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Pulsed accretion in a variable protostar



Periodic increases in luminosity arising from variable accretion rates have been predicted for some pre-main-sequence close binary stars as they grow from circumbinary disks1,2,3. The phenomenon is known as pulsed accretion and can affect the orbital evolution and mass distribution of young binaries2,4, as well as the potential for planet formation5,6. Accretion variability is a common feature of young stars, with a large range of amplitudes and timescales as measured from multi-epoch observations at optical7,8 and infrared9,10,11,12,13 wavelengths. Periodic variations consistent with pulsed accretion have been seen in only a few young binaries via optical accretion tracers14,15,16, albeit intermittently with accretion luminosity variations ranging from zero to 50 per cent from orbit to orbit. Here we report that the infrared luminosity of a young protostar (of age about 105 years) increases by a factor of ten in roughly one week every 25.34 days. We attribute this to pulsed accretion associated with an unseen binary companion. The strength and regularity of this accretion signal is surprising; it may be related to the very young age of the system, which is a factor of ten younger than the other pulsed accretors previously studied.

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Figure 1: Multi-epoch spectral energy distribution of L54361.
Figure 2: Photometric light curves for L54361.
Figure 3: Near-infrared images of L54361.
Figure 4: Protostellar spectral energy distribution models for L54361.


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This work was supported in part by NASA through Spitzer and HST GO contracts. We thank S. Lubow, M. Livio and N. Calvet for discussions. E.F. was visiting the Infrared Processing and Analysis Center, Caltech, during the course of this work.

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Authors and Affiliations



J.M. and K.F. designed the Spitzer observations. Z.B. and R.G. reduced the IRAC images and compiled the photometry, while J.M. reduced and analysed the MIPS data. J.M. and E.F. extracted and analysed the IRS spectroscopy. J.M. designed the HST observations and analysed the images. E.F. calculated the radiative transfer models and fitted the observed SEDs. All authors contributed to the writing of the paper.

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Correspondence to James Muzerolle.

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The authors declare no competing financial interests.

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Muzerolle, J., Furlan, E., Flaherty, K. et al. Pulsed accretion in a variable protostar. Nature 493, 378–380 (2013).

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