Raghavan et al. (2010)

Abstract (paraphrased)¶

A comprehensive assessment of companions to a volume-limited sample of 454 solar-type (F6–K3) stars within 25 pc, drawn from Hipparcos and combining long-baseline and speckle interferometry, proper-motion companions, radial-velocity monitoring, and literature data. The observed fractions of single : double : triple : higher-order systems are 56 : 33 : 8 : 3 % (54 : 34 : 9 : 3 % counting confirmed companions), implying the majority (54%) of solar-type stars are single — in contrast to earlier estimates. The orbital-period distribution is unimodal and roughly log-normal with a median of about 300 years; the period–eccentricity relation shows the expected circularization for $P < 12$ d followed by a roughly flat eccentricity distribution; the mass-ratio distribution favours near-equal pairs. This is the modern update to Duquennoy & Mayor (1991).

Verified facts (abstract, Table 1, §2)¶

• Volume-limited field census, 454 solar-type primaries within 25 pc — characterizes multiplicity vs colour ($B-V$, i.e. primary mass), period, mass ratio, and eccentricity, not a spatial / radial binary-fraction profile.

• Period distribution: log-normal, median ~300 yr ($\log_{10}(P/\mathrm{d}) \approx 5.0$), $\sigma_{\log P} \approx 2.28$ — broader and longer-period than DM91’s 180 yr / $\mu=4.8$.

• Eccentricity: circularized below $P \approx 12$ d, then a roughly flat distribution for wider pairs (differs from DM91’s tendency toward thermal $f(e)=2e$ at the widest separations).

Use in progenax¶

• progenax.binaries.LogNormalPeriod — the docstring notes Raghavan (2010) as the modern revision of the DM91 defaults ($\mu_{\log P}=4.8$, $\sigma=2.3$). See Duquennoy & Mayor (1991).

• progenax.binaries.RadialBinaryFraction — cited (with Sana 2012, Moe & Di Stefano 2017) only to motivate that the binary fraction varies with primary mass / environment. Raghavan is a field census and provides no radial $f_b(r)$ law; the implemented form is phenomenological.

Notes¶

Raghavan et al. (2010) supersedes DM91 as the most complete solar-type multiplicity census, but progenax keeps the DM91 period defaults for continuity (both are documented). The eccentricity difference (DM91 wide-thermal vs Raghavan flat) reflects sample and bias differences and is noted where the eccentricity samplers cite their provenance.