Article

The SNIa Runaway LP 398-9: Detection of Circumstellar Material and Surface Rotation

Vedant ChandraCenter for Astrophysics ∣ Harvard & Smithsonian , 60 Garden St, Cambridge, MA 02138, USAHsiang-Chih HwangInstitute for Advanced Study , Einstein Drive, Princeton, NJ 08540, USANadia L. ZakamskaDepartment of Physics & Astronomy, Johns Hopkins University , 3400 N Charles St, Baltimore, MD 21218, USASimon BlouinLos Alamos National Laboratory , PO Box 1663, Los Alamos, NM 87545, USAAndrew SwanDepartment of Physics & Astronomy, University College London , Gower Street, London WC1E 6BT, UKT. R. MarshDepartment of Physics, University of Warwick , Coventry, CV4 7AL, UKKen J. ShenDepartment of Astronomy and Theoretical Astrophysics Center, University of California , Berkeley, CA 94720, USAG\"ansicke, Boris T.Department of Physics, University of Warwick , Coventry, CV4 7AL, UKJ. J. HermesDepartment of Astronomy & Institute for Astrophysical Research, Boston University , 725 Commonwealth Ave., Boston, MA 02215, USAOdelia PuttermanDepartment of Astronomy & Institute for Astrophysical Research, Boston University , 725 Commonwealth Ave., Boston, MA 02215, USAEvan B. BauerCenter for Astrophysics ∣ Harvard & Smithsonian , 60 Garden St, Cambridge, MA 02138, USAEvan PetroskyDepartment of Physics, University of Michigan , 450 Church St, Ann Arbor, MI 48109, USAV. S. DhillonDepartment of Physics and Astronomy, University of Sheffield , Sheffield S3 7RH, UKS. P. LittlefairDepartment of Physics and Astronomy, University of Sheffield , Sheffield S3 7RH, UKR. P. AshleyIsaac Newton Group of Telescopes , Apartado de Correos 321, Santa Cruz de La Palma, E-38700, Spain

2021en

ABI

Abstract

A promising progenitor scenario for Type Ia supernovae (SNeIa) is the thermonuclear detonation of a white dwarf in a close binary system with another white dwarf. After the primary star explodes, the surviving donor can be spontaneously released as a hypervelocity runaway. One such runaway donor candidate is LP 398-9, whose orbital trajectory traces back $\approx 10^5$ years to a known supernova remnant. Here we report the discovery of carbon-rich circumstellar material around LP 398-9, revealed by a strong infrared excess and analyzed with follow-up spectroscopy. The circumstellar material is most plausibly composed of inflated layers from the star itself, mechanically and radioactively heated by the past companion's supernova. We also detect a 15.4 hr periodic signal in the UV and optical light curves of LP 398-9, which we interpret as surface rotation. The rotation rate is consistent with theoretical predictions from this supernova mechanism, and the brightness variations could originate from surface inhomogeneity deposited by the supernova itself. Our observations strengthen the case for this double-degenerate SNIa progenitor channel, and motivate the search for more runaway SNIa donors.

Identifiers

DOI: 10.1093/mnras/stac883

Citations and references

Cited by 10 references

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