October 22, 2019

Traveler’s Tales of Gravitational Waves

We brake for gravitational waves…

(all photos by author)

This past week the science community held its breath, as rumors swirled once again that researchers had accomplished direct detection of gravitational waves. Sure, we’ve been down this road before, but with Advanced LIGO (the Laser Interferometer Gravitational-wave Observatory) resuming operation in late 2015, there’s good reason to believe said detection could come at any time. [Read more...]

Astro-Vid Of the Week: Watch the Full-Length LIGO Documentary

It’s not the Death Star… firing up the laser at LIGO.

Credit: NSF/LIGO, Used with permission.

It has arrived.

The search for gravitational waves is big news right now, and the hunt has heated up thanks to direct evidence for inflation in the early universe from the BICEP 2 project based in Antarctica.

But there’s another unique observatory on the hunt for gravity’s ghost: LIGO, or the Laser Interferometer Gravitational-wave Observatory. [Read more...]

15.05.10: A Speedy Binary.

Think that new Ducati in your garage is fast? Let me introduce you to HM Cancri. An unassuming +21 magnitude binary in the constellation Cancer, HM Cancri is comprised of two white dwarfs locked in a tight embrace. In fact, this binary system has the shortest orbital period known, handily knocking down distant contender V407 Vulpeculae with its “stately” 9.5 minute orbit. The facts are dizzying; the pair weigh in at 0.5 and 0.25 solar masses respectively, are about 24,000 miles apart (think geosynchronous orbit!) and revolve around each other in 5.4 minutes, about the time you hopefully spend glancing over this blog before returning to Facebook.  Get your calculators out; this makes orbital velocity for the pair an impressive 230 miles per second! Discovered in 1999, Observations using the Keck telescope have upheld HM Cancri’s record holding status by analyzing opposing spectral shifts of ionized helium as the two stars whirl about. This rules out other candidates such as a single neutron star.  Such a system must have had a very unique history, perhaps starting as a pair of Sun-like stars that later spiraled in. Will the two merge one day? Conservation of angular momentum cannot fully explain what we see as the system is speeding up; perhaps more accreting matter is present than we currently account for. The pair are approaching each other by about two feet per day, and of course, relativity comes into play in such an extreme system. Clearly, something interesting is occurring in this system. HM Cancri is also a strong x-ray source, and should generate copious amounts of gravity waves, especially in the event of a merger. Said waves may be within the realm of Advanced LIGO, due to come online in 2014, or LISA, ESA’s proposed Laser Interferometer Space Antenna. HM Cancri lies about 16,000 light years distant, and may be the strongest source of gravity waves in our galaxy.