The Recurrent Eclipse of an Unusual Pre-Main-Sequence Star in IC 348

Abstract

The recurrence of a previously documented eclipse of a solar-like pre-mainsequence star in the young cluster IC 348 has been observed. The recurrence interval is 4.7 ± 0.1 yr and portions of 4 cycles have now been seen. The duration of each eclipse is at least 3.5 years, or ∼ 75% of a cycle, verifying that this is not an eclipse by a stellar companion. The light curve is generally symmetric and approximately flat-bottomed. Brightness at maximum and minimum have been rather stable over the years but the light curve is not perfectly repetitive or smooth and small variations exist at all phases. We confirm that the star is redder when fainter. Models are discussed and it is proposed that this could be a system similar to KH 15D in NGC 2264. Specifically, it may be an eccentric binary in which a portion of the orbit of one member is currently occulted during some binary phases by a circumbinary disk. The star deserves sustained observational attention for what it may reveal about the circumstellar environment of low-mass stars of planet-forming age.

Short-period variability in the Class II methanol maser source G12.89+0.49 (IRAS 18089−1732)

“…Another group reported recurrent eclipses of a low mass pre‐main‐sequence star in the young cluster IC348 with a 4.7 yr period (Nordhagen et al 2006). The eclipse lasted for 3.5 yr (75 per cent) of the cycle.…”

The unusual pre-main-sequence star V718 Persei (HMW 15)

“…The fact that the spectral types assigned to the object cover a rather large range, G8 -K6 (Herbig 1998;Luhman et al 1998), and may even change with wavelength, could flag the presence of two stellar spectra. As pointed out by Nordhagen et al (2006), a variable radial velocity with an amplitude of several km s −1 should then be detectable from high-resolution spectroscopy.…”

“…(Barsunova et al 2005). More detailed observations by Nordhagen et al (2006) show that V718 Per undergoes recurrent, 3.5 year long eclipses with a period of P = 4.7 ± 0.1 years (see also Grinin et al 2006a). Thus, given the very long eclipse duration and its comparitively short period, this system is one of the most exotic eclipsing systems known.…”

“…Since a 4.7 year period suggests orbital motion as the underlying cause, most working hypotheses propose that the eclipses are produced by an extended body, Article published by EDP Sciences like an irregular or warped circumstellar or circumbinary disk seen nearly edge-on (Cohen et al 2004;Nordhagen et al 2006;Grinin et al 2006a). A still unresolved question is whether or not V718 Per is a close binary, similar to KH 15D, where the orbital displacement of the stars would periodically hide one or both components behind a shared circumbinary disk.…”

Long-term photometry of IC 348 with the Young Exoplanet Transit Initiative network

“…This period grid had a range from P min = 0.04 d (∼ 1 h) to P max = T/3 = 293 d (where T is our observational timebase). We used such a wide range because at least one long-periodic eclipse is known in IC 348 (Nordhagen et al 2006b) and more might be discovered. We chose our lower limit to include short-term variability but not stellar pulsations.…”