[Paper Review] A Quadruple or Triple Origin For Tycho B and SN 1572

Todd A. Thompson, Andrew Gould|arXiv (Cornell University)|Oct 22, 2012

Gamma-ray bursts and supernovae5 references3 citations

TL;DR

This paper proposes that Tycho B, a metal-poor A-type star at the center of the Tycho supernova remnant, originated from either a quadruple system where a K/G-type binary merged to form a blue straggler, or a triple system where it survived as the tertiary component. Both scenarios involve Kozai-Lidov oscillations and tidal friction driving binary mergers, with the observed metallicity and rotation velocity consistent with such evolutionary pathways, though kinematic inconsistencies remain a challenge.

ABSTRACT

Kerzendorf et al. (2012) recently reported the startling discovery of a metal-poor ([Fe/H]=-1 +/- 0.4) A-type star near the center of the Tycho supernova remnant. We propose two possible explanations. In the first, Tycho B is a blue straggler, formed from the merger of a close K- or G-type binary system, which was previously in a quadruple system with the binary that produced SN 1572. Both binaries were likely brought to tidal contact by Kozai-Lidov oscillations acting in concert with tidal friction. Analogous progenitor systems may include CzeV343, VW LMi, and KIC 4247791. In the second, Tycho B is the surviving tertiary component of a triple system, which was also likely affected by Kozai-Lidov oscillations. Rates are briefly discussed. Problems with each evolutionary scenario are presented. Finally, a chance alignment between Tycho B and the supernova remnant is not excluded.

Motivation & Objective

• To explain the origin of Tycho B, a metal-poor A-type star at the center of the Tycho supernova remnant, which defies standard evolutionary models.
• To investigate whether the progenitor system of SN 1572 was part of a higher-order multiple system, given the lack of obvious binary companions in the remnant.
• To assess the viability of Kozai-Lidov oscillations and tidal friction in driving binary mergers that produce blue stragglers and Type Ia supernovae.
• To evaluate the statistical likelihood of such systems existing in the Milky Way, given observed multiplicity frequencies and Kepler data.

Proposed method

• Modeling hierarchical quadruple and triple systems with A/B-A/B and K/G-K/G binaries, assuming formation in the thick disk ~10 Gyr ago.
• Applying Kozai-Lidov oscillations and tidal friction to drive inner binaries to tidal contact and eventual merger.
• Using the Mass-loss Induced Eccentric Kozai mechanism (MIEK) to explain how post-AGB mass loss triggers high eccentricity and tidal contact in massive binaries.
• Estimating occurrence rates of such systems using Kepler survey data and multiplicity statistics, particularly for eclipsing binaries.
• Comparing theoretical predictions with observed systems like CzeV343, VW LMi, and KIC 4247791 to validate the plausibility of the proposed configurations.
• Assessing kinematic and chemical consistency of Tycho B with the proposed evolutionary pathways, especially its [Fe/H] ≈ -1 and V sin i ≈ 170 km s⁻¹.

Experimental results

Research questions

• RQ1 Can the observed properties of Tycho B—its metallicity, rotation velocity, and location—be explained by a blue straggler formed via binary merger in a hierarchical multiple system?
• RQ2 Is it plausible that SN 1572 originated from a WD-WD binary merger within a quadruple or triple system, given the absence of a surviving binary companion?
• RQ3 To what extent do Kozai-Lidov oscillations and tidal friction in higher-order systems drive the formation of close binaries and blue stragglers?
• RQ4 How common are hierarchical quadruple systems with two close binaries, and is this frequency consistent with the observed rate of Type Ia supernovae?
• RQ5 Could the kinematic properties of Tycho B, consistent with a thin-disk population, be reconciled with its metal-poor origin if it formed in the thick disk and migrated?

Key findings

• The observed metallicity of Tycho B ([Fe/H] ≈ -1 ± 0.4) and its high rotation velocity (V sin i ≈ 170 km s⁻¹) are consistent with those of intermediate-mass, low-metallicity A-type blue stragglers formed via stellar mergers.
• The existence of similar systems such as CzeV343, VW LMi, and KIC 4247791 supports the plausibility of hierarchical quadruple systems with two close binaries.
• Based on Kepler data, the fraction of intermediate-mass stars in hierarchical quadruples with two close binaries is estimated at ~0.6%, with a 95% confidence interval of 0.3% to 1.8%.
• Theoretical modeling suggests that systems with A/B-A/B binaries are more susceptible to the Mass-loss Induced Eccentric Kozai mechanism (MIEK), increasing the likelihood of WD-WD mergers.
• Kinematic data indicate Tycho B is consistent with a thin-disk population, posing a challenge to the thick-disk origin hypothesis, though migration from the outer Galaxy remains a possibility.
• The rate of such systems is consistent with the observed rate of Type Ia supernovae, supporting the idea that many Ia events may originate in higher-order multiple systems.