paired: A Statistical Framework for Determining Stellar Binarity with Gaia RVs. I. Planet Hosting Binaries

Chance, Quadry; Foreman-Mackey, Daniel; Ballard, Sarah; Casey, Andrew R.; Price-Whelan, Adrian M.

doi:10.48550/arxiv.2206.11275

Cited by 4 publications

(3 citation statements)

References 45 publications

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“…These velocities are consistent within uncertainties. The velocity scatter from multiple Gaia RVS transits is large but typical for stars of similar spectral type, distance, and signal-tonoise ratio (Chance et al 2022), and there is no evidence for excess astrometric scatter (Penoyre et al 2020).…”

Section: A6 Binarity and Photometric Variabilitymentioning

confidence: 97%

Spectacular Nucleosynthesis from Early Massive Stars

Ji,

Curtis,

Storm

et al. 2024

ApJL

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Stars that formed with an initial mass of over 50 M ⊙ are very rare today, but they are thought to be more common in the early Universe. The fates of those early, metal-poor, massive stars are highly uncertain. Most are expected to directly collapse to black holes, while some may explode as a result of rotationally powered engines or the pair-creation instability. We present the chemical abundances of J0931+0038, a nearby low-mass star identified in early follow-up of the SDSS-V Milky Way Mapper, which preserves the signature of unusual nucleosynthesis from a massive star in the early Universe. J0931+0038 has a relatively high metallicity ([Fe/H] = −1.76 ± 0.13) but an extreme odd–even abundance pattern, with some of the lowest known abundance ratios of [N/Fe], [Na/Fe], [K/Fe], [Sc/Fe], and [Ba/Fe]. The implication is that a majority of its metals originated in a single extremely metal-poor nucleosynthetic source. An extensive search through nucleosynthesis predictions finds a clear preference for progenitors with initial mass >50 M ⊙, making J0931+0038 one of the first observational constraints on nucleosynthesis in this mass range. However, the full abundance pattern is not matched by any models in the literature. J0931+0038 thus presents a challenge for the next generation of nucleosynthesis models and motivates the study of high-mass progenitor stars impacted by convection, rotation, jets, and/or binary companions. Though rare, more examples of unusual early nucleosynthesis in metal-poor stars should be found in upcoming large spectroscopic surveys.

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Section: A6 Binarity and Photometric Variabilitymentioning

confidence: 97%

Spectacular Nucleosynthesis from Early Massive Stars

Ji,

Curtis,

Storm

et al. 2024

ApJL

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“…To search for more direct evidence of stellar multiplicity, we used paired, a statistical framework that uses Gaia radial velocity error measurements to search for binarity (Chance et al 2022), which typically detects binaries at separations of up to a few astronomical unit and mass ratios above 0.1. Stellar multiplicity can be detected in the Gaia radial velocity measurements as the presence of excess noise, compared to stars of similar apparent magnitude and color.…”

Section: Evidence Of Binarity With Pairedmentioning

confidence: 99%

Many Roads Lead to Lithium: Formation Pathways For Lithium-rich Red Giants

Sayeed,

Ness,

Montet

et al. 2024

ApJ

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Stellar models predict that lithium (Li) inside a star is destroyed during the first dredge-up phase, yet 1.2% of red giant stars are Li-rich. We aim to uncover possible origins of this population, by analyzing 1099 Li-rich giants (A(Li) ≥ 1.5) in GALAH DR3. To expose peculiar traits of Li-rich stars, we construct a reference sample of Li-normal (doppelgänger) stars with matched evolutionary state and fiducial iron-peak and alpha-process abundances ([Fe/H] and [Mg/Fe]). Comparing Li-rich and doppelgänger spectra reveals systematic differences in the Hα and Ca-triplet line profiles associated with the velocity broadening measurement. We also find twice as many Li-rich stars appear to be fast rotators (2% with v broad ≳ 20 km s−1) compared to doppelgängers. On average, Li-rich stars have higher abundances than their doppelgängers, for a subset of elements, and Li-rich stars at the base of RGB have higher mean s-process abundances (≥0.05 dex for Ba, Y, Zr), relative to their doppelgängers. External mass-transfer from intermediate-mass AGB companions could explain this signature. Additional companion analysis excludes binaries with mass ratios ≳0.5 at ≳7 au. Finally, we confirm a prevalence of Li-rich stars on the red clump that increases with lithium, which supports an evolutionary state mechanism for Li-enhancement. Multiple culprits, including binary spin-up and mass-transfer, are therefore likely mechanisms of Li-enrichment.

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“…We examined diagrams of the Gaia DR3 radial velocity error as a function of stellar color for all 63 CPVs and candidate CPVs. Since this quantity represents the standard deviation of the nonpublished Gaia radial velocity (RV) time series, outliers can suggest single-lined spectroscopic binarity (e.g., Chance et al 2022). These plots showed two clusters of stars, at 10 and 20-25 km s −1 .…”

Section: Binaritymentioning

confidence: 99%

Transient Corotating Clumps around Adolescent Low-mass Stars from Four Years of TESS

Bouma,

Jayaraman,

Rappaport

et al. 2023

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Complex periodic variables (CPVs) are stars that exhibit highly structured and periodic optical light curves. Previous studies have indicated that these stars are typically disk-free pre-main-sequence M dwarfs with rotation periods ranging from 0.2 to 2 days. To advance our understanding of these enigmatic objects, we conducted a blind search using TESS 2 minute data of 65,760 K and M dwarfs with T<16 mag and d<150 pc. We found 50 high-quality CPVs, and subsequently determined that most are members of stellar associations. Among the new discoveries are the brightest (T ≈ 9.5 mag), closest (d ≈ 20 pc), and oldest (≈200 Myr) CPVs known. One exceptional object, LP 12-502, exhibited up to eight flux dips per cycle. Some of these dips coexisted with slightly different periods, and the shortest-duration dips precisely matched the expected timescale for transiting small bodies at the corotation radius. Broadly, our search confirms that CPVs are mostly young (≲150 Myr) and low-mass (≲0.4 M ⊙). The flux dips characteristic of the class have lifetimes of ≈100 cycles, although stellar flares seem to induce a sudden dip collapse once every few months. The most plausible explanation for these phenomena remains corotating concentrations of gas or dust. The gas or dust is probably entrained by the star’s magnetic field, and the sharp features could result from a multipolar field topology, a hypothesis supported by correspondences between the light curves of CPVs and of rapidly rotating B stars known to have multipolar magnetic fields.

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paired: A Statistical Framework for Determining Stellar Binarity with Gaia RVs. I. Planet Hosting Binaries

Cited by 4 publications

References 45 publications

Spectacular Nucleosynthesis from Early Massive Stars

Spectacular Nucleosynthesis from Early Massive Stars

Many Roads Lead to Lithium: Formation Pathways For Lithium-rich Red Giants

Transient Corotating Clumps around Adolescent Low-mass Stars from Four Years of TESS

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