The identification of 93 day periodic photometric variability for YSO YLW 16A

Plavchan, Peter; Güth, Tina; Laohakunakorn, Nadanai; Parks, J. R.

doi:10.1051/0004-6361/201220747

Cited by 25 publications

(23 citation statements)

References 54 publications

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“…Wider binaries can experience periodic dimming as components of the binary pass behind a circumbinary disk, as is the case in KH 15D (e.g., Windemuth & Herbst 2014;Arulanantham et al 2016). The 131-day-period WL 4 system and the 93-day-period YLW 16A system (Plavchan et al 2013) show similar dimming behavior, suggesting a similar origin for their variability. A companion misaligned with the disk can also drag material out of the midplane (Fragner & Nelson 2010), leading to periodic occultations of the primary star.…”

Section: Discussionmentioning

confidence: 85%

Spitzer Observations of Long-Term Infrared Variability Among Young Stellar Objects in Chamaeleon I

Flaherty

DeMarchi

Muzerolle

et al. 2016

ApJ

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Infrared variability is common among young stellar objects, with surveys finding daily to weekly fluctuations of a few tenths of a magnitude. Space-based observations can produce highly sampled infrared light curves, but are often limited to total baselines of about 1 month due to the orientation of the spacecraft. Here we present observations of the Chameleon I cluster, whose low declination makes it observable by the Spitzer Space Telescope over a 200-day period. We observe 30 young stellar objects with a daily cadence to better sample variability on timescales of months. We find that such variability is common, occurring in ∼80% of the detected cluster members. The change in [3.6]-[4.5] color over 200 days for many of the sources falls between that expected for extinction and fluctuations in disk emission. With our high cadence and long baseline we can derive power spectral density curves covering two orders of magnitude in frequency and find significant power at low frequencies, up to the boundaries of our 200-day survey. Such long timescales are difficult to explain with variations driven by the interaction between the disk and stellar magnetic field, which has a dynamical timescale of days to weeks. The most likely explanation is either structural or temperature fluctuations spread throughout the inner ∼0.5 au of the disk, suggesting that the intrinsic dust structure is highly dynamic.

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Section: Discussionmentioning

confidence: 85%

Spitzer Observations of Long-Term Infrared Variability Among Young Stellar Objects in Chamaeleon I

Flaherty

DeMarchi

Muzerolle

et al. 2016

ApJ

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“…Companions are also invoked in several examples of presumed disk-eclipsing young stars that, like PTF 10nvg, have long periods. Specifically, KH15D at 48 days (Hamilton et al 2012), WL4 at 131 days (Plavchan et al 2008), and YLW16A at 92 days (Plavchan et al 2010) have extinction-like flux dips between a few tenths and several magnitudes in depth. Several of these stars have companions in the 25-50 AU region that are hypothesized to induce warps in the disks.…”

Section: Constraints On Multiplicitymentioning

confidence: 98%

“…Other well-known low-amplitude young star variables such as UX Ori, RR Tau, VV Ser, AA Tau as well as the "dippers" discussed by Morales-Calderón et al (2011) and Cody & Hillenbrand (2010, 2011) also appear to be undergoing short timescale extinction events. Larger amplitude and-importantly-longperiod examples include KH15D (Hamilton et al 2012), WL4 (Plavchan et al 2008), and YLW16A (Plavchan et al 2010), which have found explanation in binary interactions with circumstellar disk material.…”

Section: Introductionmentioning

confidence: 99%

HIGHLY VARIABLE EXTINCTION AND ACCRETION IN THE JET-DRIVING CLASS I-TYPE YOUNG STAR PTF 10nvg (V2492 Cyg, IRAS 20496+4354)

Hillenbrand

Miller

Covey

et al. 2013

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We report extensive new photometry and spectroscopy of the highly variable young stellar object PTF 10nvg (also known as IRAS 20496+4354 and V2492 Cyg), including optical and near-infrared time-series data as well as mid-infrared and millimeter data. Following the previously reported 2010 rise to R PTF 13 m . 5 and subsequent fade, during 2011 and 2012 the source underwent additional episodes of brightening, followed by several magnitude dimming events including prolonged faint states at R PTF 20 m . The observed high-amplitude variations are largely consistent with extinction changes (ΔA V up to 30 mag) having a ∼220 day quasi-periodic signal. However, photometry measured when the source was near maximum brightness in mid-2010 as well as in late-2012 does not phase well to this period. Spectral evolution includes not only changes in the spectral slope but also correlated variation in the prominence of TiO/VO/CO bands and atomic line emission, as well as anti-correlated variation in forbidden line emission which, along with H 2 , dominates optical and infrared spectra at faint epochs. Notably, nightto-night variations in several forbidden doublet strengths and ratios are observed. High-dispersion spectra were obtained in a variety of photometric states and reveal time-variable line profiles. Neutral and singly ionized atomic species are likely formed in an accretion flow and/or impact while the origin of zero-velocity atomic Li i λ6707 in emission is unknown. Forbidden lines, including several rare species, exhibit blueshifted emission profiles and likely arise from an outflow/jet. Several of these lines are also seen spatially offset from the continuum source position, presumably in a shocked region of an extended jet. Blueshifted absorption components of the Na i D doublet, K i λλ7665, 7669 doublet, and the O i 7774 triplet, as well as blueshifted absorption components seen against the broad Hα and Ca ii triplet emission lines, similarly are formed in the outflow. CARMA maps resolve on larger scales a spatially extended outflow in millimeter-wavelength CO. We attribute the recently observed photometric and spectroscopic behavior to rotating circumstellar disk material located at separation a ≈ 0.7(M * /M ) 1/3 AU from the continuum source, causing the semi-periodic dimming. Occultation of the central star as well as the bright inner disk and the accretion/outflow zones renders shocked gas in the inner part of the jet amenable to observation at the faint epochs. We discuss PTF 10nvg as a source exhibiting both accretion-driven (perhaps analogous to V1647 Ori) and extinction-driven (perhaps analogous to UX Ori or GM Cep) high-amplitude variability phenomena.

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“…Although thousands of PMS stars have been photometrically monitored in the past years, only few objects show a variable behaviour that resembles KH 15D, i.e. YLW 16A and WL 4 in ρ Oph (Plavchan et al 2010(Plavchan et al , 2008, and V718 Per in IC 348 (Grinin et al 2008). In the case of WL 4 and YLW 16A, the authors proposed the existence of a new class of periodic disc-eclipsing binaries to explain the KH 15D type variability, in which a third body in these systems is responsible for the warping of the inner circumbinary disc needed to produce the eclipses, while Grinin et al (2008) argued that V718 Per is most probably a single star surrounded by an edge-on circumstellar disc with an irregular mass distribution at the inner edge of the disc, which causes the observed periodic variability.…”

Section: Introductionmentioning

confidence: 99%

An unusual very low-mass high-amplitude pre-main sequence periodic variable

Rodríguez-Ledesma

Mundt

Ibrahimov

et al. 2012

A&A

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Aims. We have investigated the nature of the variability of CHS 7797, an unusual periodic variable in the Orion Nebula Cluster.Methods. An extensive I-band photometric data set of CHS 7797 was compiled between 2004−2010 using various telescopes. Further optical data have been collected in R and z bands. In addition, simultaneous observations of the ONC region including CHS 7797 were performed in the I, J, K s & IRAC 3.6 and 4.5 μm bands over a time interval of ≈40 d. Results. CHS 7797 shows an unusual large-amplitude variation of ≈1.7 mag in the R, I, and z bands with a period 17.786 ± 0.03 d (FAP = 1 × 10 −15 %). The amplitude of the brightness modulation decreases only slightly at longer wavelengths. The star is faint during ≈2/3 of the period and the shape of the phased light-curves for the seven different observing seasons shows minor changes and small-amplitude variations. Interestingly, there are no significant colour-flux correlations for λ < ∼ 2 μm, while the object becomes redder when fainter at longer wavelengths. CHS 7797 has a spectral type of M 6 and an estimated mass between 0.04−0.1 M . Conclusions. The analysis of the data suggests that the periodic variability of CHS 7797 is most probably caused by an orbital motion. Variability as a result of rotational brightness modulation by a hot spot is excluded by the lack of any colour-brightness correlation in the optical. The latter indicates that CHS 7797 is most probably occulted by circumstellar matter in which grains have grown from typical 0.1 μm to ≈1−2 μm sizes. We discuss two possible scenarios in which CHS 7797 is periodically eclipsed by structures in a disc, namely that CHS 7797 is a single object with a circumstellar disc, or that CHS 7797 is a binary system, similar to KH 15D, in which an inclined circumbinary disc is responsible of the variability. Possible reasons for the typical 0.3 mag variations in I-band at a given phase are discussed.

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The identification of 93 day periodic photometric variability for YSO YLW 16A

Cited by 25 publications

References 54 publications

Spitzer Observations of Long-Term Infrared Variability Among Young Stellar Objects in Chamaeleon I

Spitzer Observations of Long-Term Infrared Variability Among Young Stellar Objects in Chamaeleon I

HIGHLY VARIABLE EXTINCTION AND ACCRETION IN THE JET-DRIVING CLASS I-TYPE YOUNG STAR PTF 10nvg (V2492 Cyg, IRAS 20496+4354)

An unusual very low-mass high-amplitude pre-main sequence periodic variable

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