Tag Archives: radio astronomy

The magnetic field of a spiral galaxy

Magnetic field of a spiral galaxy
Click for full image.

Using a variety of telescopes, especially the Jansky Very Large Array radio telescope, astronomers have successfully mapped the magnetic field lines of a spiral galaxy seen edge on and 67 million light years away.

The image to the right, cropped and reduced to post here, shows what they have found.

The magnetic field lines extend as much as 22,500 light-years beyond the galaxy’s disk. Scientists know that magnetic fields play an important role in many processes, such as star formation, within galaxies. However, it is not fully understood how such huge magnetic fields are generated and maintained. A leading explanation, called the dynamo theory, suggests that magnetic fields are generated by the motion of plasma within the galaxy’s disk. Ideas about the cause of the kinds of large vertical extensions seen in this image are more speculative, and astronomers hope that further observations and more analysis will answer some of the outstanding questions.

Our understanding of these kinds of gigantic magnetic fields is poor, to put it mildly. This data really only begins the research.

China’s FAST radio telescope discovers 93 new pulsars

The research team running China’s FAST radio telescope, the largest single dish such telescope in the world, have announced that they have discovered 93 new pulsars since October 2017.

China might still be having trouble finding a big name astronomer to run the telescope, but in the meantime it looks like their own people are taking advantage of the situation to use the telescope establish their own names.

Arecibo gets $12.3 million NSF grant

The National Science Foundation has awarded the Arecibo radio telescope in Puerto Rica a $12.3 million grant to pay for needed repairs and upgrades following the hurricane damage from 2017.

The money will pay for the following work:

  • Repairing one of the suspension cables holding the primary telescope platform, ensuring long-term structural integrity of one of the main structural elements of the telescope.
  • Recalibrating the primary reflector, which will restore the observatory’s sensitivity at higher frequencies.
  • Aligning the Gregorian Reflector, improving current calibration and pointing.
  • Installing a new control system for S band radar, which is part of the microwave band of the electromagnetic spectrum.
  • Replacing the modulator on the 430 MHz transmitter, increasing consistency of power output and data quality.
  • Improving the telescope’s pointing controls and data tracking systems.

Most of this looks to be very basic maintenance, which suggests the telescope is still very starved for funds.

Fast radio bursts not detected at certain radio wavelengths

In observations by two different radio telescopes operating at different radio wavelengths but looking at the same part of the sky, astronomers have found that an observed fast radio burst was not detected by one of those telescopes.

The Curtin University-led Murchison Widefield Array (MWA) and CSIRO’s Australian SKA Pathfinder (ASKAP) telescopes were searching the sky for fast radio bursts, which are exceptionally bright flashes of energy coming from deep space. These extreme events last for only a millisecond but are so bright that many astronomers initially dismissed the first recorded fast radio burst as an observational error.

In research published in the Astrophysical Journal Letters, astronomers describe how ASKAP detected several extremely bright fast radio bursts, but the MWA—which scans the sky at lower frequencies—did not see anything, even though it was pointed at the same area of sky at the same time.

Lead author Dr Marcin Sokolowski, from the Curtin University node of the International Centre for Radio Astronomy Research (ICRAR), said the fact that the fast radio bursts were not observed at lower frequencies was highly significant. “When ASKAP sees these extremely bright events and the MWA doesn’t, that tells us something really unexpected is going on; either fast radio burst sources don’t emit at low frequencies, or the signals are blocked on their way to Earth,” Dr Sokolowski said.

If blocked at these lower frequencies, this tells theorists something about the environment where the burst occurred. If instead the burst does not emit in those lower frequencies, it tells them something about the burst itself.

Radio telescope in Greenland sees first “light”

Astronomers have successfully initiated operations of a new radio telescope dish, the first ever located in Greenland.

The Greenland Telescope is a 12-meter radio antenna that was originally built as a prototype for the Atacama Large Millimeter/submillimeter Array (ALMA) North America. Once ALMA was operational in Chile, the telescope was repurposed to Greenland to take advantage of the near-ideal conditions of the Arctic to study the Universe at specific radio frequencies, collaborating with the National Radio Astronomy Observatory (NRAO) and MIT Haystack Observatory.

ASIAA led the effort to refurbish and rebuild the antenna to prepare it for the cold climate of Greenland’s ice sheet. In 2016, the telescope was shipped to the Thule Air Base in Greenland, 1,200 km inside the Arctic Circle, where it was reassembled at this coastal site. ASIAA also built receivers for the antenna. “It is extremely challenging to quickly and successfully set up a new telescope in such a cold environment, where temperatures fall below -30 degrees Celsius,” said Ming-Tang Chen from ASIAA and the Greenland Telescope project manager. “This is now one of the closest radio telescopes to the North Pole.”

They have also linked this radio telescope to others across the globe, helping to increase the resolution of any data these radio telescopes gather as a unit.

First results from Breakthrough Listen’s search for alien radio signals

Breakthrough Listen has released its first results from its search for extraterrestrial radio signals using the Greenbank Observatory in West Virginia.

Breakthrough Listen – the initiative to find signs of intelligent life in the universe – has released its 11 events ranked highest for significance as well as summary data analysis results. It is considered unlikely that any of these signals originate from artificial extraterrestrial sources, but the search continues. Further, Listen has submitted for publication (available April 20) in a leading astrophysics journal the analysis of 692 stars, comprising all spectral types, observed during its first year of observations with the Green Bank Telescope.

The press release tries to make a big deal about this data, but essentially what it boils down to is that so far they have found nothing that could indicate artificial radio signals coming from any of these stars.

The National Radio Astronomy Observatory (NRAO) has renamed the thirty-one year old Very Large Array (VLA) after Karl Jansky, the man who invented radio astronomy.

A fitting honor: The National Radio Astronomy Observatory (NRAO) has renamed the recently upgraded thirty-one year old Very Large Array (VLA) after Karl Jansky, the man who invented radio astronomy.

Karl Guthe Jansky joined Bell Telephone Laboratories in New Jersey in 1928, immediately after receiving his undergraduate degree in physics. He was assigned the task of studying radio waves that interfered with the recently-opened transatlantic radiotelephone service. After designing and building advanced, specialized equipment, he made observations over the entire year of 1932 that allowed him to identify thunderstorms as major sources of radio interference, along with a much weaker, unidentified radio source. Careful study of this “strange hiss-type static” led to the conclusion that the radio waves originated from beyond our Solar System, and indeed came from the center of our Milky Way Galaxy.

His discovery was reported on the front page of the New York Times on May 5, 1933, and published in professional journals. Jansky thus opened an entirely new “window” on the Universe. Astronomers previously had been confined to observing those wavelengths of light that our eyes can see. “This discovery was like suddenly being able to see green light for the first time when we could only see blue before,” said Lo.