On the origin of the correlations between the accretion luminosity and emission line luminosities in pre-main-sequence stars

Mendigutía, I.; Oudmaijer, R. D.; Rigliaco, E.; Fairlamb, J.; Calvet, Nuria; Muzerolle, James; Cunningham, Nichol; Lumsden, S. L.

doi:10.1093/mnras/stv1540

Cited by 35 publications

(47 citation statements)

References 45 publications

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“…While this qualitatively matches our observed values, they derived a shallower slope than we obtained, although the two values are compatible. Finally, we note that the linear slope derived for the higher L and M subsample of objects is consistent with the almost linear relation between L acc and L observed in samples of Herbig Ae-Be stars (e.g., Mendigutía et al 2015), which have stellar masses higher than the objects studied here, but are also in general older. A possible interpretation for this bimodal distribution on thė M acc -M plane is a different evolutionary timescale for disk accretion around stars with different masses.…”

Section: Implications Of a Bimodal Distribution In The Relation Of Acsupporting

confidence: 89%

X-shooter study of accretion in Chamaeleon I

Manara

Testi

Herczeg

et al. 2017

A&A

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176

242

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The dependence of the mass accretion rate on the stellar properties is a key constraint for star formation and disk evolution studies. Here we present a study of a sample of stars in the Chamaeleon I star-forming region carried out using spectra taken with the ESO VLT/X-Shooter spectrograph. The sample is nearly complete down to stellar masses (M ) ∼ 0.1M for the young stars still harboring a disk in this region. We derive the stellar and accretion parameters using a self-consistent method to fit the broadband flux-calibrated medium resolution spectrum. The correlation between accretion luminosity to stellar luminosity, and of mass accretion rate to stellar mass in the logarithmic plane yields slopes of 1.9±0.1 and 2.3±0.3, respectively. These slopes and the accretion rates are consistent with previous results in various star-forming regions and with different theoretical frameworks. However, we find that a broken powerlaw fit, with a steeper slope for stellar luminosity lower than ∼ 0.45 L and for stellar masses lower than ∼ 0.3 M is slightly preferred according to different statistical tests, but the single power-law model is not excluded. The steeper relation for lower mass stars can be interpreted as a faster evolution in the past for accretion in disks around these objects, or as different accretion regimes in different stellar mass ranges. Finally, we find two regions on the mass accretion versus stellar mass plane that are empty of objects: one region at high mass accretion rates and low stellar masses, which is related to the steeper dependence of the two parameters we derived. The second region is located just above the observational limits imposed by chromospheric emission, at M ∼ 0.3 − 0.4M . These are typical masses where photoevaporation is known to be effective. The mass accretion rates of this region are ∼ 10 −10 M /yr, which is compatible with the value expected for photoevaporation to rapidly dissipate the inner disk.

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Section: Implications Of a Bimodal Distribution In The Relation Of Acsupporting

confidence: 89%

X-shooter study of accretion in Chamaeleon I

Manara

Testi

Herczeg

et al. 2017

A&A

Self Cite

176

242

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“…In contrast to the correlation with L O I , L acc shows no correlation with L * . Although such a correlation has been found in other samples, its absence here is probably because our sample covers a factor of ∼100 in L * while that of Mendigutía et al (2015) which includes brown dwarfs, spans eight orders of magnitude.…”

Section: Comparison To Recent Studies Of Luminosity Relationsmentioning

confidence: 47%

“…Additionally, a relation between L acc and L * was found by Mendigutía et al (2015) for a large sample of objects in various star-forming regions.…”

Section: Comparison To Recent Studies Of Luminosity Relationsmentioning

confidence: 93%

Tracing Slow Winds From T Tauri Stars via Low-Velocity Forbidden Line Emission

Simón¹,

Pascucci²,

Edwards³

et al. 2016

ApJ

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298

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Using Keck/HIRES spectra (Δ v∼7 km s −1 ) we analyze forbidden lines of [OI] 6300 Å, [OI] 5577 Åand [SII] 6731 Åfrom 33 T Tauri stars covering a range of disk evolutionary stages. After removing a high-velocity component (HVC) associated with microjets, we study the properties of the low-velocity component (LVC). The LVC can be attributed to slow disk winds that could be magnetically (magnetohydrodynamic) or thermally (photoevaporative) driven. Both of these winds play an important role in the evolution and dispersal of protoplanetary material. LVC emission is seen in all 30 stars with detected [OI] but only in two out of eight with detected [SII], so our analysis is largely based on the properties of the [OI] LVC. The LVC itself is resolved into broad (BC) and narrow (NC) kinematic components. Both components are found over a wide range of accretion rates and their luminosity is correlated with the accretion luminosity, but the NC is proportionately stronger than the BC in transition disks. The full width at half maximum of both the BC and NC correlates with disk inclination, consistent with Keplerian broadening from radii of 0.05 to 0.5 au and 0.5 to 5 au, respectively. The velocity centroids of the BC suggest formation in an MHD disk wind, with the largest blueshifts found in sources with closer to face-on orientations. The velocity centroids of the NC, however, show no dependence on disk inclination. The origin of this component is less clear and the evidence for photoevaporation is not conclusive.

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“…Specifically, if W 10% is indeed a good quantitative tracer of the accretion rate, fluctuations in W 10% would readily reveal fluctuations inṀacc. The latter is proportional to Lacc, itself correlated with the luminosity of accretion-driven emission (but see Mendigutía et al 2015) and thus we would expect W 10% to be correlated with LHα. While we have not measured that quantity, we note that the continuum brightness variability due to changes in veiling for most TTS are generally ≤50 per cent for non-outbursting TTS (e.g., Stauffer et al 2016), smaller than the amplitude of the line EW fluctuations for most of the accretors in our sample.…”

Section: Temporal Variability Of Individual Objectsmentioning

confidence: 86%

A search for passive protoplanetary discs in the Taurus–Auriga star-forming region

Duchêne

Becker

Yang

et al. 2017

Monthly Notices of the Royal Astronomical Society

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We conducted a 12-month monitoring campaign of 33 T Tauri stars (TTS) in Taurus. Our goal was to monitor objects that possess a disk but have a weak Hα line, a common accretion tracer for young stars, to determine whether they host a passive circumstellar disk. We used medium-resolution optical spectroscopy to assess the objects' accretion status and to measure the Hα line. We found no convincing example of passive disks; only transition disk and debris disk systems in our sample are non-accreting. Among accretors, we find no example of flickering accretion, leading to an upper limit of 2.2% on the duty cycle of accretion gaps assuming that all accreting TTS experience such events. Combining literature results with our observations, we find that the reliability of traditional Hα-based criteria to test for accretion is high but imperfect, particularly for low-mass TTS. We find a significant correlation between stellar mass and the full width at 10 per cent of the peak (W 10% ) of the Hα line that does not seem to be related to variations in free-fall velocity. Finally, our data reveal a positive correlation between the Hα equivalent width and its W 10% , indicative of a systematic modulation in the line profile whereby the high-velocity wings of the line are proportionally more enhanced than its core when the line luminosity increases. We argue that this supports the hypothesis that the mass accretion rate on the central star is correlated with the Hα W 10% through a common physical mechanism.

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On the origin of the correlations between the accretion luminosity and emission line luminosities in pre-main-sequence stars

Cited by 35 publications

References 45 publications

X-shooter study of accretion in Chamaeleon I

X-shooter study of accretion in Chamaeleon I

Tracing Slow Winds From T Tauri Stars via Low-Velocity Forbidden Line Emission

A search for passive protoplanetary discs in the Taurus–Auriga star-forming region

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