Pre-main sequence stars in the Lagoon Nebula (M8)

Abstract

We report the discovery of new pre-main sequence (PMS) stars in the Lagoon Nebula (M8) at a distance of 1.25 kpc, based on intermediate resolution spectra obtained with the Boller & Chivens spectrograph at the 6.5-m Magellan I telescope (Las Campanas Observatory, Chile). According to the spectral types, the presence of emission lines and the lithium 6708A absorption line, we are able to identify 27 classical T Tauri stars, 7 weak-lined T Tauri stars and 3 PMS emission objects with spectral type G, which we include in a separated stellar class denominated "PMS Fe/Ge class". Using near-infrared photometry either from 2MASS or from our own previous work we derive effective temperatures and luminosities for these stars and locate them in the Hertzsprung-Russell diagram, in order to estimate their masses and ages. We find that almost all of our sample stars are younger than 3 10^6 years and span over a range of masses between 0.8 and 2.5 Msun. A cross-correlation between our spectroscopic data and the X-ray sources detected with the Chandra ACIS instrument is also presented.

18 pages, 15 figures, MNRAS, in press

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• Mid-infrared interferometry of massive young stellar objects. I. VLTI and Subaru observations of the enigmatic object M8E-IR
• Optical/Near-IR Polarization Survey of Sh 2-29: Magnetic Fields, Dense Cloud Fragmentations and Anomalous Dust Grain Sizes
• The influence of radiative core growth on coronal X-ray emission from pre-main sequence stars
• A relation between the radial velocity dispersion of young clusters and their age: Evidence for hardening as the formation scenario of massive close binaries
• GEMINI near-infrared spectroscopic observations of young massive stars embedded in molecular clouds
• Probing the anomalous extinction of four young star clusters: the use of colour-excess, main sequence fitting and fractal analysis
• Spectral classification and HR diagram of pre-main sequence stars in NGC6530
• Spectroscopic study of the extremely young O-type triple system Herschel 36 A in the Hourglass Nebula. I. Orbital properties
• The young stellar content of the giant HII regions M8, G333.6-0.2, and NGC6357 with VLT/KMOS
• Studying the effects and cause of the massive star formation in Messier 8 East
• Circumstellar disk accretion across the Lagoon Nebula: the influence of environment and stellar mass
• Geysers in the Lagoon: new Herbig-Haro objects in M8
• The Young Cluster in IC 1274
• The effects of stellar feedback on molecular clumps in the Lagoon Nebula (M8)
• Infrared variability of young solar analogs in the Lagoon Nebula