Long period Ap stars discovered with TESS data

Abstract

The TESS space mission is producing superb data for asteroseismology, eclipsing binary stars, gyrochronology, and other fields of stellar astronomy where the data are variable light curves. We show that TESS data are excellent for astrophysical inference from peculiar stars that show variability. The Ap stars have the strongest magnetic fields of any main-sequence stars. Some have been shown to have rotation periods of months to centuries. The astrophysical cause of their slow rotation -- the braking mechanism -- is not known with certainty. These stars are rare: there are currently about 3 dozen with known periods. The magnetic Ap stars have long-lived spots that allow precise determination of their rotation periods. We show that most Ap stars with TESS data that show no low-frequency variability must have rotation periods longer than a TESS sector of 27 d. We find 60 Ap stars in the southern ecliptic hemisphere TESS data with no rotational variability, of which at most a few can be pole-on, and six likely have nearly aligned magnetic and rotation axes. Of the other 54, 31 were previously known to have long rotation periods or low projected equatorial velocities, which proves our technique; 23 are new discoveries. These are prime targets for long-term magnetic studies. We also find that 22 per cent of long-period Ap stars are roAp stars, versus only 3 per cent of the other Ap stars studied with TESS sector 1 and 2 data. This work demonstrates astrophysical inference from nonvariable stars -- "something for nothing".

arXiv commentAccepted for publication in A&A; 19 pages, 11 figures

References in corpus (31)

• The Transiting Exoplanet Survey Satellite
• The MiMeS survey of magnetism in massive stars: Magnetic analysis of the O-type stars
• Evolutionary state of magnetic chemically peculiar stars
• {\em Gaia}-derived luminosities of {\em Kepler} A/F stars and the pulsator fraction across the δ Scuti instability strip
• Theory and evidence of global Rossby waves in upper main-sequence stars: r-mode oscillations in many Kepler stars
• Ap stars with resolved magnetically split lines: Magnetic field determinations from Stokes $I$ and $V$ spectra
• The Magnetic Early B-type Stars I: Magnetometry and Rotation
• A Volume Limited Survey of mCP Stars Within 100pc II: Rotational and Magnetic Properties
• High frequency A-type pulsators discovered using SuperWASP
• An Investigation of the Rotational Properties of Magnetic Chemically Peculiar Stars
• B fields in OB stars (BOB): Concluding the FORS2 observing campaign
• The FORS1 catalogue of stellar magnetic field measurements
• Rotation and pulsation in Ap stars: first light results from TESS sectors 1 and 2
• Magnetic OB[A] Stars with TESS: probing their Evolutionary and Rotational properties (MOBSTER) - I. First-light observations of known magnetic B and A stars
• Discovery of 17 new sharp-lined Ap stars with magnetically resolved lines
• A high-resolution spectropolarimetric survey of Herbig Ae/Be stars - II. Rotation
• Evolution of Magnetic Fields in Stars Across the Upper Main Sequence: II. Observed distribution of the magnetic field geometry
• The applications of the MHD Alfven wave oscillation model for kHz quasi-periodic oscillations
• Periods of magnetic field variations in the Ap star $\gamma$ Equulei (HD 201601)
• HD66051: the first eclipsing binary hosting an early-type magnetic star
• Discovery of new roAp pulsators in the UVES survey of cool magnetic Ap stars
• Suppressed phase variations in a high amplitude rapidly oscillating Ap star pulsating in a distorted quadrupole mode
• HD 99458: First time ever Ap-type star as a $\delta$ Scuti pulsator in a short period eclipsing binary?
• MOBSTER -- III. HD 62658: a magnetic Bp star in an eclipsing binary with a non-magnetic 'identical twin'
• HD 18078: A very slowly rotating Ap star with an unusual magnetic field structure
• Magnetic stars from a FEROS cool Ap star survey
• The variation of the magnetic field of the Ap star HD~50169 over its 29 year rotation period
• Short time-scale frequency and amplitude variations in the pulsations of an roAp star: HD 217522
• HD 965: An extremely peculiar A star with an extremely long rotation period
• The 10.5 year rotation period of the strongly magnetic rapidly oscillating Ap star HD 166473
• Time resolved spectroscopy of the cool Ap star HD 213637

Cited by in corpus (19)

• On the first $\delta$ Sct--roAp hybrid pulsator and the stability of p and g modes in chemically peculiar A/F stars
• Periodic variable A-F spectral type stars in the northern TESS continuous viewing zone
• TESS Cycle 1 observations of roAp stars with 2-min cadence data
• Highlights of Discoveries for $\delta$ Scuti Variable Stars From the Kepler Era
• TESS Data for Asteroseismology (T'DA) Stellar Variability Classification Pipeline: Set-Up and Application to the Kepler Q9 Data
• Photometric variability of the LAMOST sample of magnetic chemically peculiar stars as seen by TESS
• Long-period Ap stars discovered with TESS data: The northern ecliptic hemisphere
• Analysis of high-resolution FEROS spectroscopy for a sample of variable B-type stars assembled from TESS photometry
• The roAp stars observed by the Kepler Space Telescope
• An Ap star catalog based on LAMOST DR9
• HD 60431, the CP2 star with the shortest rotational period -- Physical parameters and period analysis
• MOCKA -- A PLATO mock asteroseismic catalogue: Simulations for gravity-mode oscillators
• A new sample of super-slowly rotating Ap (ssrAp) stars from the Zwicky Transient Facility survey
• Confident Detection of Doubly-Ionized Thorium in the Extreme Ap Star CPD-62 2717
• SALT HRS capabilities for time resolved pulsation analysis: a test with the roAp star $\alpha$ Circini
• Super-slowly rotating Ap (ssrAp) stars: New spectroscopic observations
• Magnetic field measurements of sharp-lined Ap stars
• Two New roAp Stars Discovered with TESS
• The symphony of pulsations and binarity among massive stars using HERMES spectroscopy and TESS photometry