Ysovar: Mid-Infrared Variability in the Star-Forming Region Lynds 1688

Günther, H. M.; Cody, Ann Marie; Covey, Kevin R.; Hillenbrand, Lynne A.; Plavchan, Peter; Poppenhaeger, Katja; Rebull, L. M.; Stauffer, J. R.; Wolk, S. J.; Allen, Lori; Bayo, A.; Gutermuth, Robert; Hora, J. L.; Meng, Huan; Morales-Calderón, M.; Parks, J. R.; Song, Inseok

doi:10.1088/0004-6256/148/6/122

Cited by 48 publications

(74 citation statements)

References 105 publications

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“…The number of observations given in column two is not the same for all sources in a field due to edge effects or artifacts in the image unrelated to deriving accurate positional information. The last column notes comparisons to previous variability studies by Alves de Oliveira & Casali (2008), Parks et al (2014), and Günther et al (2014). We note that the most extensive of these was by Parks et al, who utilized nearly daily observations over a 2.5 year period from the 2MASS survey (Cutri et al 2003).…”

Section: Confirmed and Possible New Variablesmentioning

confidence: 88%

Relative Proper Motions in the Rho Ophiuchi Cluster

Wilking

Vrba

Sullivan

2015

ApJ

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Near-infrared images optimized for astrometry have been obtained for four fields in the high-density L 1688 cloud core over a 12 year period. The targeted regions include deeply embedded young stellar objects (YSOs) and very low luminosity objects too faint and/or heavily veiled for spectroscopy. Relative proper motions in R.A. and decl. were computed for 111 sources and again for a subset of 65 YSOs, resulting in a mean proper motion of (0,0) for each field. Assuming each field has the same mean proper motion, YSOs in the four fields were combined to yield estimates of the velocity dispersions in R.A. and decl. that are consistent with 1.0 km s −1 . These values appear to be independent of the evolutionary state of the YSOs. The observed velocity dispersions are consistent with the dispersion in radial velocity derived for optically visible YSOs at the periphery of the cloud core and are consistent with virial equilibrium. The higher velocity dispersion of the YSOs in the plane of the sky relative to that of dense cores may be a consequence of stellar encounters due to dense cores and filaments fragmenting to form small groups of stars or the global collapse of the L 1688 cloud core. An analysis of the differential magnitudes of objects over the 12 year baseline has not only confirmed the near-infrared variability for 29 YSOs established by prior studies, but has also identified 18 new variability candidates. Four of these have not been previously identified as YSOs and may be newly identified cluster members.

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Section: Confirmed and Possible New Variablesmentioning

confidence: 88%

Relative Proper Motions in the Rho Ophiuchi Cluster

Wilking

Vrba

Sullivan

2015

ApJ

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“…In addition, the disk is detected at 70 µm with Herschel/PACS . It was listed as a long timescale near-infrared variable by Parks et al (2014), while Günther et al (2014) detected ∼20% variations in the mid-infrared with Spitzer.…”

Section: Appendixmentioning

confidence: 99%

A Continuum of Accretion Burst Behavior in Young Stars Observed by K2

Cody

Hillenbrand

David

et al. 2017

ApJ

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We present 29 likely members of the young ρ Oph or Upper Sco regions of recent star formation that exhibit "accretion burst" type light curves in K2 time series photometry. The bursters were identified by visual examination of their ∼80 day light curves, though all satisfy the M < −0.25 flux asymmetry criterion for burst behavior defined by Cody et al. (2014). The burst sources represent ≈9% of cluster members with strong infrared excess indicative of circumstellar material. Higher amplitude burster behavior is correlated with larger inner disk infrared excesses, as inferred from WISE W 1 − W 2 color. The burst sources are also outliers in their large Hα emission equivalent widths. No distinction between bursters and non-bursters is seen in stellar properties such as multiplicity or spectral type. The frequency of bursters is similar between the younger, more compact ρ Oph region, and the older, more dispersed Upper Sco region. The bursts exhibit a range of shapes, amplitudes (∼10-700%), durations (∼1-10 days), repeat time scales (∼3-80 days), and duty cycles (∼10-100%). Our results provide important input to models of magnetospheric accretion, in particular by elucidating the properties of accretion-related variability in the low state between major longer duration events such as EX Lup and FU Ori type accretion outbursts. We demonstrate the broad continuum of accretion burst behavior in young stars -extending the phenomenon to lower amplitudes and shorter timescales than traditionally considered in the theory of pre-main sequence accretion history.

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“…p CHXR 37: 0 079 (13 au) binary (Lafrenière et al 2008 Table 3). In particular, the YSOVAR survey, with its Spitzer observations of IRAS:20050 +2720 , NGC 1333 (Rebull et al 2015), the ONC (Morales-Calderón et al 2011), L1688 (Günther et al 2014), and GGD 12-15 , finds that 60%-85% of YSOs with an infrared excess are variable. Studies of IC 348 , NGC 2264 , and the Orion molecular cloud (Megeath et al 2012) have found similar results.…”

Section: Finding Variable Starsmentioning

confidence: 99%

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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Ysovar: Mid-Infrared Variability in the Star-Forming Region Lynds 1688

Cited by 48 publications

References 105 publications

Relative Proper Motions in the Rho Ophiuchi Cluster

Relative Proper Motions in the Rho Ophiuchi Cluster

A Continuum of Accretion Burst Behavior in Young Stars Observed by K2

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

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