Variations on a theme -- the puzzling behaviour of Schulte 12

Abstract

One of the first massive stars detected in X-rays, Schulte 12 has remained a puzzle in several aspects. In particular, its extreme brightness both in the visible and X-ray ranges is intriguing. Thanks to Swift and XMM-Newton observations covering ~5000d, we report the discovery of a regular 108d modulation in X-ray flux of unknown origin. The minimum in the high-energy flux appears due to a combination of increased absorption and decreased intrinsic emission. We examined in parallel the data from a dedicated spectroscopic and photometric monitoring in the visible and near-IR domains, complemented by archives. While a similar variation timescale is found in those data, they do not exhibit the strict regular clock found at high energies. Changes in line profiles cannot be related to binarity but rather correspond to non-radial pulsations. Considering the substantial revision of the distance of Schulte 12 from the second GAIA data release, the presence of such oscillations agrees well with the evolutionary status of Schulte 12, as it lies in an instability region of the HR diagram.

accepted by A&A

References in corpus (15)

• The generalised Lomb-Scargle periodogram. A new formalism for the floating-mean and Keplerian periodograms
• The All-Sky Automated Survey for Supernovae (ASAS-SN) Light Curve Server v1.0
• Molecfit: A general tool for telluric absorption correction. I. Method and application to ESO instruments
• Modeling Ultraviolet Wind Line Variability in Massive Hot Stars
• BRITE-Constellation high-precision time-dependent photometry of the early-O-type supergiant $\zeta$ Puppis unveils the photospheric drivers of its small- and large-scale wind structures
• MOST detects corotating bright spots on the mid-O type giant ξ Persei
• Hot stars observed by XMM-Newton II. A survey of Oe and Be stars
• Spectral atlas of massive stars around He I 10830 A
• A new type of X-ray pulsar
• CIR Modulation of the X-ray Flux from the O7.5 III(n)((f)) Star xi Persei?
• High resolution optical spectroscopy of an LBV-candidate inside the CygOB2 association
• Spectroscopic and photometric oscillatory envelope variability during the S Doradus outburst of the Luminous Blue Variable R71
• e-MERLIN 21cm constraints on the mass-loss rates of OB stars in Cyg OB2
• X-ray mapping of the stellar wind in the binary PSR J2032+4127/MT91 213
• On the binary nature of massive blue hypergiants: high-resolution X-ray spectroscopy suggests that Cyg OB2 12 is a colliding wind binary

Cited by in corpus (6)

• Detection of PAH Absorption and Determination of the Mid-Infrared Diffuse Interstellar Extinction Curve from the Sightline Toward Cyg OB2-12
• Velocity monitoring of gamma-Cas stars reveals their binarity status
• Multiplicity of Galactic Luminous Blue Variable stars
• Upper Mass-Loss Limits and Clumping in the Intermediate and Outer Wind Regions of OB stars
• Galactic extinction laws: I. A global NIR analysis with 2MASS photometry
• X-ray emission of massive stars and their winds