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We present observations of the X‐ray and ultraviolet emission from a sample of dwarf stars in the Arcturus Moving Group. The Arcturus Moving Group is very likely a remnant of the merger of a dwarf galaxy with the Milky Way Galaxy in the distant past. This kinematically distinct group has members located very close to the Sun, allowing study of stellar activity on very old (7–8 Gyr), low metallicity stars that would typically not be possible. Our sample has metallicities between 0.4 and 0.04 solar, spectral types F9—mid‐M, and distances less than 25 pc from the Sun. We have detected X‐ray emission from five AMG dwarfs with the Chandra ACIS‐S S3 back‐illuminated detector and for four stars have measured or placed upper limits on the C IV UV1 emission flux using GALEX GRISM spectra. The measured X‐ray luminosities are comparable to the minimum solar Lx (range 6–20 1026 erg s−1 for 0.24–2.0 keV) and for the late G/early K stars are also similar to that of the inactive, more metal rich ([Fe/H] = −0.42] G8 dwar...

Carbon monoxide has been detected in Betelgeuse’s ultraviolet (electronic), infrared (vibrational), and mm‐radio (rotational) spectra, but its spatial distribution has remained elusive. We have obtained new mm‐radio interferometry (CARMA), infrared spatially‐resolved spectra (Phoenix/Gemini‐South), and we have performed non‐LTE simulations to help establish the spatial location of the S1 (V = 10 km/s) and S2 (V = 17 km/s) CO shells. The strong CO Fourth‐Positive ultraviolet scattering signature is apparent in the HST GHRS G140L spectrum and the S1 and S2 shells account for much of the UV opacity. Phoenix spectra reveal that the low velocity S1 shell is present at 1.5 arcsec West of the star and extends out to ∼4 arcsec, and its mm‐radio emission appears to originate within an 6 arcsec radius. The interpretation of the S2 shell is less clear. The Phoenix spectra tentatively suggest that the S2 shell extends to ∼7 arcsec. The CARMA channel maps show an additional strong narrow emission component 5 arcsec fr...

The environment of the nearest Herbig Ae star has been investigated through a program of multi‐wavelength, high contrast and high spatial resolution imagery, FUV through optical integrated light spectroscopy, and FUV spatially resolved spectroscopy. HD 104237 is the primary of a 5 Myr old aggregate of at least 4 PMS stars, 2 of which in addition to HD 104237 have IR excesses indicating the presence of dust disks. HD 104237 is actively accreting, and is driving a bipolar outflow (HH 669) which can be traced 2.65″ from the star and which is viewed at an inclination of18−11+14°. The counterjet can be traced no closer than 0.6″ (79 AU) from the star, providing a firm upper limit to the size of the disk. The absence of spatially extended H2 emission, FUV reflection nebulosity, and mid‐IR PAH emission features are all consistent with dust settling and the presence of a geometrically shadowed disk. The combination of proximity, low reddening, and the high density of disks in the HD 104237 association make this g...