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Project Progress

In this reporting period, we requested a Swift Target-of-Opportunity (ToO) observation to monitor long-term X-ray variations of the protostar V1647 Ori that currently experiences strong mass accretion. The observation was approved and performed in 2015 January. We also set up coordinated optical/near-infrared (IR) observations of the star with ground-based observatories.

We triggered a Target-of-Opportunity (ToO) observation of the erupting protostar V1647 Ori with the Swift observatory to monitor its recent X-ray activity. The X-ray observations of this star in 2010 and 2013, performed with the XMM-Newton and Swift X-ray observatories, detected a drop in the X-ray flux by an order of magnitude from observations taken earlier in the eruption. The new Swift observation was performed in 2015 January, and was coordinated with optical observations at Kitt Peak and the Japanese observatory network. During this observation, the protostar showed a low X-ray flux similar to the observations in 2010 and 2013, confirming the end of the X-ray eruption. The optical/near-infrared fluxes remained high (i.e., at the level of the eruption), suggesting that the mass accretion activity still continued. Since the optical/near-infrared emission is a direct indicator of the mass accretion activity, an mechanism other than mass accretion must play a role in the X-ray production.