A Spectroscopic and Interferometric Study of W Serpentis Stars. I. Circumbinary Outflow in the Interacting Binary W Serpentis

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Hauptverfasser: Shepard, Katherine, Gies, Douglas R., Schaefer, Gail H., Anugu, Narsireddy, Baron, Fabien R., Lanthermann, Cyprien, Monnier, John D., Kraus, Stefan, Brummelaar, Theo ten
Format: Preprint
Veröffentlicht: 2025
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author Shepard, Katherine
Gies, Douglas R.
Schaefer, Gail H.
Anugu, Narsireddy
Baron, Fabien R.
Lanthermann, Cyprien
Monnier, John D.
Kraus, Stefan
Brummelaar, Theo ten
author_facet Shepard, Katherine
Gies, Douglas R.
Schaefer, Gail H.
Anugu, Narsireddy
Baron, Fabien R.
Lanthermann, Cyprien
Monnier, John D.
Kraus, Stefan
Brummelaar, Theo ten
contents W Serpentis is an eclipsing binary system and the prototype of the Serpentid class of variable stars. These are interacting binaries experiencing intense mass transfer and mass loss. However, the identities and properties of both stars in W Ser remain a mystery. Here we present an observational analysis of high quality, visible-band spectroscopy made with the Apache Point Observatory 3.5 m telescope and ARCES spectrograph plus the first near-IR, long-baseline interferometric observations obtained with the CHARA Array. We present examples of the appearance and radial velocities of the main spectral components: prominent emission lines, strong shell absorption lines, and weak absorption lines. We show that some of the weak absorption features are associated with the cool mass donor, and we present the first radial velocity curve for the donor star. The donor's absorption lines are rotationally broadened, and we derive a ratio of donor to gainer mass of 0.36 +/- 0.09 based on the assumptions that the donor fills its Roche lobe and rotates synchronously with the orbit. We use a fit of the ASAS light curve to determine the orbital inclination and mass estimates of 2.0 and 5.7 solar masses for the donor and gainer, respectively. The partially resolved interferometric measurements of orbital motion are consistent with our derived orbital properties and the distance from Gaia EDR3. Spectroscopic evidence indicates that the gainer is enshrouded in an opaque disk that channels the mass transfer stream into an outflow through the L3 region and into a circumbinary disk.
format Preprint
id arxiv_https___arxiv_org_abs_2501_06982
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle A Spectroscopic and Interferometric Study of W Serpentis Stars. I. Circumbinary Outflow in the Interacting Binary W Serpentis
Shepard, Katherine
Gies, Douglas R.
Schaefer, Gail H.
Anugu, Narsireddy
Baron, Fabien R.
Lanthermann, Cyprien
Monnier, John D.
Kraus, Stefan
Brummelaar, Theo ten
Solar and Stellar Astrophysics
W Serpentis is an eclipsing binary system and the prototype of the Serpentid class of variable stars. These are interacting binaries experiencing intense mass transfer and mass loss. However, the identities and properties of both stars in W Ser remain a mystery. Here we present an observational analysis of high quality, visible-band spectroscopy made with the Apache Point Observatory 3.5 m telescope and ARCES spectrograph plus the first near-IR, long-baseline interferometric observations obtained with the CHARA Array. We present examples of the appearance and radial velocities of the main spectral components: prominent emission lines, strong shell absorption lines, and weak absorption lines. We show that some of the weak absorption features are associated with the cool mass donor, and we present the first radial velocity curve for the donor star. The donor's absorption lines are rotationally broadened, and we derive a ratio of donor to gainer mass of 0.36 +/- 0.09 based on the assumptions that the donor fills its Roche lobe and rotates synchronously with the orbit. We use a fit of the ASAS light curve to determine the orbital inclination and mass estimates of 2.0 and 5.7 solar masses for the donor and gainer, respectively. The partially resolved interferometric measurements of orbital motion are consistent with our derived orbital properties and the distance from Gaia EDR3. Spectroscopic evidence indicates that the gainer is enshrouded in an opaque disk that channels the mass transfer stream into an outflow through the L3 region and into a circumbinary disk.
title A Spectroscopic and Interferometric Study of W Serpentis Stars. I. Circumbinary Outflow in the Interacting Binary W Serpentis
topic Solar and Stellar Astrophysics
url https://arxiv.org/abs/2501.06982