The Mass Dependence Between Protoplanetary Disks and Their Stellar Hosts

Abstract

We present a substantial extension of the millimeter (mm) wave continuum photometry catalog for circumstellar dust disks in the Taurus star-forming region, based on a new "snapshot" λ = 1.3 mm survey with the Submillimeter Array. Combining these new data with measurements in the literature, we construct a mm-wave luminosity distribution, f (L mm ), for Class II disks that is statistically complete for stellar hosts with spectral types earlier than M8.5 and has a 3σ depth of roughly 3 mJy. The resulting census eliminates a longstanding selection bias against disks with late-type hosts, and thereby demonstrates that there is a strong correlation between L mm and the host spectral type. By translating the locations of individual stars in the Hertzsprung-Russell diagram into masses and ages, and adopting a simple conversion between L mm and the disk mass, M d , we confirm that this correlation corresponds to a statistically robust relationship between the masses of dust disks and the stars that host them. A Bayesian regression technique is used to characterize these relationships in the presence of measurement errors, data censoring, and significant intrinsic scatter: the best-fit results indicate a typical 1.3 mm flux density of ∼25 mJy for 1 M hosts and a power-law scaling L mm ∝ M 1.5−2.0 * . We suggest that a reasonable treatment of dust temperature in the conversion from L mm to M d favors an inherently linear M d ∝ M * scaling, with a typical disk-to-star mass ratio of ∼0.2%-0.6%. The measured rms dispersion around this regression curve is ±0.7 dex, suggesting that the combined effects of diverse evolutionary states, dust opacities, and temperatures in these disks imprint a full width at half-maximum range of a factor of ∼40 on the inferred M d (or L mm ) at any given host mass. We argue that this relationship between M d and M * likely represents the origin of the inferred correlation between giant planet frequency and host star mass in the exoplanet population, and provides some basic support for the core accretion model for planet formation. Moreover, we caution that the effects of incompleteness and selection bias must be considered in comparative studies of disk evolution, and illustrate that fact with statistical comparisons of f (L mm ) between the Taurus catalog presented here and incomplete subsamples in the Ophiuchus, IC 348, and Upper Sco young clusters.

Resolved Co Gas Interior to the Dust Rings of the Hd 141569 Disk

“…where F ν is the flux density, d is the distance, κ ν is the mass opacity, and B ν (T d ) is the Planck function evaluated at a dust temperature of T d (e.g., Andrews et al 2013). This flux is only sensitive to the small dust grains; in a system with collisionally generated dust grains a substantial amount of mass is locked in meter to km-sized planetesimals that do not emit efficiently at these wavelengths and any mass inferred from the radio emission underestimates the total mass.…”

Disk Masses for Embedded Class I Protostars in the Taurus Molecular Cloud

“…Over the past few decades, there have been numerous studies of nearby star-forming regions at millimeter wavelengths with the aim of measuring disk masses for large samples of disks, and this work has been accelerated in recent years by the power of ALMA to quickly survey large numbers of sources (e.g., Beckwith et al 1990;Osterloh & Beckwith 1995;Dutrey et al 1996;Andrews & Williams 2005, 2007Eisner et al 2008Eisner et al , 2016Mann & Williams 2010;Andrews et al 2013;Mann et al 2014;Ansdell et al 2016Ansdell et al , 2017Barenfeld et al 2016;Pascucci et al 2016). These surveys have tended to target the population of Class II protostar disks because they are no longer embedded in an envelope, and so estimates of their disk masses are more straightforward.…”

“…It has also been shown that Class II disk masses are correlated with stellar mass (Andrews et al 2013, Ansdell et al 2016Barenfeld et al 2016;Pascucci et al 2016). As such, when comparing disk mass distributions, we must take care to ensure that our samples have similar stellar host properties; otherwise, our disk mass measurements may be biased.…”

“…Thus, the disk mass distributions among Class I and II sources appear different, with a significance of >2σ. Finally, we follow the procedure outlined in Andrews et al (2013) to compare the distributions. First, we randomly draw 10 disks from the Class II sample.…”

Gaia's potential for the discovery of circumbinary planets

“…This means it will explore a wider mass range than the radial-velocity and transit techniques. In addition, the binary nature of the host can become a big help as well: Protoplanetary disc masses scale with the central mass, be it a single or binary star (Andrews et al 2013), and heavier discs are expected to produce more gas giants (Mordasini et al 2012). A G dwarf + G dwarf binary, for instance, had a disc mass equivalent to a single A star.…”