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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-widowExpand
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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 deriveExpand
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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 mExpand
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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 rangeExpand
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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. TheExpand
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A Multiplicity Census of Young Stars in Chamaeleon I
We present the results of a multiplicity survey of 126 stars spanning ~0.1-3 solar masses in the ~2-Myr-old Chamaeleon I star-forming region, based on adaptive optics imaging with the ESO Very LargeExpand
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The Astropy Project: Building an Open-science Project and Status of the v2.0 Core Package
The Astropy Project supports and fosters the development of open-source and openly developed Python packages that provide commonly needed functionality to the astronomical community. A key element ofExpand
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Direct Imaging and Spectroscopy of a Planetary-Mass Candidate Companion to a Young Solar Analog
We present Gemini near-infrared adaptive optics imaging and spectroscopy of a planetary-mass candidate companion to 1RXS J160929.1–210524, a roughly solar-mass member of the 5 Myr old Upper ScorpiusExpand
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An optical counterpart to the anomalous X-ray pulsar 4U0142+61
The energy source of the anomalous X-ray pulsars (AXPs) is not understood, hence their designation as anomalous. Unlike binary X-ray pulsars, no companions are seen, so the energy cannot be suppliedExpand
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Lithium Depletion of Nearby Young Stellar Associations
We estimate cluster ages from lithium depletion in five pre-main-sequence groups found within 100 pc of the Sun: the TW Hydrae association, η Chamaeleontis cluster, β Pictoris moving group,Expand
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