Astronomers Find 62-Minute Pulsar LPT J1555-5631, Then Lose It Again

Q: What mysterious object near the Milky Way's center is firing 62-minute radio bursts with a warped, non-dipole magnetic field?

It is **LPT J1555-5631**, a newly identified **long-period transient** near the Milky Way’s center. Astronomers found it in archival **MeerKAT** data and confirmed it with **ASKAP** observations of the same region. The source emits strong radio bursts on a highly regular **62.2-minute cycle**, making it part of a small but growing class of mysterious Galactic radio objects known as LPTs. What makes LPT J1555-5631 especially notable is that it produces **two radio pulses per cycle**, one longer and one shorter, with **opposite circular polarization**. That pattern suggests the emission likely comes from regions near **both magnetic poles** and that the object’s **rotation axis and magnetic axis are nearly perpendicular**. The key clue pointing to a warped or non-dipole magnetic field is the pulse spacing. If the object had a simple dipole field, the two pulses would be expected to be separated by **180 degrees**. Instead, they are separated by **165.4 degrees**, indicating a **more complex magnetic structure**. Astronomers still do not know what LPT J1555-5631 physically is. The leading explanations are a **slowly rotating neutron star**, such as a **pulsar or magnetar**, or possibly a **white dwarf in a binary system**. For now, LPT J1555-5631 is best described as an **enigmatic long-period transient** whose unusual timing and polarization offer one of the clearest new clues to the nature of this emerging class.

1 articles · Updated · ScienceAlert · Nov 14

Archival MeerKAT and 10-hour ASKAP data revealed LPT J1555-5631, a long-period transient that emitted powerful radio flares every 62.2 minutes in 2022 before going silent again.
Two pulses appeared in each cycle—one long, one short—with opposite circular polarization, pointing to emission from near both magnetic poles.
The pulses were separated by 165.4 degrees rather than 180, suggesting a more complex magnetic field than a simple dipolar neutron-star model.
Around a dozen LPTs have now been identified across the Milky Way, but astronomers still cannot tell whether they are unusual neutron stars, white dwarfs, or multiple kinds of objects.
The stop-start behavior remains a central mystery: most LPTs have not reappeared, though the 2002 source GCRT J1745-3009 and two others later became active again.