James Webb Space Telescope Feed Post

Arxiv: JWST/NIRSpec Observations of Brown Dwarfs in the Orion Nebula Cluster Published: 10/13/2024 11:45:26 PM Updated: 10/13/2024 11:45:26 PM

Paper abstract: We have used the multiobject mode of the Near-Infrared Spectrograph (NIRSpec)on board the James Webb Space Telescope (JWST) to obtain low-resolution 1-5umspectra of 22 brown dwarf candidates in the Orion Nebula Cluster, which wereselected with archival images from the Hubble Space Telescope. One of thetargets was previously classified as a Herbig-Haro (HH) object and exhibitsstrong emission in H I, H2, and the fundamental band of CO, furtherdemonstrating that HH objects can have bright emission in that CO band. Theremaining targets have late spectral types (M6.5 to early L) and are youngbased on gravity sensitive features, as expected for low-mass members of thecluster. According to theoretical evolutionary models, these objects shouldhave masses that range from the hydrogen burning limit to 0.003-0.007 Msun. Twoof the NIRSpec targets were identified as proplyds in earlier analysis ofHubble images. They have spectral types of M6.5 and M7.5, making them two ofthe coolest and least massive known proplyds. Another brown dwarf showsabsorption bands at 3-5um from ices containing H2O, CO2, OCN-, and CO,indicating that it is either an edge-on class II system or a class I protostar.It is the coolest and least massive object that has detections of these icefeatures. In addition, it appears to be the first candidate for a protostellarbrown dwarf that has spectroscopy confirming its late spectral type.