Accretion Rates in Herbig Ae stars

By R. G. Lopez, A. Natta, L. Testi, É. Habart. 2006

215 citations recorded by the source corpus.

Aims. Accretion rates from disks around pre-main sequence stars are of importance for our understanding of planetary formation and disk evolution. We provide in this paper estimates of the mass accretion rates in the disks around a large sample of Herbig Ae stars. Methods. We obtained medium resolution 2 μm spectra and used the results to compute values of M acc from the measured luminosity of the Br γ emission line, using a well established correlation between L(Br γ ) and the accretion luminosity L acc . Results. We find that 80% of the stars, all of which have evidence of an associated circumstellar disk, are accreting matter, with rates 3 x 10 -9 ≤ M acc ≤ 10 -6 M ⊙ /yr; for 7 objects, 6 of which are located on the ZAMS in the HR diagram, we do not detect any line emission. Few HAe stars (25%) have M acc > 10 -7 M ⊙ /yr. Conclusions. In most HAe stars the accretion rate is sufficiently low that the gas in the inner disk, inside the dust evaporation radius, is optically thin and does not prevent the formation of a puffed-up rim, where dust is directly exposed to the stellar radiation. When compared to the M acc values found for lower-mass stars in the star forming regions Taurus and Ophiuchus, HAe stars have on average higher accretion rates than solar-mass stars; however, there is a lack of very strong accretors among them, probably due to the fact that they are on average older.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/320dc40e864761318d0b16d3d8f9447d9e0168a2

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In Astronomy and Astrophysics

1. D. Wilner
2. Jonathan P. Williams
3. S. Andrews
4. L. Testi
5. C. Dullemond
6. L. Cieza
7. G. Herczeg
8. Ralf Klessen

Citations in the corpus

• Protoplanetary Disks and Their Evolution (2011, background): “The higher accretion rates and radiation environment are likely to be responsible for the shorter disk lifetimes in higher mass stars (Calvet et al. 2005, Garcia Lopez et al. 2006, Hillenbrand 2008).”
• SHADOWS CAST BY A WARP IN THE HD 142527 PROTOPLANETARY DISK (2014, background): “A ∼ 10−7 M yr−1 stellar accretion rate (Garcia Lopez et al. 2006) would quickly deplete the inner disk, whose dust mass is estimated at ∼ 10−9 M (Verhoeff et al. 2011).”
• Protoplanetary disk lifetimes vs stellar mass and possible implications for giant planet populations (2015, background): “Stronger radiation fields and higher accretion rates of high-mass stars (Calvet et al. 2005; Garcia Lopez et al. 2006; Hillenbrand 2008) are likely to affect the evolution of protoplanetary disks even during A52, page 7 of 13 A&A 576, A52 (2015) Pr ot op la ne ta ry d is k fr ac tio n (% ) 35-40%…”
• Accretion-driven turbulence as universal process: galaxies, molecular clouds, and protostellar disks (2009, methodology): “To connect to real measurements, we overplot the data presented by Lopez et al. (2006).”
• Millimeter imaging of HD 163296: probing the disk structure and kinematics (2007, background): “This is very likely a good approximation, given the relatively low accretion rate measured in HD 163296 (∼ 10−7 M⊙/yr; Garcia Lopez et al., 2006).”
• STRUCTURES IN THE PROTOPLANETARY DISK OF HD142527 SEEN IN POLARIZED SCATTERED LIGHT (2013, background): “While photoevaporation can explain holes up to ∼20 AU in accreting and even larger holes for non-accreting disks (Owen et al. 2011), it cannot explain the gap in HD142527, which has an accretion rate of 6.9 × 10−8 M yr−1 (Garcia Lopez et al. 2006) and a very large hole.”
• Star and Protoplanetary Disk Properties in Orion's Suburbs (2009, background): “Power law fits of the formṀacc∝Mα∗ have yielded values in the range 1.0−2.1 for the exponentα (White & Basri 2003; Muzerolle et al. 2003; Calvet et al. 2004; Muzerolle et al. 2005; Mohanty et al. 2005; Natta et al. 2006; Garcia Lopez et al. 2006; Herczeg & Hillenbrand 2008; Gatti et al. 2008).”
• Accretion disks in luminous young stellar objects (2015, background): “Systematic studies determining Ṁacc in the disks of HAeBe stars have so far used either the Brγ line (Garcia Lopez et al., 2006, with a sample restricted to A-type stars) or the Balmer continuum excess (Donehew & Brittain, 2011; Mendigutı́a et al., 2011; Fairlamb et al., 2015).”
• Spectroastrometric Imaging of Molecular Gas within Protoplanetary Disk Gaps (2008, background): “…both show varying degrees of accretion at relatively low rates (5 × 10−10 to 5 × 10−9M⊙ yr −1), inferring the presence of some gas very close to the central stars (< 0.1 AU) (Muzerolle et al. 2000; Garcia Lopez et al. 2006), this does not trace the distribution of gas in the disk at larger radii.”
• Accretion onto Pre-Main-Sequence Stars (2016, background): “Use of near-IR lines in particular minimizes the effect of uncertainties in extinction corrections (e.g., Muzerolle et al. 1998, Calvet 2004, Natta et al. 2006, Salyk et al. 2013, Rigliaco et al. 2015); mitigates confusion with Balmer line absorption in the photospheres of HAeBe stars (e.g., Garcı́a”