Early Evolution of Stellar Groups and Clusters: Environmental Effects on Forming Planetary Systems

By Fred C. Adams, E. Proszkow, M. Fatuzzo, P. Myers. 2005

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This paper studies the dynamical evolution of young groups/clusters, with N = 100-1000 members, from their embedded stage out to ages of ~10 Myr. We use N-body simulations to explore how their evolution depends on the system size N and the initial conditions. Motivated by recent observations suggesting that stellar groups begin their evolution with subvirial speeds, this study compares subvirial starting states with virial starting states. Multiple realizations of equivalent cases (100 simulations per initial condition) are used to build up a robust statistical description of these systems, e.g., the probability distribution of closest approaches, the mass profiles, and the probability distribution for the radial location of cluster members. These results provide a framework from which to assess the effects of groups/clusters on the processes of star and planet formation and to study cluster evolution. The distributions of radial positions are used in conjunction with the probability distributions of the expected far-ultraviolet (FUV) luminosities (calculated here as a function of cluster size N) to determine the radiation exposure of circumstellar disks. The distributions of closest approaches are used in conjunction with scattering cross sections (calculated here as a function of stellar mass using ~105 Monte Carlo scattering experiments) to determine the probability of disruption for newly formed solar systems. We use the nearby cluster NGC 1333 as a test case in this investigation. The main conclusion of this study is that clusters in this size range have only a modest effect on forming planetary systems. The interaction rates are low, so that the typical solar system experiences a single encounter with closest approach distance b ~ 1000 AU. The radiation exposure is also low, with median FUV flux G0 ~ 900 (1.4 ergs s-1 cm-2), so that photoevaporation of circumstellar disks is only important beyond 30 AU. Given the low interaction rates and modest radiation levels, we suggest that solar system disruption is a rare event in these clusters.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/366e6a9514c784fe408514b04ea3876115478c24

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Citations in the corpus

FILAMENTARY STRUCTURE OF STAR-FORMING COMPLEXES (2009, methodology): “Related definitions of young stellar groups or clusters are given by Lada & Lada (2003), Porras et al (2003), Adams et al (2006), Jørgensen et al (2008), and Gutermuth et al (2008a).”
A SPITZER SURVEY OF YOUNG STELLAR CLUSTERS WITHIN ONE KILOPARSEC OF THE SUN: CLUSTER CORE EXTRACTION AND BASIC STRUCTURAL ANALYSIS (2009, result): “We have provided an example in Figure 10, the number of YSOs versus the effective radius, a common analysis published in some recent survey papers (Adams et al. 2006; Allen et al. 2007).”
A CORRELATION BETWEEN SURFACE DENSITIES OF YOUNG STELLAR OBJECTS AND GAS IN EIGHT NEARBY MOLECULAR CLOUDS (2011, background): “…between the cores and the surrounding, moderate density gas is small relative to the velocity dispersion inferred from the observed linewidth and the observed velocity gradients in the bulk gas motions (e.g. Walsh et al. 2004, 2007; Adams et al. 2006; Kirk et al. 2007; Jørgensen et al. 2008).”
THE LONG-TERM EVOLUTION OF THE GALACTIC DISK TRACED BY DISSOLVING STAR CLUSTERS (2010, background): “Partly-embedded clusters detected in nearby star-forming regions using 2MASS and Spitzer/IRAC have surface densities of a few 0.01 g cm−2 (Adams et al. 2006; Allen et al. 2007), but because these samples are selected in the near-infrared they are strongly biased against more deeply-embedded and…”
DYNAMICAL MASS SEGREGATION ON A VERY SHORT TIMESCALE (2009, background): “Proszkow et al. (2009) also find that the Orion star forming region shows signatures of subvirial dynamics on scales of about 10 pc (see also Adams et al. 2006).”
The planet nine hypothesis (2019, background): “…to separately calculate the cross sections for fly-by encounters to ionize the solar system, and combine these results with the rate of stellar encounters to determine an optical depth, τs, for scattering (Adams and Laughlin, 2001; Li and Adams, 2015; Adams et al., 2006; Proszkow and Adams, 2009).”
The effects of fly‐bys on planetary systems (2010, background): “The rate at which this occurs in embedded clusters was studied by Adams et al. (2004, 2006).”
The initial conditions of star formation in the Ophiuchus main cloud: Kinematics of the protocluster condensations , (2007, background): “This suggests that protoclusters often start their evolution from “cold”, out-ofequilibrium initial conditions (cf. Adams et al. 2006), possibly as a result of the influence of external triggers (cf. Nutter eal.”
Gravitational Instabilities in Circumstellar Disks (2016, background): “Many lines of argument, from measures of cloud angular momentum (Goodman et al. 1993), to stellar interactions (Adams et al. 2006), to direct observations in both absorption (Eisner et al. 2008) and millimeter wavelengths (Andrews et al. 2011) suggest that 102 − 103AU are reasonable limits for disk…”
The Birth Environment of the Solar System (2010, methodology): “With these subvirial starting conditions, the initial orbits are directed more radially inward (compared with virial starting states) and some dynamical memory of this initial condition is retained (Adams et al. 2006).”
Embedded star clusters and the formation of the Oort Cloud (2006, methodology): “After our simulations were completed, we became aware of the work of Adams et al. (2006), who found similar results concerning binaries.”
Global Models for the Evolution of Embedded, Accreting Protostellar Disks (2007, background): “Similarly, as the disk edge extends towards other, potentially more luminous stars, the actual flux received will increase, heating the disk above the ∼ 10K temperature that we routinely find (Adams et al. 2006).”