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The mass of the neutron star in Vela X-1
We measured the radial-velocity curve of HD 77581, the B-supergiant companion of the X-ray pulsar Vela X-1, using 183 high-resolution optical spectra obtained in a nine-month campaign. We derive
Evidence for a Massive Neutron Star from a Radial-velocity Study of the Companion to the Black-widow Pulsar PSR B1957+20
The most massive neutron stars constrain the behavior of ultra-dense matter, with larger masses possible only for increasingly stiff equations of state. Here, we present evidence that the black-widow
The Spectrum of the Brown Dwarf Gliese 229B
We present a spectrum of the cool K) brown dwarf Gliese 229B. This spectrum, with a (T eff \ 900 relatively high signal-to-noise ratio per spectral resolution element spans the wavelength range
The Variable Radio-to-X-Ray Spectrum of the Magnetar XTE J1810–197
We have observed the 5.54 s anomalous X-ray pulsar XTE J1810-197 at radio, millimeter, and infrared (IR) wavelengths, with the aim of learning about its broadband spectrum. At the IRAM 30 m
The Masses of the Millisecond Pulsar J1012+5307 and Its White Dwarf Companion
We report on spectroscopy of the white dwarf companion of the millisecond radio pulsar PSR J1012+5307. We find strong Balmer absorption lines, as would be expected for a cool DA white dwarf. The
Determination of the mass of the neutron star in SMC X-1, LMC X-4, and Cen X-3 with VLT/UVES
We present the results of a spectroscopic monitoring campaign of the OB-star companions to the eclipsing X-ray pulsars SMC X−1, LMC X−4 and Cen X−3. High-resolution optical spectra obtained with UVES
The masses of PSR J1911-5958A and its white dwarf companion
We present spectroscopic and photometric observations of the optical counterpart to PSR J1911−5958A, a millisecond pulsar located towards the globular cluster NGC6752. We measure radial velocities
An optical counterpart to the anomalous X-ray pulsar 4U0142+61
Deep optical observations of the field around 4U0142+61, which is the brightest AXP in X-rays, are reported, and an object with peculiar optical colours at the position of the X-ray source is found, and it is argued that it is the optical counterpart.
In the last few years, over 43 millisecond radio pulsars have been discovered by targeted searches of unidentified γ-ray sources found by the Fermi Gamma-Ray Space Telescope. A large fraction of
Infrared helium emission lines from Cygnus X-3 suggesting a Wolf-Rayet star companion
CYGNUS X-3 is one of the most luminous X-ray sources in the Galaxy1,2, a bright infrared source3 and a radio source that undergoes huge outbursts4. The system is a binary, presumably a neutron star