Exploring Be phenomena in OBA stars: a Mid-infrared search
arXiv:2311.08395 · doi:10.1051/0004-6361/202347911
Abstract
As early-type stars with a rotation speed close to their critical velocity, Be stars experience an event called the Be phenomenon. The material in their equator is ejected into outside space during the Be phenomenon and forms a circumstellar disk. The mechanism triggering these events remains poorly understood, and observations of these events are limited because the duration of these events ranges from months to years. Long-term epoch photometry in the infrared bands is expected to be ideal for detecting Be phenomena because the brightness variation is larger, and the effect of interstellar extinction is weaker as well. We conducted a systematic search for Be phenomena among Milky Way OBA stars in the mid-infrared. We examined the brightness and colour variations of known classical Be stars using the WISE W1 and W2 photometry bands to quantify their characteristics. Subsequently, we established a set of criteria to identify similar photometric variations in a large sample of OBA stars. We found 916 OBA stars that show Be phenomena in the past 13 years, 736 of which are newly discovered. The peak-to-peak variations in magnitude and colour were found to be correlated, indicating that a decretion disk is common. The increase in colour was observed to be strongly correlated with the emission of the H-alpha line, providing further evidence of the association with circumstellar disks. The brightness variation of a star with Be phenomena can be up to 1.5 mag, and the colour variations can be up to 0.4 mag. The median durations for the disk build-up and decay phases are 474 and 524 days, respectively (durations shorter than 180 days are not sampled). The search for Be phenomena in the WISE bands greatly enlarges the number of stars showing disk variation, and it enables multi-band photometry analysis of these events with the help of current and future optical photometry surveys.
arXiv comment14 pages, 16 figures, 5 tables, accepted for publication in A&A
References in corpus (34)
- The Wide-field Infrared Survey Explorer (WISE): Mission Description and Initial On-orbit Performance
- PARSEC: stellar tracks and isochrones with the PAdova and TRieste Stellar Evolution Code
- The Apache Point Observatory Galactic Evolution Experiment (APOGEE)
- The All-Sky Automated Survey for Supernovae (ASAS-SN) Light Curve Server v1.0
- Preliminary Results from NEOWISE: An Enhancement to the Wide-field Infrared Survey Explorer for Solar System Science
- Classical Be Stars: Rapidly Rotating B Stars with Viscous Keplerian Decretion Disks
- Painting a portrait of the Galactic disc with its stellar clusters
- LAMOST Experiment for Galactic Understanding and Exploration (LEGUE) The survey science plan
- The Gaia-ESO Public Spectroscopic Survey: Implementation, data products, open cluster survey, science, and legacy
- YBC, a stellar bolometric corrections database with variable extinction coefficients: an application to PARSEC isochrones
- The Gaia-ESO Public Spectroscopic Survey: Motivation, implementation, GIRAFFE data processing, analysis, and final data products
- Viscous Transonic Decretion in Disks of Be Stars
- Dynamical Evolution of Viscous Disks around Be Stars. I: photometry
- Gaia Data Release 3: All-sky classification of 12.4 million variable sources into 25 classes
- Wide-field Infrared Survey Explorer (WISE) Catalog of Periodic Variable Stars
- On Be Star Candidates and Possible Blue Pre-Main Sequence Objects in the Small Magellanic Cloud
- A Precise Determination of the Mid-Infrared Interstellar Extinction Law Based on the APOGEE Spectroscopic Survey
- Catalogue of new Herbig Ae/Be and classical Be stars. A machine learning approach to Gaia DR2
- Photometric Variability of the Be Star Population
- High-resolution, H band Spectroscopy of Be Stars with SDSS-III/APOGEE: I. New Be Stars, Line Identifications, and Line Profiles
- 3D Morphology of Open Clusters in the Solar Neighborhood with Gaia EDR3 II: Hierarchical Star Formation Revealed by Spatial and Kinematic Substructures
- APOGEE Net: An expanded spectral model of both low mass and high mass stars
- Flux rope proxies and fan-spine structures in active region NOAA 11897
- Red supergiant stars in the Large Magellanic Cloud. II. Infrared properties and mid-infrared variability
- Revision of Stellar Intrinsic Colors in the Infrared by the Spectroscopic Surveys
- Data-driven spectroscopic estimates of absolute magnitude, distance and binarity -- method and catalog of 16,002 O- and B-type stars from LAMOST
- A deep catalogue of classical Be stars in the direction of the Perseus Arm: spectral types and interstellar reddenings
- An investigation of the photometric variability of confirmed and candidate Galactic Be stars using ASAS-3 data
- A catalog of early-type Hα emission line stars and 58 newly confirmed Herbig Ae/Bes from LAMOST DR7
- Identification of new classical Be stars from the LAMOST MRS survey
- Exploring the stellar rotation of early-type stars in the LAMOST Medium-Resolution Survey. I. Catalog
- Quiescent and active phases in Be stars: A WISE snapshot of young galactic open clusters
- Intrinsic Color Indices of Early-Type Dwarf Stars
- A survey for variable young stars with small telescopes: VI -- Analysis of the outbursting Be stars NSW284, Gaia19eyy, and VES263