Engineering topics

Tytler, D.

Publications and source records attributed to Tytler, D..

2 records

NASA NTRS1988

The Geminga X-ray counterpart and a blue optical identification

Based on optical photometry, the identification of the X-ray source 1E 0630+178 with a blue object inside the Einstein error circle is reported. The question of whether the X-rays could be thermal emission from the surface of a neutron star is addressed. The new optical data confirm that relative fluxes in the optical, X-ray, and gamma-ray bands closely match those of the Vela pulsar. The Vela pulsar is adopted as an 'observational model' for Geminga, whereby only the lack of radio emission from Geminga remains to be accounted for. Previous observational results and theoretical models for Geminga are reviewed in light of the new findings.

Halpern, J. P.↗

NASA NTRS1985

Observations of the Geminga optical candidate

The present spectroscopy and photometry for the proposed optical counterpart of the X-ray source IE 0630 + 178, which is also a candidate for identification with the gamma-ray source 'Geminga', yields a spectrum that is featureless at the current S/N ratio and resists classification. The properties of the X-ray and optical objects, and the statistical circumstances of the identification process, do not support the association of optical, X-ray, and gamma-ray sources. The uniqueness of the X-ray source nevertheless suggests that its X-rays are thermal emission from the surface of a neutron star whose optical counterpart is an undetected blue star of B magnitude approximately 26.

Halpern, J. P.↗