Additional Periodic Variables in NGC 2264

Kearns, K. E.; Herbst, W.

doi:10.1086/300426

Cited by 83 publications

(93 citation statements)

References 5 publications

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“…Periodic variation of AA Tau is marked in green. Long-term extinction events of the faders KH 15D, RW Aur, V409 Tau, and DM Ori from Kearns & Herbst (1998) and Rodriguez et al (2015Rodriguez et al ( , 2016b are shown by triangles and plotted with "timescale" indicating the duration of the event. These extinction events are usually deeper, though this may be an observational bias.…”

Section: The Extinction Curve Of the Dips Of Gi Taumentioning

confidence: 99%

Star–Disk Interactions in Multiband Photometric Monitoring of the Classical T Tauri Star GI Tau

Guo

Herczeg

Jose

et al. 2018

ApJ

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The variability of young stellar objects is mostly driven by star-disk interactions. In long-term photometric monitoring of the accreting T Tauri star GI Tau, we detect extinction events with typical depths of DṼ 2.5 mag that last for days to months and often appear to occur stochastically. In 2014-2015, extinctions that repeated with a quasi-period of 21 days over several months are the first empirical evidence of slow warps predicted by magnetohydrodynamic simulations to form at a few stellar radii away from the central star. The reddening is consistent with =  R 3.85 0.5 V and, along with an absence of diffuse interstellar bands, indicates that some dust processing has occurred in the disk. The 2015-2016 multiband light curve includes variations in spot coverage, extinction, and accretion, each of which results in different traces in color-magnitude diagrams. This light curve is initially dominated by a month-long extinction event and a return to the unocculted brightness. The subsequent light curve then features spot modulation with a 7.03 day period, punctuated by brief, randomly spaced extinction events. The accretion rate measured from U-band photometry ranges from´-1.3 10 8 to´-1.1 10 10 M e yr −1 (excluding the highest and lowest 5% of high-and low-accretion rate outliers), with an average of4.7 -10 9 M e yr −1 . A total of 50% of the mass is accreted during bursts of >´-12.8 10 9 M e yr -1, which indicates limitations on analyses of disk evolution using single-epoch accretion rates.

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Section: The Extinction Curve Of the Dips Of Gi Taumentioning

confidence: 99%

Star–Disk Interactions in Multiband Photometric Monitoring of the Classical T Tauri Star GI Tau

Guo

Herczeg

Jose

et al. 2018

ApJ

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“…While its dramatic brightness change alone makes the star an important object to monitor photometrically, our interest in it was piqued by recent results on a possibly analogous object, KH 15D (Kearns et al 1997;Kearns & Herbst 1998;Hamilton et al 2001;Herbst et al 2002b). It has been reported that this K-type pre-main-sequence star in NGC 2264 undergoes a periodic eclipse with a depth of $3.5 mag every 48.36 days.…”

Section: Introductionmentioning

confidence: 99%

Periodic Variability in the Pre-Main-Sequence Object CB 34V

2003

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A photometric study of the G-type pre-main-sequence star CB 34V was undertaken at Van Vleck Observatory during the 2001-2002 observing season. The star remained in its bright state throughout the 5 month monitoring period, showing no evidence of the large amplitude variability that originally drew attention to it. However, it did exhibit periodic variability with an amplitude of $0.6 mag. A highly significant peak is present in the periodogram at 1.186 days, but analysis of the light curve suggests that the actual rotation period of the star is twice that-2.372 days. Apparently, the star had similar spots on opposite hemispheres during this time and we view it close to equator-on. This circumstance allows us to place additional constraints on the radius and luminosity of the star. The new data argue against its being an FU Orionis star and in favor of its being either a UX Orionis star or an object (similar to KH 15D) that is eclipsed episodically by circumstellar matter.

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“…On the PMS, photometric monitoring programs for the determination of rotation periods were mainly focused on the ONC where a multiplicity of rotation periods were measured (Attridge & Herbst 1992;Herbst et al 2001Herbst et al , 2002Rebull 2001;Stassun et al 1999). In addition, a few rotation periods are available for stars in the Taurus Auriga Cloud (Bouvier et al 1993), IC 348 (Herbst et al 2000), and NGC 2264 (Kearns & Herbst 1998;Kearns et al 1997). However, a statistically significant set of known periods exists only for the ONC.…”

Section: Introductionmentioning

confidence: 99%

Rotational evolution of low mass stars: The case of NGC 2264

Lamm¹,

Mundt²,

Bailer‐Jones³

et al. 2005

A&A

115

218

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Abstract. Our study is based on an extensive photometric monitoring program in the young (2-4 Myr) open cluster NGC 2264 by Lamm et al. (2004a). This program resulted in a sample of 405 periodic variables which are most likely pre-main sequence (PMS) members of the cluster. The periodic variability of these stars results from the rotational modulation of the light by stellar spots. In this paper we investigate the rotation period evolution of young stars. This is done by comparing the period distribution of the older NGC 2264 with that of the younger Orion Nebular Cluster (ONC, age: ∼1 Myr) which is known from the literature. The age ratio between the two clusters was estimated on the basis of PMS models to be about 2 +0.75 −0.5 . We find that the period distribution of NGC 2264 is similar in form to the ONC but shifted to shorter periods. In both clusters the period distribution depends strongly on the mass and it is bimodal for higher mass stars with M > ∼ 0.25 M while it is unimodal for lower mass stars with M < ∼ 0.25 M . In addition the lower mass stars rotate much faster on average than the higher mass stars. Quantitative comparison between the period distributions of both clusters suggests that a large fraction (about 80%) of stars have spun up from the age of the ONC to the age of NGC 2264. Based on this estimate and the estimated age ratio between the two clusters we find that the average spin up by a factor of 1.5−1.8 from the age of the ONC to the age of NGC 2264 is consistent with a decreasing stellar radius and conservation of angular momentum, for most stars. However, within NGC 2264 we did not find any significant spin up from the younger to older stars in the cluster. We also found indications for some ongoing disk-locking in NGC 2264, in particular for the higher mass stars. Our analysis of the period distribution suggests that about 30% of the higher mass stars in NGC 2264 could be magnetically locked into co-rotation with their inner disk. In the case of the lower mass stars, disk-locking seems to be less important for the rotational evolution of the stars. This interpretation is supported by the analysis of the stars' Hα emission. This analysis indicates that the locking period of the higher mass stars is about P = 8 days. For the lower mass stars this analysis indicates a locking period of about 2-3 days. We argue that the latter stars are probably not "completely" locked to their disk and propose an evolution scenario for these stars which we call "moderate angular momentum loss". In this scenario angular momentum is continuously removed from the stars but at a rate too low to lock the stars with a constant rotation period. We have done a detailed comparison with the recently published rotational period study of NGC 2264 of Makidon et al. (2004). Even though their obtained period distribution of their quality 1 data on NGC 2264 is indistinguishable within the statistical errors from ours, we come to quite different conclusions about the interpretation. One major reason for these discrepanci...

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Additional Periodic Variables in NGC 2264

Cited by 83 publications

References 5 publications

Star–Disk Interactions in Multiband Photometric Monitoring of the Classical T Tauri Star GI Tau

Star–Disk Interactions in Multiband Photometric Monitoring of the Classical T Tauri Star GI Tau

Periodic Variability in the Pre-Main-Sequence Object CB 34V

Rotational evolution of low mass stars: The case of NGC 2264

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