The Discovery of lambda Bootis Stars -- The Southern Survey II

Abstract

The $\lambda$ Boo stars are chemically peculiar A-type stars whose abundance anomalies are associated with the accretion of metal-poor material. We searched for $\lambda$ Boo stars in the southern hemisphere in a targeted spectroscopic survey of metal-weak and emission-line stars. Obtaining spectra for 308 stars and classifying them on the MK system, we found or co-discovered 24 new $\lambda$ Boo stars. We also revised the classifications of 11 known $\lambda$ Boo stars, one of which turned out to be a chemically normal rapid rotator. We show that stars previously classified in the literature as blue horizontal branch stars or emission-line A stars have a high probability of being $\lambda$ Boo stars, although this conclusion is based on small-number statistics. Using WISE infrared fluxes, we searched our targets for infrared excesses that might be attributable to protoplanetary or debris discs as the source of the accreted material. Of the 34 $\lambda$ Boo stars in our sample, 21 at various main-sequence ages have infrared excesses, confirming that not all $\lambda$ Boo stars are young.

arXiv commentAccepted for publication in MNRAS. Figures do not have heavy reliance on colour. Online data will be hosted with the journal / Vizier@CDS

References in corpus (50)

• Gaia Data Release 2. Summary of the contents and survey properties
• Correcting for the Effects of Interstellar Extinction
• The SIMBAD astronomical database
• Estimating distances from parallaxes IV: Distances to 1.33 billion stars in Gaia Data Release 2
• The K2 Mission: Characterization and Early results
• A giant planet imaged in the disk of the young star Beta Pictoris
• The Wide Field Spectrograph (WiFeS)
• Planet Hunters X. KIC 8462852 - Where's the Flux?
• ALMA unveils rings and gaps in the protoplanetary system HD 169142: signatures of two giant protoplanets
• Close encounters of the stellar kind
• Spectrophotometric Libraries, Revised Photonic Passbands and Zero-points for UBVRI, Hipparcos and Tycho Photometry
• A 40 Myr Old Gaseous Circumstellar Disk at 49 Ceti: Massive CO-Rich Comet Clouds at Young A-Type Stars
• {\em Gaia}-derived luminosities of {\em Kepler} A/F stars and the pulsator fraction across the δ Scuti instability strip
• PyWiFeS: A Rapid Data Reduction Pipeline for the Wide Field Spectrograph (WiFeS)
• Fingerprints of giant planets in the photospheres of Herbig stars
• Chemical abundances of magnetic and non-magnetic Herbig Ae/Be stars
• The mass of the young planet Pictoris b through the astrometric motion of its host star
• A Precise Determination of the Mid-Infrared Interstellar Extinction Law Based on the APOGEE Spectroscopic Survey
• A search for accreting young companions embedded in circumstellar disks: High-contrast H$\alpha$ imaging with VLT/SPHERE
• Investigation of the inner structures around HD169142 with VLT/SPHERE
• KIC 8462852: Transit of a Large Comet Family
• Transiting exocomets detected in broadband light by TESS in the $\beta$ Pictoris system
• Blobs, spiral arms, and a possible planet around HD 169142
• The status of Galactic field lambda Bootis stars in the post-Hipparcos era
• The lambda Bootis phenomenon: interaction between a star and a diffuse interstellar cloud
• Gaia's view of the $\lambda$ Boo star puzzle
• Characterization of Ring Substructures in the Protoplanetary Disk of HD 169142 from Multi-Wavelength ALMA Observations
• Asteroseismology of KIC 11754974: a high-amplitude SX Phe pulsator in a 343-day binary system
• Characterization of the inner disk around HD 141569 A from Keck/NIRC2 L-band vortex coronagraphy
• Probing midplane CO abundance and gas temperature with DCO${}^{+}$ in the protoplanetary disk around HD 169142
• An evaluation of the membership probability of 212 $\lambda$ Boo stars: I. A Catalogue
• Long lived dust rings around HD169142
• Inner disk clearing around the Herbig Ae star HD\,139614: Evidence for a planet-induced gap ?
• Irregular dust features around intermediate-mass young stars with GPI: signs of youth or misaligned disks?
• Planets of Beta Pictoris revisited
• The compact H$\alpha$ emitting regions of the Herbig Ae/Be stars HD 179218 and HD 141569 from CHARA spectro-interferometry
• IAU 2015 Resolution B2 on Recommended Zero Points for the Absolute and Apparent Bolometric Magnitude Scales
• A gas density drop in the inner 6 AU of the transition disk around the Herbig Ae star HD 139614: Further evidence for a giant planet inside the disk?
• Stellar Photospheric Abundances as a Probe of Disks and Planets
• Lambda Boo Abundance Patterns: Accretion from Orbiting Sources
• Unlocking the secrets of the midplane gas and dust distribution in the young hybrid disc HD 141569
• Six new rapidly oscillating Ap stars in the Kepler long-cadence data using super-Nyquist asteroseismology
• The Pulsation Properties of $\lambda$ Bootis Stars I. The Southern TESS Sample
• Spectroscopic signatures of magnetospheric accretion in Herbig Ae/Be stars. I. The case of HD101412
• ALMA and VLA Observations of the HD 141569 System
• Imaging the 44 AU Kuiper Belt-analogue debris ring around HD 141569A with GPI polarimetry
• Investigating the possible connection between lambda Bootis stars and intermediate Population II type stars
• Variable warm dust around the Herbig Ae star HD~169142: Birth of a ring?
• The narrow, inner CO ring around the magnetic Herbig Ae star, HD 101412
• An Encoding System to Represent Stellar Spectral Classes in Archival Databases and Catalogs

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• A precise asteroseismic age and metallicity for HD 139614: a pre-main-sequence star with a protoplanetary disc in Upper-Centaurus Lupus
• A Novel Method to Estimate the FUV Flux and a Catalogue for Star-Hosting Discs in Nearby Star-Forming Regions
• An interferometric study of B star multiplicity
• Testing the accretion scenario of lambda Boo stars
• Searching for lambda Boo stars in binary systems
• Discovery of lambda Boo stars in open clusters
• Drifters on the edge of town: $\lambda$ Boötis stars in clusters