Time-monitoring observations of the ro-vibrational overtone CO bands in young stars

Eisner, J. A.; Rieke, G. H.; Rieke, M. J.; Flaherty, Kevin; Arnold, Timothy; Stone, Jordan; Cortes, S. R.; Cox, Erin G.; Hawkins, Clint; Cole, Austin; Zajac, S.; Rudolph, Alexander

doi:10.1093/mnras/stt1029

Cited by 2 publications

(4 citation statements)

References 41 publications

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“…CO emission has been observed previously for both of these (e.g., Carr 1989;Biscaya et al 1997;Prato et al 2003). The line-to-continuum ratio observed here for V1331 Cyg is comparable to that seen in previous observations, including ones with similar resolution to the KI data (Biscaya et al 1997;Eisner et al 2013). The line-to-continuum ratio of AS 353 A in our KI and NIRSPEC data is somewhat higher than seen in previous observations (Carr 1989;Prato et al 2003), although there does seem to be some variability in the CO emission strength (Biscaya et al 1997).…”

Section: Spectra and Spatial Distributions Of Co Overtone Emissionsupporting

confidence: 91%

“…However calibration artifacts (e.g., due to mismatches between observed and template spectra for late-type calibrators) may be responsible for the apparent features. Recent CO overtone spectra of these sources show no features in AS 442 or MWC 275, but possible evidence for weak CO emission in V1685 Cyg (Eisner et al 2013). Strong features seen in the V 2 and differential phase data for V1685 Cyg (Figures 8 and 9) strengthen the case for real CO emission in this source.…”

Section: V1685mentioning

confidence: 73%

“…The CO overtone bandheads are made up of numerous lines tracing rovibrational transitions with ∆v = 2. Overtone transitions are rare compared to the occurrence rate of Brγ emission, but are found toward a number of young stars (Carr 1989;Najita et al 1996aNajita et al , 2000Najita et al , 2007Najita et al , 2009Biscaya et al 1997;Thi et al 2005;Brittain et al 2007;Berthoud et al 2007;Berthoud 2008;Eisner et al 2013). …”

Section: Introductionmentioning

confidence: 99%

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Constraining the sub-au-scale distribution of hydrogen and carbon monoxide gas around young stars with the Keck Interferometer

Eisner

Hillenbrand

Stone

2014

Monthly Notices of the Royal Astronomical Society

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We present Keck Interferometer observations of T Tauri and Herbig Ae/Be stars with a spatial resolution of a few milliarcseconds and a spectral resolution of ∼ 2000. Our observations span the K-band, and include the Brγ transition of Hydrogen and the v = 2 → 0 and v = 3 → 1 transitions of carbon monoxide. For several targets we also present data from Keck/NIRSPEC that provide higher spectral resolution, but a seeing-limited spatial resolution, of the same spectral features. We analyze the Brγ emission in the context of both disk and infall/outflow models, and conclude that the Brγ emission traces gas at very small stellocentric radii, consistent with the magnetospheric scale. However some Brγ-emitting gas also seems to be located at radii of 0.1 AU, perhaps tracing the inner regions of magnetically launched outflows. CO emission is detected from several objects, and we generate disk models that reproduce both the KI and NIRSPEC data well. We infer the CO spatial distribution to be coincident with the distribution of continuum emission in most cases. Furthermore the Brγ emission in these objects is roughly coincident with both the CO and continuum emission. We present potential explanations for the spatial coincidence of continuum, Brγ, and CO overtone emission, and explore the implications for the low occurrence rate of CO overtone emission in young stars. Finally, we provide additional discussion of V1685 Cyg, which is unusual among our sample in showing large differences in emitting region size and spatial position as a function of wavelength.

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Section: Spectra and Spatial Distributions Of Co Overtone Emissionsupporting

confidence: 91%

Section: V1685mentioning

confidence: 73%

Section: Introductionmentioning

confidence: 99%

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Constraining the sub-au-scale distribution of hydrogen and carbon monoxide gas around young stars with the Keck Interferometer

Eisner

Hillenbrand

Stone

2014

Monthly Notices of the Royal Astronomical Society

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“…We developed an IDL-based data reduction pipeline to produce calibrated spectra (described in detail in Eisner et al 2013). The pipeline works on an entire night of data as a block, producing telluric-corrected, wavelength-calibrated spectra for each object observed during the night.…”

Section: Observations and Data Reductionmentioning

confidence: 99%

Time-monitoring observations of Brγ emission from young stars

Eisner

Rieke

et al. 2014

Monthly Notices of the Royal Astronomical Society

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We present multiple epochs of near-IR spectroscopy for a sample of 25 young stars, including T Tauri, Herbig Ae/Be, and FU Ori objects. Using the FSPEC instrument on the Bok 90-inch telescope, we obtained K-band spectra of the Brγ transition of hydrogen, with a resolution of ≈ 3500. Epochs were taken over a span of >1 year, sampling time-spacings of roughly one day, one month, and one year. The majority of our targets show Brγ emission, and in some cases these are the first published detections. Time-variability is seen in approximately half of the targets showing Brγ emission. We compare the observed variability with expectations for rotationally-modulated accretion onto the central stars and time-variable continuum emission or extinction from matter in the inner disk. Our observations are not entirely consistent with models of rotationally-modulated magnetospheric accretion. Further monitoring, over a larger number of epochs, will facilitate more quantitative constraints on variability timescales and amplitudes, and a more conclusive comparison with theoretical models.

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Time-monitoring observations of the ro-vibrational overtone CO bands in young stars

Cited by 2 publications

References 41 publications

Constraining the sub-au-scale distribution of hydrogen and carbon monoxide gas around young stars with the Keck Interferometer

Constraining the sub-au-scale distribution of hydrogen and carbon monoxide gas around young stars with the Keck Interferometer

Time-monitoring observations of Brγ emission from young stars

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