The Initial Mass Function and the Occurrence of Stars of Small Mass

Warner, Brian D.

doi:10.1086/127725

Cited by 11 publications

(4 citation statements)

References 3 publications

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“…Using an observed luminosity function for nearby stars, Salpeter (1955) found that the stellar mass distribution (or IMF) seemed to obey a power-law relation, ξ(m) ∝ m −1.35 for 0.4 M ⊙ M 10 M ⊙ . Here, ξ(m) is defined as dN = ξ(m)d log m, where dN is the number of stars of mass m lying between m and m + dm (Warner 1961). Thus,…”

Section: Relation To the Imfmentioning

confidence: 99%

The Mass Distribution of Starless and Protostellar Cores in Gould Belt Clouds

Sadavoy

Francesco

Bontemps

et al. 2010

ApJ

105

164

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Using data from the SCUBA Legacy Catalogue (850 µm) and Spitzer Space Telescope (3.6 -70 µm), we explore dense cores in the Ophiuchus, Taurus, Perseus, Serpens, and Orion molecular clouds. We develop a new method to discriminate submillimeter cores found by SCUBA as starless or protostellar, using point source photometry from Spitzer wide field surveys. First, we identify infrared sources with red colors associated with embedded young stellar objects (YSOs). Second, we compare the positions of these YSO-candidates to our submillimeter cores. With these identifications, we construct new, self-consistent starless and protostellar core mass functions (CMFs) for the five clouds. We find best fit slopes to the high-mass end of the CMFs of −1.26 ± 0.20, −1.22 ± 0.06, −0.95 ± 0.20, and −1.67 ± 0.72 for Ophiuchus, Taurus, Perseus, and Orion, respectively. Broadly, these slopes are each consistent with the −1.35 power-law slope of the Salpeter initial mass function (IMF) at higher masses, but suggest some differences. We examine a variety of trends between these CMF shapes and their parent cloud properties, potentially finding a correlation between the high-mass slope and core temperature. We also find a trend between core mass and effective size, but we are very limited by sensitivity. We make similar comparisons between core mass and size with visual extinction (for A V ≥ 3) and find no obvious trends. We also predict the numbers and mass distributions of cores that future surveys with SCUBA-2 may detect in each of these clouds.

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Section: Relation To the Imfmentioning

confidence: 99%

The Mass Distribution of Starless and Protostellar Cores in Gould Belt Clouds

Sadavoy

Francesco

Bontemps

et al. 2010

ApJ

105

164

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“…In the case of random pairing (RP), the primary and companion mass are both independently drawn from f M (M), and swapped, if necessary, so that the most massive star is the primary. As a result of this swapping, neither the resulting primary mass distribution f M 1 (M 1 ), nor the companion mass distribution f M 2 (M 2 ), nor the system mass distribution f M T (M T ) is equal to the generating mass distribution f M (M); see, e,g., Warner (1961); Tout (1991);Mal'Kov & Zinnecker (2001). On the other hand, the mass distribution of all stars f all (M), i.e., all singles, primaries and companions, is equal to f M (M).…”

Section: Pairing Function Rp (Random Pairing)mentioning

confidence: 99%

Exploring the consequences of pairing algorithms for binary stars

Kouwenhoven

Goodwin

Zwart³

et al. 2008

A&A

102

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Knowledge of the binary population in stellar groupings provides important information about the outcome of the star forming process in different environments. Binarity is also a key ingredient in stellar population studies, and is a prerequisite for calibrating the binary evolution channels. In this paper we present an overview of several commonly used methods of pairing individual stars into binary systems, which we refer to as pairing functions. These pairing functions are frequently used by observers and computational astronomers, either for their mathematical convenience or because they roughly describe the expected outcome of the star forming process. We discuss the consequences of each pairing function for interpreting observations and numerical simulations. The binary fraction and mass ratio distribution generally depend strongly on the selection of the range in primary spectral type in a sample. The mass ratio distribution and binary fraction derived from a binarity survey among a mass-limited sample of targets is thus not representative of the population as a whole. Neither theory nor observations indicate that random pairing of binary components from the mass distribution, the simplest pairing function, is realistic. It is more likely that companion stars are formed in a disc around a star or that a pre-binary core fragments into two binary components. The results of our analysis are important for (i) the interpretation of the observed mass ratio distribution and binary fraction for a sample of stars; (ii) a range of possible initial condition algorithms for star cluster simulations; and (iii) how to distinguish between the different star formation scenarios.

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“…Such algorithm or pairing function is known as random pairing (RP). While RP produces very steeply decreasing ( ) ∼ − 2 distribution when a restricted subset of massive stars is considered (Warner 1961), the overall distribution is actually growing as the sample is dominated by lowmass stars (Piskunov & Malkov 1991).…”

Section: Imf and Pairing Functionsmentioning

confidence: 99%

Pairing function of visual binary stars

Chulkov¹

2020

Monthly Notices of the Royal Astronomical Society

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An all-sky sample of 1227 visual binaries based on Washington Double Star catalogue is constructed to infer the IMF, mass ratio, and projected distance distribution with a dedicated population synthesis model. Parallaxes from Gaia DR2 and Hipparcos are used to verify the distance distribution. The model is validated on the single-star Tycho-2 sample and successfully reproduces the observed magnitudes and angular separations. The projected separation distribution follows f(s) ∼ s−1.2 in 102 − 2 · 103 AU range for 1–4.5 m⊙ primary stars. Several algorithms are explored as pairing functions. Random pairing is confidently rejected. Primary-constrained (PCP) and split-core pairing (SCP), the scenarios adopting primary component’s or total system’s mass as fundamental, are considered. The preferred IMF slope is α ∼ 2.8 either way. A simple power-law mass ratio distribution is unlikely, but the introduction of a twin excess provides a favourable result. PCP with f(q) ∼ q−1 is preferred with a tiny twin fraction, models with f(q) ∼ q−1.5 are acceptable when a larger twin excess is allowed. SCP is similar to PCP when a larger slope of the power law is adopted: f(q) ∼ qβ + 0.7.

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The Initial Mass Function and the Occurrence of Stars of Small Mass

Cited by 11 publications

References 3 publications

The Mass Distribution of Starless and Protostellar Cores in Gould Belt Clouds

The Mass Distribution of Starless and Protostellar Cores in Gould Belt Clouds

Exploring the consequences of pairing algorithms for binary stars

Pairing function of visual binary stars

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