Engineering topics

Smith, Paul S.

Publications and source records attributed to Smith, Paul S..

23 records · Page 2

NASA NTRS1989

Time-resolved spectroscopy and photometry of the eclipsing AM Herculis binary EXO 033319 - 2554.2

Time-resolved optical observations of the eclipsing AM Herculis binary EXO 033319 - 2554.2 are presented. High-speed photometry of an eclipse is presented and used to derive a new ephemeris for the system and to estimate the size of the region responsible for the cyclotron emission. Optical spectra that span the orbital cycle are presented, the cyclotron emission in these spectra is discussed, and the flux and radial velocity variations of H-beta, H-gamma, and He II 4686 A are examined. Models of the flux and radial velocity variations of the emission lines indicate that about half the line emission comes from low-velocity material that is about 1.4 x 10 to the 10th cm from the white dwarf. The rest comes from high-velocity material that is about 10 to the 10th cm from the white dwarf and is moving toward it at about 600 km/s.

Allen, Richard G.↗

NASA NTRS1988

Circular polarimetry of EXO 033319-2554.2 - A new eclipsing AM Herculis star

This Letter presents circular polarimetry that unequivocally identifies EXO 033319-2554.2 as only the third eclipsing AM Her star and brings the total number of AM Her stars now identified to 14. The orbital period is 126.4 minutes, as previously reported, and defines a new short-period edge to the period gap seen in all classes of cataclysmic variable stars. EXO 033319-2554.2 shows 2.5 mag deep eclipses of the predominantly accreting magnetic pole on the white dwarf. Before the eclipse, the pole rotates into the line of sight and shows white-light circular polarization, due to cyclotron radiation, that reaches values as high as 10 percent. There is some evidence that the second pole is emitting cyclotron radiation too. How high time resolution photometry, linear polarimetry, and spectroscopy will be of great value in understanding this system.

Berriman, Graham↗

NASA NTRS1988

Evidence for accretion disks in highly polarized quasars

The results of a search for thermal components in 11 highly polarized quasars (HPQs) using UVBRI polarimetry and photometry are reported. The 2000-2500 A luminosities of the thermal components are calculated and the estimated luminosities of the broad-line region (BLR) are given in the same wavelength for comparison. The observed optical continua are modeled as a combination of polarized synchrotron emission, unpolarized emission from the BLR, and an unpolarized flat spectral component that may be optically thick thermal emission from an accretion disk. Evidence for thermal emission components is found in three HPQs: PKS 0420-014, B2 1156+295, and 3C 454.3, with marginal evidence in another two, PKS 1510-089 and PKS 2345-167.

Smith, Paul S.↗

NASA NTRS1988

Optical to mid-infrared polarimetry of OH 0739-14

Optical and mid-IR polarimetry and optical photometry are presented for OH 0739 - 14 (= OH 231.8 + 4.2), and previous NIR polarimetry is confirmed. The wavelength dependence of the polarization is modeled. A model using 50-nm silicate grains fits the data at optical and NIR wavelengths but does not do well at the 10-micron silicate feature. The model with 100-nm ice grains fits the data well except at the L band, which is near the 3.08-micron ice absorption feature. The source is most likely to contain a mixture of these two grain species.

Heckert, Paul A.↗

NASA NTRS1987

Optical and near-infrared observations of BL Lacertae objects and active quasars

UBVRI and JHK photometric and polarimetric observations, obtained using the 1.5-m UCSD/UM telescope at Mount Lemmon, AZ during 1982-1984, are reported for a sample of 10 BL Lac objects, eight optically violent variable quasars, and the low-polarization quasar 3C 273. The data are presented in extensive tables and graphs and analyzed in detail. Most of the objects are found to have undergone large polarization variations on time scales ranging from 1 d to several months; five objects had fractional linear polarization P greater than 30 percent at least once during the period of observation, but four never had P greater than 10 percent. Of four objects which exhibited a preferred polarization position angle (theta), three had theta within 20 deg of the jet position angle determined by VLBI.

Smith, Paul S.↗