The AM Canum Venaticorum binary SDSS J173047.59+554518.5

The AM Canum Venaticorum (AM CVn) binaries are a rare group of hydrogen-deficient, ultrashort period, mass-transferring white dwarf binaries and are possible progenitors of Type Ia supernovae. We present time-resolved spectroscopy of the recently discovered AM CVn binary SDSS J173047.59+554518.5. The average spectrum shows strong double-peaked helium emission lines, as well as a variety of metal lines, including neon; this is the second detection of neon in an AM CVn binary, after the much brighter system GP Com. We detect no calcium in the accretion disc, a puzzling feature that has been noted in many of the longer period AM CVn binaries. We measure an orbital period, from the radial velocities of the emission lines, of 35.2 ± 0.2 min, confirming the ultracompact binary nature of the system. The emission lines seen in SDSS J1730 are very narrow, although double-peaked, implying a low-inclination, face-on accretion disc; using the measured velocities of the line peaks, we estimate i ≤ 11°. This low inclination makes SDSS J1730 an excellent system for the identification of emission lines

Initiation and Termination of Oriental Fruit Moth Male Response to Pheromone Concentrations in the Field

The distance from the pheromone source at which Grapholitha molesta (Busck) males initiated walking, upwind flight, or wing fanning while walking varied directly with the pheromone emission rate. Roughly a 10-fold increase in emission rate resulted in a ca. 2-fold increase in mean maximum distance for initiation of these behaviors. Also, an apparent upper concentration threshold in males caused upwind flight to be terminated at increasing distances from the source with increasing emission rates. Thus, upper and lower thresholds apparently determine the boundaries of the "active distance” for upwind flight. There was much daily variation in mean maximum active distance, possibly due to temperature effects upon male threshold. The active distance estimates were used to design an optimal monitoring trap deployment strategy to minimize attraction of males from areas surrounding orchards. Using Bossert and Wilson's equation for active space, the average lower (initiation) threshold for upwind flight was 7.2 × 10−17 g/cm3 and the upper (termination) threshold was 2.1 × 10−13 g/cm3. Their model should be altered so that active space is defined as the space where pheromone concentration is within both lower and upper thresholds for a particular behavio

DIEL PERIODICITY OF MALE SEX PHEROMONE RESPONSE AND FEMALE ATTRACTIVENESS IN THE GYPSY MOTH (LEPIDOPTERA: LYMANTRIIDAE)

In field studies gypsy moth males were attracted to synthetic cis-7,8-epoxy-2-methyloctadecane (disparlure), the female sex pheromone, and virgin females from 0900 to 2000 (Eastern Standard Time). The greatest numbers of males were lured to the synthetic attractant or the calling female from 1100 to 1500. These periods of male response are longer than reported in previous (1896 and 1932) New England investigations and suggest the possible recent evolution of a new diel rhythm of male sex pheromone respons

STUDIES OF PHYSIOLOGICALLY ACTIVE ARTHROPOD SECRETIONS: X. SEX PHEROMONE OF THE EASTERN SPRUCE BUDWORM, CHORISTONEURA FUMIFERANA (LEPIDOPTERA: TORTRICIDAE)

The sex pheromone of the female eastern spruce budworm was identified as trans-11-tetradecenal by a combination of electroantennogram techniques, laboratory bioassays, and chemical analysis. Subsequent field trapping showed that this compound is a potent attractant for both male Choristoneura fumiferana (Clem.) and C. occidentalis Free, thus supporting its identification as a sex pheromone of the eastern spruce budworm and suggesting that it is also a major component in the pheromone system of C. occidentali

A search for the hidden population of AM CVn binaries in the Sloan Digital Sky Survey

We present the latest results from a spectroscopic survey designed to uncover the hidden population of AM Canum Venaticorum (AM CVn) binaries in the photometric data base of the Sloan Digital Sky Survey (SDSS). We selected ∼2000 candidates based on their photometric colours, a relatively small sample which is expected to contain the majority of all AM CVn binaries in the SDSS (expected to be ∼50). We present two new candidate AM CVn binaries discovered using this strategy: SDSS J104325.08+563258.1 and SDSS J173047.59+554518.5. We also present spectra of 29 new cataclysmic variables, 23 DQ white dwarfs and 21 DZ white dwarfs discovered in this survey. The survey is now approximately 70 per cent complete, and the discovery of seven new AM CVn binaries indicates a lower space density than previously predicted. From the essentially complete g ≤ 19 sample, we derive an observed space density of (5 ± 3) × 10^(−7) pc^(−3); this is lower than previous estimates by a factor of 3. The sample has been cross-matched with the GALEX All-Sky Imaging Survey data base, and with Data Release 9 of the United Kingdom Infrared Telescope (UKIRT) Infrared Deep Sky Survey (UKIDSS). The addition of UV photometry allows new colour cuts to be applied, reducing the size of our sample to ∼1100 objects. Optimizing our follow-up should allow us to uncover the remaining AM CVn binaries present in the SDSS, providing the larger homogeneous sample required to more reliably estimate their space density