OUT THERE 



Cosmic Cosmetics 



Astronomers havejomid lots of nail-polisli remover 

 and sunless tanning lotion in space. 



By Charles Liu 



Its Earth-year 6526 and you 

 find yourself cruising inter- 

 stellar space. But — drat! — 

 your nail polish is chipped. And 

 how will you ever restore your 

 earthy, bronze-goddess glow so 

 far from the tanning light of any 

 sunlike star? Great Hubble's 

 ghost, what's a person to do?! 

 My futuristic scenario is, ot 

 course, a space-age joke, but 

 your distress would be short- 

 lived: Drugstore beaury prod- 

 ucts really cio float around in 

 space, sort of, and recent 

 observations by two teams 

 of astronomers — one led 

 by Douglas N. Friedel, 

 the other by Susanna L. 

 Widicus Weaver, both 

 at the University of 

 Illinois at Urbana— 

 Champaign — suggest 

 that you won't have 

 to comb the cosmos 

 for such beauty aids. 

 Nail polish remover — 

 acetone — just what 

 you need before you re- 

 paint your nails, is pre- 

 sent in abundance, along 

 with its distant chemical 

 cousin 1 ,3-dihydroxyacetone 

 (DHA), the active ingredient in sun- 

 less tanning lotion. The two chemicals 

 have been detected before now, but the 

 new work shows that plenty ot both are 

 suspended in the vast clouds of gas and 

 dust that surround newly formed stars. 



At first blush, the detection of large 

 amounts of interstellar acetone and 

 DHA may seem like nothing more than 

 amusing curiosities. Actually, finding 



any complex molecule is serious sci- 

 ence, and organic compounds such as 

 acetone and DHA pose a special inter- 

 est. Learning how much of each spe- 

 cies is out there, as well as where they 

 can be found, may be important for un- 

 derstanding the origins of life. 



Astrochemists have detected more 

 than 130 molecular species over 

 the years, including alcohol, antilreeze, 

 various hydrocarbons, and even sugar 

 and salt. In spite of the numbers, find- 

 ing molecules in space is very hard work. 



Normally when a gas glows, the 

 glow signals that the gas has been heat- 

 ed, perhaps by a nearby star, perhaps by 

 the gravitational collapse of the cloud 

 of gas itself. When gas particles are heat- 

 ed, they typically absorb energy from 

 their surroundings, then re-emit it as 

 light in a spectrum of distinct colors, or 

 wavelengths, that is characteristic of the 

 gas and identifiable by astronomers. 



Unfortunately, though, interstellar 

 nebulae, particularly the ones that har- 

 bor molecules, can include dozens or 

 even hundreds of different kinds of 

 gas particles. So sorting through their 

 combined, overlapping spectra to 

 identify one kind of molecule is a lit- 

 tle like picking out a single fin- 

 gerprint on a subway turnstile 

 after rush hour. 



As if that weren't chal- 

 lenging enough, the more 

 complicateci the gas particles 

 are, in general, the more com- 

 plicated the spectra they emit. 

 The simplest spectra are emit- 

 ted by atoms. Hydrogen and 

 helium, the simplest atoms, pro- 

 duce clearly identifiable emission ^ 



peaks in their spectra, making them 

 relatively easy to distinguish. As soon 

 as you stick two or more atoms to- 

 gether in a molecule, though, things 

 get ugly. Unlike the rigid wooden balls 

 and dowels of college organic chem- 

 istry sets, real molecules are more like 

 marshmallows attached to each other 

 with Slinkies — they flip, flop, roll, 

 spin, squish, and vibrate, and every ac- 

 tion leads to its own characteristic 

 emission color. 



For those reasons, the spectra of ace- 

 tone and DHA are very complex in- 

 deed. The acetone molecule is made 

 up of ten atoms, and DHA is made up 

 of twelve. Their combined motions 

 give rise to spectra with thousands of 

 emission peaks — some isolated and 

 narrow, others mushed together in 

 broad bands of color. Even "color" is a 

 bit of a misnomer; most molecules, in- 

 cluding acetone and DHA, emit spec- 

 tra at wavelengths of just a few inilli- 

 meters — that is, microwaves and radio 

 waves, invisible to the human eye. 



With the recently retired, multi- 

 antenna interferometric observ- 

 atory of the Berkeley— Illinois— Maryland 

 Association at Hat Creek, California, 

 Friedel's team found interstellar acetone 

 in the hot gaseous core of the Orion— KL 

 region. The site, 1,500 light-years from 

 Earth, is a nursery for massive stars. 

 Meanwhile, at the 10.4-meter single- 

 dish Caltech SubmiUimeter Observa- 

 toi"y on Mauna Kea, Hawai'i, Widicus 

 Weaver, along with Geoffrey A. Blake 

 of Caltech, targeted another site of 

 massive star formation. There, in 

 another hot, gaseous core of a 

 region called Sagittarius B2 

 ^ (N-LMH), about 26,000 

 light-years from Earth, 

 they identified DHA. 

 Both clouds are rich 



Geoffrey Wowk, 

 Cosmopolishing, 

 2005 



58 



NATURAl, HisioKY February 2006 



