Infrared Observations of $\beta$ Pictoris Analogs
Session 32 -- Circumstellar Environments
Oral presentation, Wednesday, January 12, 2:15-3:45, Salon VI Room (Crystal Gateway)

## [32.01] Infrared Observations of $\beta$ Pictoris Analogs

S.B. Fajardo-Acosta (SUNY Stony Brook), R.F. Knacke (Penn State Erie), C.M. Telesco (NASA MSFC)

We searched for 10 $\mu$m silicate emission from circumstellar dust in 13 main-sequence stars that possibly exemplify the $\beta$ Pictoris phenomenon. We have previously detected the silicate feature in 51 Oph (Fajardo-Acosta, Telesco, \& Knacke 1993, ApJ, in press) through mid-IR narrowband spectrophotometry (FWHM $\approx$ 1 $\mu$m) with the MSFC Big Mac camera and the 2--30 $\mu$m Facility bolometer at the IRTF. We are using the same instrumentation in our survey of other Vega-type disks. These observations were motivated by the detection of the silicate feature in $\beta$ Pic (Telesco \& Knacke 1991, ApJ, {\bf 372}, L29). We followed the detections in $\beta$ Pic and 51 Oph with 2.9--13.5 $\mu$m intermediate-resolution ($\lambda/\Delta\lambda \approx$ 50) spectroscopy with the Aerospace Corp.\ Infrared Spectrograph. The higher resolution data confirmed the analogy of the silicate features in $\beta$ Pic (Knacke et al.\ 1993, ApJ, in press) and 51 Oph (Russell et al.\ 1993, in prep.) to similar features in Solar System cometary spectra.

Among the Vega-type stars we recently observed, $\beta$ UMa, $\zeta$ Lep, $\sigma$ Her, and $\gamma$ Oph exhibit significant dust emission at 10 $\mu$m ($\geq$ 0.15 Jy). We expect to resolve whether silicate emission is present with the higher spectral resolution available with the Aerospace Spectrograph.

We have compared the spectrum of $\beta$ Pic with those in the data compilation of the IRAS Low Resolution Spectrograph. Of the 5425 sources, 88 exhibit 10 $\mu$m silicate emission features that match $\beta$ Pic's reasonably well. Many of these sources do not have known associations; those that do are typically low-mass giant branch Miras or massive supergiants. We are investigating at least 5 possible associations with early-type main-sequence stars.

This research was sponsored by the NASA Origins of Solar Systems Research Program under grant NAGW-2334.