The SB9 catalogue: status, comparison with non-single stars from Gaia DR3 and evolution to SBX

Abstract

The Ninth Catalogue of Spectroscopic Binary Orbits (SB9) is a comprehensive compilation of spectroscopic binaries (SBs) with orbital parameters sourced from literature, comprising approximately 4000 systems (2800 single-lined and 1200 double-lined). This work presents the latest status of SB9 after two decades of development, detailing the statistical properties of SBs through orbital period distributions and eccentricity-period diagrams categorized by spectral type and evolutionary stage. We performed a rigorous cross-match with Gaia Data Release 3 (DR3) to update astrometric parameters and compare SB9 with the Gaia DR3 Non-Single Star (NSS) catalogue. Our methodology utilized positional separations, magnitudes, and proper-motion back-propagation for identification. The final SB9 version updated by D. Pourbaix includes 4003 systems, including higher-order multiples: 152 triples, 71 quadruples, and 14 higher-order systems. Of these, 3976 have Gaia DR3 identifiers; 21 are too bright and six too faint for detection. Ten SB9 systems with periods exceeding 1180 days were spatially resolved by Gaia DR3. We identified a common sample of 827 binaries cross-matched with Gaia NSS, with 655 considered highly reliable based on period and eccentricity differences under 10%. The limited overlap (20-30% of SB9) results from NSS selection cuts, brightness limits, and temporal baselines. This study highlights the complementary strengths of both catalogues and establishes a benchmark sample for binary star research. Finally, this work marks the transition of SB9 into SBX (The eXtended Catalogue of Spectroscopic Binary Orbits), featuring a modern relational database, improved web interface, and Virtual Observatory access standards to enhance data quality and accessibility for the stellar community.

Figures (22)

• Figure 1: Distribution of the S$_{\mathrm{B}^9}$ binaries per spectral type and luminosity class for primaries (left) and secondaries (right). There are 16% of primaries without spectral type (grey in the left panel) and only 9% of secondaries with a spectral type (non-grey in the right panel).
• Figure 2: Distribution of the orbital periods of the SB1, SB2 and combination of them. The distribution shows three peaks at 0.6, 7 and 1800 d which are discussed in the text. Error bars are taken as Poissonian. The dotted line represents the mode of the log-normal distribution of binaries 2017ApJS..230...15M peaking around 270 a. SBs lie on the short-period side of this distribution.
• Figure 3: Distribution of the orbital periods per spectral type for dwarfs (left) and giants (right) of SB primary components. The $y$-axis corresponds to the period distribution normalised so that the integral of the frequency times the bin size equals unity. Colour codes the spectral types. In the left panel, vertical lines correspond to the minimum period for a given spectral-type from contact equal-mass binaries.
• Figure 4: The $e - \log{P}$ diagram of the S$_{\mathrm{B}^9}$ binaries colour-coded by spectral type for dwarfs (left) and for giants (right panel). The solid line is the empirical fit to the S$_{\mathrm{B}^9}$ data 2004AA...424..727P.
• Figure 5: Left: one-to-one cross-match for the S$_{\mathrm{B}^9}$ system 307 ($\beta$ Ori B, $G=6.6$). $\beta$ Ori A is too bright to be observed by Gaia. The S$_{\mathrm{B}^9}$ system 307 was wrongly assigned the coordinates of $\beta$ Ori A (in S$_{\mathrm{B}^9}$) explaining such a large separation in the match. This example illustrates the need to have a large cone search radius value of 10 arcsec. Middle: zoom on many-to-one matches for the S$_{\mathrm{B}^9}$ systems 2682 and 3927 separated by 0.14 arcsec, not resolvable by Gaia. For readability, the radius in the plot has been decreased to 0.5 arcsec. The grey cross corresponds to the Gaia source at epoch J2016.0. Right: one-to-many and many-to-many cross-matches for the S$_{\mathrm{B}^9}$ system 3319 (TIC 139154020, $G=15.7$), member of the open cluster NGC 6819. This cross-match involves two other S$_{\mathrm{B}^9}$ systems and three Gaia DR3 sources leading to six one-to-many and three many-to-many matches.