Mira Variable Stars From LAMOST DR4 Data: Emission Features, Temperature Types, and Candidate Selection

Abstract

Based on an extensive spectral study of a photometrically confirmed sample of Mira variables, we find a relationship between relative Balmer emission-line strength and spectral temperature of O-rich Mira stars. The $F_{\mathrm{H}\delta }/F_{\mathrm{H}\gamma }$ flux ratio increases from less than unity to five as stars cool down from M0 to M10, which is likely driven by increasing TiO absorption above the deepest shock-emitting regions. We also discuss the relationship between the equivalent widths of the Balmer emission lines and the photometric luminosity phase of our Mira sample stars. Using our 291 Mira spectra as templates for reference, 191 Mira candidates are newly identified from the LAMOST DR4 catalog. We summarize the criteria adopted to select Mira candidates based on emission-line indices and molecular absorption bands. This enlarged spectral sample of Mira variables has the potential to contribute significantly to our knowledge of the optical properties of Mira stars and will facilitate further studies of these late-type, long-period variables.

21 pages; ApJS, in press

References in corpus (24)

• The generalised Lomb-Scargle periodogram. A new formalism for the floating-mean and Keplerian periodograms
• Evolution of asymptotic giant branch stars II. Optical to far-infrared isochrones with improved TP-AGB models
• The First Data Release (DR1) of the LAMOST general survey
• LAMOST Experiment for Galactic Understanding and Exploration (LEGUE) The survey science plan
• Northern Sky Variability Survey (NSVS): Public data release
• An Optical Spectroscopic Study of T Tauri Stars. I. Photospheric Properties
• AGB Variables and the Mira Period-Luminosity Relation
• The distance to the giant elliptical galaxy NGC 5128
• They might be giants: luminosity class, planet frequency, and planet-metallicity relation of the coolest Kepler target stars
• A near-infrared survey of Miras and the distance to the Galactic Centre
• The Age and Structure of the Galactic Bulge from Mira Variables
• Innocent Bystanders: Carbon Stars from the Sloan Digital Sky Survey
• The Clouds are breaking: tracing the Magellanic system with Gaia DR1 Mira variables
• Carbon stars from LAMOST DR2 data
• Galactic distributions of carbon- and oxygen-rich AGB stars revealed by the AKARI mid-infrared all-sky survey
• The structure of radiative shock waves. V. Hydrogen emission lines
• SiO Maser Survey of the Inner Bar of the Galactic Bulge
• Absence of an X-shaped Structure in the Milky Way Bulge Using Mira Variable Stars
• Discovery of carbon-rich Miras in the Galactic bulge
• An SiO Maser Search off the Galactic Plane
• SiO Maser Survey off the Galactic Plane: A Signature of Streaming Motion
• Phase Dependent Spectroscopy of Mira Variable Stars
• Optical spectra of selected Chamaeleon I young stellar objects
• Oxygen- and carbon-rich variable red giant populations in the Magellanic Clouds from EROS, OGLE, MACHO, and 2MASS photometry

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• The OGLE Collection of Variable Stars. Nearly 66,000 Mira stars in the Milky Way
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• Hunting for C-rich long-period variable stars in the Milky Way's bar-bulge using unsupervised classification of Gaia BP/RP spectra
• Relativistic corrections for measuring Hubble's constant to 1% using stellar standard candles
• Discovery of 2716 hot emission-line stars from LAMOST DR5
• Searching for Anomalies in the ZTF Catalog of Periodic Variable Stars
• Eclipsing Binary Populations across the Northern Galactic Plane from the KISOGP survey
• Multiwavelength study of 1eRASS J085039.9-421151 with eROSITA NuSTAR and X-shooter
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