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PSR,J1723$-$2837 is a redback millisecond pulsar (MSP) with a low-mass companion in a 14.8,h orbit. The systems properties closely resemble those of transitional MSPs that alternate between spin-down and accretion-powered states. In this paper we report on long-term photometry of the 15.5,mag companion to the pulsar. We use our data to illustrate that the star experiences sporadic activity, which we attribute to starspots. We also find that the companion is not tidally locked and infer $P_{rm s}/P_{rm b}= 0.9974(7)$ for the ratio between the rotational and orbital periods. Finally, we place constraints on various parameters, including the irradiation efficiency and pulsar mass. We discuss similarities with other redback MSPs and conclude that starspots may provide the most likely explanation for the often seen irregular and asymmetric optical lightcurves.
PSR J2129-0429 is a redback eclipsing millisecond pulsar binary with an unusually long 15.2 hour orbit. It was discovered by the Green Bank Telescope in a targeted search of unidentified Fermi gamma-ray sources. The pulsar companion is optically brig
Low-mass white dwarfs (LMWDs) are believed to be exclusive products of binary evolution, as the Universe is not yet old enough to produce them from single stars. Because of the strong tidal forces operating during the binary interaction phase, the re
We have used deep V and R images acquired at the ESO Very Large Telescope to identify the optical companion to the binary pulsar PSR J0610-2100, one of the black-widow millisecond pulsars recently detected by the Fermi Gamma-ray Telescope in the Gala
We present the first optical spectroscopy of five confirmed (or strong candidate) redback millisecond pulsar binaries, obtaining complete radial velocity curves for each companion star. The properties of these millisecond pulsar binaries with low-mas
We report on radio timing and multiwavelength observations of the 4.66 ms redback pulsar J1048+2339, which was discovered in an Arecibo search targeting the Fermi-LAT source 3FGLJ1048.6+2338. Two years of timing allowed us to derive precise astrometr