We report subarcsecond-resolution VLA and Keck mid-infrared imaging of the dwarf starburst galaxy II Zw 40. II Zw 40 contains a bright, compact thermal radio and infrared source with all the the characteristics of a collection of dense HII regions ionized by at least 14,000 O stars. The supernebula is revealed to be multiple sources within an envelope of weaker emission. The radio emission is dominated by free-free emission at 2 cm, and the spectrum of this emission appears to be rising. This suggests that the free-free emission is optically thick at 2 cm, and that the individual HII regions are ∼1 pc in size. This complex of "supernebulae" dominates the total infrared luminosity of II Zw 40, although the radio source is less than ∼150 pc in diameter. Multiple super star clusters appear to be forming here, the much larger analogues of large Galactic HII region complexes.

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Element inhomogeneities are studied in the second-parameter pair of globular clusters NGC 288 and NGC 362. Spectra obtained with the CTIO 1.5 m telescope of relatively high luminosity red giants (M V < À1:0) in each cluster have been used to measure a λ3883 CN band index denoted Sð3839Þ, and two indices centered on CH absorption in the λ4300 G band. Giants in both clusters exhibit a comparable spread in CN band strength, with only a small difference in mean G band absorption between CN-strong and CN-weak giants. By contrast, the Sð3839Þ index anticorrelates with the [O/Fe] abundance measured by Shetrone & Keane. Part of this anticorrelation can be explained by the effect of reduced oxygen on the equilibria of CO and CN molecule formation in red giant atmospheres. However, the difference in Sð3839Þ between CN-weak and CN-strong giants is sufficiently large that a factor of ∼10 enhancement in nitrogen in CN-strong stars also appears to be necessary. Additionally, the 3883 Å CN band strength correlates with [Na/Fe] abundance. These CN-O-Na relationships among the red giants of NGC 362 and NGC 288 are also a characteristic of other globular clusters of the Milky Way. At a given Sð3839Þ and [Na/Fe] abundance, the CN-strong red giants of NGC 288 have a higher oxygen abundance than red giants in NGC 362. As such, NGC 288 and NGC 362 do not appear to follow a correlation between minimum [O/Fe] abundance and the blueward extent of the horizontal branch in the color-magnitude diagram.

We present high-resolution High Resolution Echelle Spectrometer (HIRES)/Keck spectra of HD 209458, and a Monte Carlo variation on the basic method used by other workers, to look for the excess in-transit absorption in the NaD doublet at 5893 Å due to the extrasolar planet. The HIRES data, binned by bandpass, allow a direct comparison with previous results. We find >3σ results in most test bandpasses around the NaD doublet, including relative absorption of (−108.8 ± 25.7) × 10 −5 in the "narrow" bandpass used by other workers. This is ≈4.7 times larger than the "narrow" results reported by Charbonneau et al. for HD 209458b. However, >2σ absorption is detected in some weak Fe i and Ni i lines that were tested for comparison, raising concern about the uncertainties introduced by continuum-fitting and terrestrial atmosphere subtraction.

We report spectra from 3000-5900 A for comet 96P/Machholz, obtained on 2007 Apr 27 UT with the 3-m Shane telescope at Lick Observatory. The spectra are extremely carbon poor, and show a prominent NH_2 series, but no CN emission. NH, NH_2, and C_2 gas production rates are (8.36 +/- 2.18)x10^25, (29.88 +/- 3.66)x10^25, and (4.52 +/- 0.61)x10^23 molecules sec^-1, respectively, as determined from Haser model fits to the data. Upper limits to the gas production rates for CN and C_3 are 7.5x10^22 and 2.0x10^23, respectively. Though 96P is depleted in C_2 and C_3 relative to NH, it is even more depleted in CN than other so-called "carbon-chain depleted" comets.Comment: 14 pages, 4 tables, 2 figures, accepted for publication in ApJ