Science Archives Publication System

What Is Happening at Spectral Type F5 in Hyades F Stars?

DOI: 10.1086/339395 Bibcode: 2002ApJ...569..941B

Carpenter, Kenneth; Robinson, Richard; Böhm-Vitense, Erika +1 more

Aiming at a better understanding of the mechanisms heating the chromospheres, transition regions, and coronae of cool stars, we study ultraviolet, low-resolution Hubble Space Telescope/Space Telescope Imaging Spectrograph spectra of Hyades main-sequence F stars. We study the B-V dependence(s) of the chromospheric and transition layer emission line…

2002 • The Astrophysical Journal

IUE eHST 18

Astrometry and Near-Infrared Photometry of Neptune's Inner Satellites and Ring Arcs

DOI: 10.1086/339022 Bibcode: 2002AJ....123.1776D

Schneider, Glenn; Dumas, Christophe; Terrile, Richard J. +1 more

We report 1.87 µm photometry and astrometry of the inner satellites (Proteus, Larissa, Galatea, and Despina) and ring arcs of Neptune, obtained with the Hubble Space Telescope and its near-infrared camera NICMOS. From comparison with the Voyager data obtained at visible wavelengths, the small bodies orbiting within the ring region of Neptune…

2002 • The Astronomical Journal

eHST 18

The enigmatic WR46: A binary or a pulsator in disguise. II. The spectroscopy

DOI: 10.1051/0004-6361:20020075 Bibcode: 2002A&A...385..600V

Crowther, P. A.; van der Hucht, K. A.; van Genderen, A. M. +1 more

We present spectroscopic monitoring of the Wolf-Rayet (WR) star WR 46 between 1989 and 1998, which has been obtained simultaneously with multicolour photometry (Veen et al. \cite{Veen02a}, Paper I). The spectroscopic monitoring data show that the radiative fluxes of the optical emission lines (O Vi 3811/34, O Vi 5290, N V 4944, …

2002 • Astronomy and Astrophysics

IUE 18

First orbital elements for the lambda Bootis spectroscopic binary systems HD 84948 and HD 171948. Implications for the origin of the lambda Bootis stars

DOI: 10.1051/0004-6361:20011559 Bibcode: 2002A&A...381..914I

Kamp, I.; Paunzen, E.; Claret, A. +4 more

We present high-resolution spectroscopic observations of the two lambda Bootis type spectroscopic binary systems HD 84948 and HD 171948. Both systems consist of two true lambda Bootis stars, as has already been proven by a detailed abundance analysis taking into account the binary nature. Nevertheless, we have obtained non-LTE abundances for carbo…

2002 • Astronomy and Astrophysics

Hipparcos 18

How much of the solar irradiance variations is caused by the magnetic field at the solar surface?

DOI: 10.1016/S0273-1177(02)00238-7 Bibcode: 2002AdSpR..29.1933S

Solanki, S. K.; Fligge, M.

The contribution to total solar irradiance variations by the magnetic field at the solar surface is estimated. Detailed models of the irradiance changes on the basis of magnetograms show that magnetic features at the solar surface account for over 90% of the irradiance variations on a solar rotation time scale and at least 70% on a solar cycle tim…

2002 • Advances in Space Research

SOHO 18

Observations of Mira stars with the IOTA/FLUOR interferometer and comparison with Mira star models

DOI: 10.1016/S1384-1076(01)00085-9 Bibcode: 2002NewA....7....9H

Beckmann, U.; Weigelt, G.; Hofmann, K. -H. +16 more

We present K'-band observations of five Mira stars with the IOTA interferometer. The interferograms were obtained with the FLUOR fiber optics beam combiner, which provides high-accuracy visibility measurements in spite of time-variable atmospheric conditions. For the M-type Miras X Oph, R Aql, RU Her, R Ser, and the C-type Mira V CrB we derived th…

2002 • New Astronomy

Hipparcos 18

Aging of Titan's Aerosols

DOI: 10.1006/icar.2001.6802 Bibcode: 2002Icar..156..530D

Dimitrov, Vasili; Bar-Nun, Akiva

Titan's haze is composed of aerosols containing long chain polymers of acetylene with some hydrogen cyanide. These polymers have alternating double/single and triple/single bonds, which can open spontaneously or under the action of UV radiation or particle impact. Once opened, they can induce the opening of a double or triple bond in an adjacent c…

2002 • Icarus

Huygens 18

A Precise Orbit Determination of χ¹ Orionis from Astrometric and Radial Velocity Data

DOI: 10.1086/338367 Bibcode: 2002PASP..114..224H

Han, Inwoo; Gatewood, George

We have derived an accurate orbit of χ¹ Orionis (HD 39587, HIP 27913, HR 2047) by combining precise astrometric and radial velocity data. The combined orbital analysis yields P=5156.7+/-2.5 days, K₁=1.885+/-0.004 km s^-1, α₁=94.8+/-1.6 mas, e=0.451+/-0.003, and mass ratio (M₂/M₁) q=0…

2002 • Publications of the Astronomical Society of the Pacific

Hipparcos 18

Discovery of an Extremely Red Object in the Field of HD 155826

DOI: 10.1086/339722 Bibcode: 2002ApJ...570..779L

Djorgovski, S. G.; Christian, D. J.; Gorjian, V. +7 more

We have discovered an extremely red object, LSF 1, located 7" southwest (P.A. 217°) of the bright spectroscopic binary system HD 155826. Originally reported by IRAS as one source detected at 12-60 µm, and found as a single 6-25 µm source of similar flux in the Midcourse Space Experiment Galactic plane survey, two bright point sources w…

2002 • The Astrophysical Journal

eHST 18

Fast acceleration of a CME-related X-ray structure in the low solar corona

DOI: 10.1029/2001GL013670 Bibcode: 2002GeoRL..29.1403A

Nitta, Nariaki V.; Alexander, David; Metcalf, Thomas R.

We report on a unique observation of the early and rapid acceleration of a fast CME in the low solar corona. The coronal disturbance associated with a LASCO CME and concurrent X1.2 flare on 1998 April 23 was well-observed by the Yohkoh Soft X-ray Telescope. The X-ray observations clearly show an accelerating structure, reaching 800-1100 km/s in ~5…

2002 • Geophysical Research Letters

SOHO 18