The binary of the pulsar PSR B1259−63 and the Be star LS 2883 has been observed at the 2010 and 2014 periastron passages in the near-infrared (NIR) bands using the IRSF/SIRIUS and SIRPOL. The light curves in the J-, H-, and Ks-bands are almost identical in these periastron passages. A flare starts no later than 10 days before periastron and the maximum brightening of about 0.1 mag is observed 12–17 days after periastron. The rising part of the light curve is steeper and reaches a peak slightly earlier in the Ks-band than in the other bands, thus a characteristic track appears on the NIR color–magnitude diagram. The time lag between the NIR light curves indicates that the variation in the Be circumstellar disk first occurs in an outer region. We propose that the initial rapid contraction followed by the gradual expansion of the disk is evoked by the rapidly changing tidal torque around periastron and the resultant change of the optically thick area causes the observed NIR light curves.

中文翻译：

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伽马射线双星 PSR B1259−63 / LS 2883 近星光通道周围的近红外增亮

脉冲星 PSR B1259-63 和 Be 星 LS 2883 的联星已使用 IRSF/SIRIUS 和 SIRPOL 在 2010 年和 2014 年的近红外 (NIR) 波段中观察到。在这些近星体通道中，J、H 和 Ks 波段的光变曲线几乎相同。耀斑不迟于近星点前 10 天开始，在近星点后 12-17 天观察到约 0.1 等的最大亮度。光变曲线的上升部分更陡峭，在 Ks 波段比其他波段稍早达到峰值，因此 NIR 色幅图上出现了特征轨迹。近红外光曲线之间的时间滞后表明，Be 环星盘的变化首先发生在外部区域。