and η Aquilae Measured with the Navy Prototype Optical Interferometer

DOI: 10.1086/318007 Bibcode: 2001AJ....121..476A

Hajian, Arsen R.; Hummel, C. A.; Germain, M. E. +5 more

We have measured the diameters of the Cepheid variables δ Cephei (18 nights) and η Aquilae (11 nights) with the Navy Prototype Optical Interferometer. The primary results of these observations are the mean angular diameters <θ_LD> of these Cepheids: 1.520+/-0.014 milliseconds of arc (mas) for δ Cep and 1.69+/-0.04 mas for η Aql. We…

2001 • The Astronomical Journal

Hipparcos 19

Ultraviolet Signposts of Resonant Dynamics in the Starburst-ringed SAB Galaxy M94 (NGC 4736)

DOI: 10.1086/319384 Bibcode: 2001AJ....121.1395W

Madore, Barry F.; Keel, William C.; O'Connell, Robert W. +10 more

The dynamic orchestration of star-birth activity in the starburst-ringed galaxy M94 (NGC 4736) is investigated using images from the Ultraviolet Imaging Telescope (UIT; far-ultraviolet [FUV] band), Hubble Space Telescope (HST; near-ultraviolet [NUV] band), Kitt Peak 0.9 m telescope (Hα, R, and I bands), and Palomar 5 m telescope (B band), along wi…

2001 • The Astronomical Journal

IUE eHST 19

Cluster EDI convection measurements across the high-latitude plasma sheet boundary at midnight

DOI: 10.5194/angeo-19-1669-2001 Bibcode: 2001AnGeo..19.1669Q

Baumjohann, W.; Torbert, R. B.; Matsui, H. +15 more

We examine two crossings of three Cluster satellites from the polar cap into the high-latitude plasma sheet at midnight local time, using data from the Electron Drift Instrument (EDI). EDI measures the full electron drift velocity in the plane perpendicular to the magnetic field for any field and drift directions. The context of the measured conve…

2001 • Annales Geophysicae

Cluster 19

The heliosphere after Ulysses

DOI: 10.1023/A:1012260014646 Bibcode: 2001Ap&SS.277..337M

Marsden, R. G.

Launched in October 1990, the ESA-NASA Ulysses mission has conducted the very first survey of the heliosphere within 5 AU of the Sun over the full range of heliolatitudes. With polar passes taking place in 1994 and 1995, the timing of the mission has enabled Ulysses to characterise the global structure of the heliosphere at solar minimum, when the…

2001 • Astrophysics and Space Science

Ulysses 19

The Nuclear Stellar Cluster in the Seyfert 1 Galaxy NGC 3227: High Angular Resolution Near-Infrared Imaging and Spectroscopy

DOI: 10.1086/319052 Bibcode: 2001ApJ...549..254S

Tacconi, L. J.; Schinnerer, E.; Eckart, A.

Near-infrared (NIR) high angular resolution speckle imaging and imaging spectroscopy of the nuclear region (~10^''~840 pc) of the Seyfert 1 galaxy NGC 3227 are presented. The images reveal an unresolved nuclear source in the K band in addition to a nuclear stellar cluster that is slightly resolved in the J and H bands. The contribution o…

2001 • The Astrophysical Journal

eHST 19

Coordinated 1996 HST and IRTF Imaging of Neptune and Triton. I. Observations, Navigation, and Differential Deconvolution

DOI: 10.1006/icar.2000.6562 Bibcode: 2001Icar..149..416S

Baines, K. H.; Sromovsky, L. A.; Fry, P. M. +3 more

On 13-14 August 1996, we carried out the first coordinated contemporaneous imaging of Neptune, using the Hubble Space Telescope (HST) Wide Field Planetary Camera 2 and the NASA Infrared Telescope Facility (IRTF) NSFCAM InSb camera to obtain high spatial resolution absolutely calibrated imagery at wavelengths from 0.2 to 2.5 µm. We used nine …

2001 • Icarus

eHST 19

Discovery of anomalous oxygen isotopic ratios in HR 4049

DOI: 10.1051/0004-6361:20000560 Bibcode: 2001A&A...367L...1C

Yamamura, I.; Cami, J.

We report the discovery in the ISO/SWS spectrum of the post-AGB star HR 4049 of emission bands due to ¹⁷O and ¹⁸O isotopes locked up in CO₂ molecules. It is the first time these isotopomers are detected outside the solar system. Isotopic ratios derived in the optically thin limit are as low as

2001 • Astronomy and Astrophysics

ISO 19

The Continuing Slow Decline of AG Pegasi

DOI: 10.1086/321107 Bibcode: 2001AJ....122..349K

Kenyon, Scott J.; Proga, Daniel; Keyes, Charles D.

We analyze optical and ultraviolet observations of the symbiotic binary AG Pegasi acquired during 1992-1997. The bolometric luminosity of the hot component declined by a factor of 2-3 from 1980-1985 to 1997. Since 1992, the effective temperature of the hot component may have declined by 10%-20%, but this decline is comparable to the measurement er…

2001 • The Astronomical Journal

eHST 19

Long period variable stars: galactic populations and infrared luminosity calibrations

DOI: 10.1051/0004-6361:20010764 Bibcode: 2001A&A...374..968M

Luri, X.; Mowlavi, N.; Mennessier, M. O. +1 more

In this paper HIPPARCOS astrometric and kinematic data are used to calibrate both infrared luminosities and kinematical parameters of Long Period Variable stars (LPVs). Individual absolute K and IRAS 12 and 25 luminosities of 800 LPVs are determined and made available in electronic form. The estimated mean kinematics is analyzed in terms of galact…

2001 • Astronomy and Astrophysics

Hipparcos 19