The Johns Hopkins Gazette: March 22, 1999
Mar. 22, 1999
VOL. 28, NO. 27


Scene On Campus

Noon, Wednesday, Jan. 19, Homewood

Johns Hopkins Gazette Online Edition

William Blake perceived the world in a grain of sand and heaven in a wildflower.

So do astronomers at Bloomberg hear galactic jets spewing in the tangy spritz of a tangerine and see the inexhaustible hunger of a black hole as the department chairman devours his chicken sandwich?

And what can be made of all the crunching and slurping among graduate students tippling sodas along the rim of the conference table?

The regular Wednesday lunch in the basement of the Bloomberg building attracts a bright assortment of faculty and students, where mentors and their brood present the latest in astronomical research and square off.

It is no poetry reading.

Today's wrangle begins with a toss-up.

The question: For $180 million, NASA has launched the Stardust spacecraft to scoop icy dust grains out of the tail of a comet using a new material called aerogel--what is aerogel?

"You know, during re-entry, that spacecraft will get pretty warm," observes Paul Feldman, chairman of Physics and Astronomy. "How will they know they've preserved the grains and kept them cold?"

"They'll know when they open it up and it's wet on the inside," someone quips.

Bill Blair, a research scientist for the FUSE mission, pretends to open a spacecraft and sneezes the contents all across the room.

After the laughter subsides, someone defines aerogel as a kind of glass that's 99 percent air--space-age supermaterial.

"But will the CO2 dissolve before it gets back to Earth?" Feldman asks.

The chairman hushes the room with that one, and finishes his sandwich amid puzzled sighs.

Postdoc Ravi Sankrit makes the day's presentation, shuffling through a flurry of viewgraphs and asking everyone to contemplate a Lyman Alpha emission line of -82 km/s-1.

"It is a complicated-looking beast," he says, referring to an ionized disk found inside galaxy M87. Only five years ago, one of the department's distinguished faculty members, Holland Ford, found conclusive evidence of a black hole in the center of the elliptical galaxy. On Feb. 27, 1994, Ford had been astounded to see images of M87 taken with the Hubble Telescope suggesting that an enormous disk of hot ionized gas was swirling at tremendous speeds around an extremely massive, extraordinarily compact object.

Now, Sankrit has a small collection of Hubble spectra taken over a five-day period showing a continuous flash and shock wave blistering off the edge of the disk, as it spins at 1300 km/sec.

Faculty and students pepper him with questions as he winds through a series of spectrographs and charts.

"What's the resolution of that data?" one demands.

"Is the evidence of carbon 4 due to some kind of shocks or to photo-ionization?"

Sankrit picks through a pile of spectra and charts like a dealer at a Vegas casino, offering data analysis that silences the room. Dressed in a pair of faded blue jeans, he has that bedraggled postdoc look in his eyes, which says he will no longer truck with the annoying contrivance of gamesters in the room.

"When I first saw this sequence of images," he says, "I was very excited. But, as you have pointed out, it was easy to have that enthusiasm chilled by positioning errors."

Another whirl of questions comes without invitation, and research scientist Ken Sembach, who hosts these weekly affairs, must step in to keep things rolling.

"Ravi, why don't you go ahead, and we'll ask questions later?"

"Well, that was the idea," Sankrit agrees.

So was it simply positioning error in the data that made it appear that something wonderfully cataclysmic had occurred in M87? Or was there a more exciting possibility?

"The data call for interpretation," Sankrit says.

He pauses, and smiles.

It very well could be that during this five-day period a star was dragged into the black hole, he says matter-of-factly. He points to evidence of a brilliant, luminous, gaseous gush.

Everyone in the room seems entranced. Sankrit has them in his grasp.

"But," he teases, "we don't really know."

A small mystery of the universe sends Bloomberg's astronomers shuffling back to their offices and another afternoon of ever-greater enticements, leaving behind a conference room tinged with the homey smells of chicken broth and stewed vegetables.
--Gary Dorsey