YSOVAR: MID-INFRARED VARIABILITY AMONG YSOs IN THE STAR FORMATION REGION GGD12-15

Wolk, S. J.; Günther, H. M.; Poppenhaeger, Katja; Cody, Ann Marie; Rebull, L. M.; Forbrich, Jan; Gutermuth, Robert; Hillenbrand, Lynne A.; Plavchan, Peter; Stauffer, J. R.; Covey, Kevin R.; Song, Inseok

doi:10.1088/0004-6256/150/5/145

Cited by 22 publications

(34 citation statements)

References 73 publications

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“…Poppenhaeger et al (2015) find that color changes in the Spitzer bands of the YSOs in IRAS:250050+2720 are consistent with a mix of extinction and disk variability, with spots more prevalent among sources with heavily depleted dust emission. Wolk et al (2015) also find that extinction and disk emission changes are most consistent with the Spitzer variability in the cluster GGD 12-15. Near-infrared studies of …”

Section: Color Variationssupporting

confidence: 68%

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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: Color Variationssupporting

confidence: 68%

“…Previous studies have found year-to-year fluctuations (Parks et al 2014;Rebull et al 2014;Wolk et al 2015), suggesting that infrared variability is not limited to the timescales studied here. (Table 6), suggesting fluctuations on decade-long timescales.…”

Section: Very Long Timescale Variabilitysupporting

confidence: 55%

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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“…First, since young stars are known to be relatively bright X-ray sources, the X-ray data provide a sample of cluster members independent of their IR characteristics, and therefore the X-ray data allow us to include diskless YSOs in the study. Second, we can test suggestions that X-ray activity is related to IR variability: both Wolk et al (2015) and Poppenhaeger et al (2015) found a weak trend that X-ray-detected cluster members vary on longer timescales than members undetected in X-rays.…”

Section: Matching To Other Catalogsmentioning

confidence: 97%

“…They find almost all cluster members show significant variability, and the amplitude of the variability is larger in more embedded YSOs. Three additional papers in the series have examined IRAS 20050+2720, GGD12-15, and NGC 1333 Wolk et al 2015;Rebull et al 2015, respectively). The results among these clusters are fairly consistent: they find between 50% and 90% of the cluster members are variable, with the most embedded SEDs (class I and flat) being the most likely to be variable and showing the largest amplitude changes.…”

Section: Introductionmentioning

confidence: 99%

YSOVAR: Mid-infrared Variability among YSOs in the Star Formation Region Serpens South

Wolk

Günther

Poppenhaeger

et al. 2018

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We present a time-variability study of young stellar objects (YSOs) in the Serpens South cluster performed at 3.6 and 4.5 μm with the Spitzer Space Telescope; this study is part of the Young Stellar Object VARiability project. We have collected light curves for more than 1500 sources, including 85 cluster members, over 38 days. This includes 44 class I sources, 19 sources with flat spectral energy distributions (SEDs), 17 class II sources, and five diskless YSO candidates. We find a high variability fraction among embedded cluster members of ∼70%, whereas young stars without a detectable disk display no variability. We detect periodic variability for 32 sources with periods primarily in the range of 0.2-14 days and a subset of fast rotators thought to be field binaries. The timescale for brightness changes are shortest for stars with the most photospheric SEDs and longest for those with flat or rising SEDs. While most variable YSOs become redder when fainter, as would be expected from variable extinction, about 10% get bluer as they get fainter. One source, SSTYSV J183006.13−020108.0, exhibits "cyclical" color changes.

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“…Therefore, they are not used to model the SEDs. In the IRAC 3.6μm and 4.5μm bands, typically 0.2-0.4 mag variations are reported for low-mass YSOs (Faesi et al 2012;Wolk et al 2015). Moreover, Contreras et al (2016a) typically find lower-amplitude variability at these longer wavelengths compared to K-band variation.…”

Section: Sed Fittingmentioning

confidence: 96%

Highly Variable Young Massive Stars in Atlasgal Clumps

Kumar

Peña

Lucas

2016

ApJ

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High-amplitude variability in young stellar objects (YSOs) is usually associated with episodic accretion events. It has not been observed so far in massive YSOs. Here, the high-amplitude variable star sample of Contreras Peña et al. has been used to search for highly variable (ΔK 1 mag) sources coinciding with dense clumps mapped using the 850μm continuum emission by the ATLASGAL survey. A total of 18 variable sources are centered on the submillimeter clump peaks and coincide (<1″) with a 24μm point or compact (<10″) source. Of these 18 sources, 13 can be fit by YSO models. The 13 variable YSOs (VYSOs) have luminosities of ∼10 3 L e , an average mass of 8M e , and a range of ages up to 10 6 yr. A total of 11 of these 13 VYSOs are located in the midst of infrared dark clouds. Nine of the 13 sources have ΔK>2 mag, significantly higher compared to the mean variability of the entire VVV sample. The light curves of these objects sampled between 2010 and 2015 display rising, declining, or quasi-periodic behavior but no clear periodicity. Light-curve analysis using the Plavchan method shows that the most prominent phased signals have periods of a few hundred days. The nature and timescale of variations found in 6.7 Ghz methanol maser emission in massive stars are similar to that of the VYSO light curves. We argue that the origin of the observed variability is episodic accretion. We suggest that the timescale of a few hundred days may represent the frequency at which a spiraling disk feeds dense gas to the young massive star.

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YSOVAR: MID-INFRARED VARIABILITY AMONG YSOs IN THE STAR FORMATION REGION GGD12-15

Cited by 22 publications

References 73 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

YSOVAR: Mid-infrared Variability among YSOs in the Star Formation Region Serpens South

Highly Variable Young Massive Stars in Atlasgal Clumps

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