Austin, TX UT-Austin graduate student Feng Ma
didn’t expect to see a black hole gobble up a star when
he went out to McDonald Observatory to point a
telescope at the next quasar on the list of about 60
he’s studying. But that’s what happened, he realized
on later review of his observations of a quasar called
TEX 1726+344 with the 2.7-meter Harlan J. Smith Telescope.

Quasars are extremely bright pinpoints of light so
distant in space and time that it’s thought we’re seeing
them near the beginning of the universe. They are very
young galaxies, with giant black holes at their cores.
As material spirals around a black hole, it heats up
before falling in, giving off massive amounts of radiation.

Astronomers study this radiation by passing it through
a slit and spreading it into its component wavelengths,
just as light is passed through a prism to create a
rainbow. They can tease out which elements are present
in the jet streaming out of the galaxy’s core by seeing
the patterns of so-called “emission lines” in the quasar’s
spectrum. Ma has been studying quasars to see how their
emission lines may have changed over the last decade.

But in looking at his spectrum of TEX 1726+344, Ma saw
a feature that was not in spectra of the quasar made in
1988 and 1990: an “absorption line.” The presence of this
line indicates a cloud of material along our line of sight,
that is, in between the quasar’s high-energy jet and Earth.
This cloud is absorbing certain wavelengths of light coming
from the quasar.

The relative positions of the emission lines and the
absorption line on the spectrum show that this cloud is
being ejected from the black hole at 6,000 kilometers
per second, Ma said. “This leads me to think it’s the
signature of a star that’s been ripped apart by the black
hole’s gravity,” he said. “Half of the star’s matter fell into
the black hole, and the other half was ejected in a
gravitational sling-shot. This second half is the fast-moving
cloud that caused the absorption line.

“If this interpretation is correct, we could see this feature
in the spectrum go away in the next few years. I’d like to
keep an eye on this quasar to see what happens,” Ma said.

Ma’s research is published in this month’s issue of Monthly
Notices of the Royal Astronomical Society.

TEX 1726+344 was discovered as part of the Texas Radio
Survey (1974-1983), led by University of Texas astronomer
James Douglas and carried out with the now-defunct Texas
Interferomter radio telescope. UT-Austin graduate student
Elizabeth Bozyan identified TEX 1726+344 as a quasar in
her 1985 doctoral dissertation.

Feng Ma can be reached via email at: feng@astro.as.utexas.edu,
or by phone at: 512-471-3644.