THE SOUTHWORTH PLANETARIUM
70 Falmouth Street Portland, Maine 04103
43.6667° N 70.2667° W
Altitude: 10 feet below sea level
Founded January 1970
Julian Date: 24592546.18
2020-2021: LXXXVIII
THE DAILY ASTRONOMER
Thursday, February 11, 2021
Exploratorium XXI: The Cosmic Hand
Location
17,000 light years away
Time
17,000 years ago
Please....take another quick look.....
Did you see the "Cosmic Hand" also known as the "Hand of God.?"
Absolutely astounding, isn't it? Just when you thought that we couldn't do anything else to antagonize the University's council of the white, we decided to devote an entire DA to this most remarkable celestial object. We'll resist the temptation to assign a metaphysical significance to this discovery and stick solely to astronomy.
The "Hand of God" is only a quaint sobriquet designed to make the secularists seethe. The actual name is PSR B1509-58, a magnificent "pulsar wind nebula" located more than 17,000 light years away in the southern constellation Circinus.* Actually, PSR B1509-58 is just one object within that nebula and , ironically, isn't visible to us. Pulsars form after highly massive stars go supernova. Stars that are between 4 - 8 times more massive than the Sun produce pulsars after these explosions. (More massive stars create black holes.) This pulsar is actually a rapidly spinning neutron star, so named as its has two high energy radio lobes that appear to emit pulses when they sweep across our view. Compared to yesterday's millisecond pulsar that completes about 365 rotations per second, PSR B1509-58 is comparatively lazy, for it spins only seven times a second.
The pulsar is embedded within that "blue" glowing core deep within the nebula. The material we observe within this region consists of gases the original supernova violently expelled about 17000 years ago.** As the nebula spins, it pushes high energy rays into the surrounding magnetic field, resulting in the emission of x-rays. The image you saw on the link was not optical, but was instead captured by the Nuclear Spectroscopic Telescope Array (NuSTAR), an orbiting observatory that observes such objects in the X-ray EM spectrum. PSR B1509-58 was actually first discovered by the Chandra X-Ray Observatory in 2009.
In this image we observe not only the cloud's gradual but inexorable expansion related to the supernova explosion. We also see how the cloud reacts to and is energized by the pulsar shrouded within it. The pulsar 'heats' the nebula, inducing the energy emission. That much seems clear. What remains unresolved is the "hand." The nebula does seem to resemble an outstretched hand reaching from the pulsar toward an entirely separate reddish cloud named RCW 89. The fingers, incidentally, extend through 50 light years of space.
The question that remains unanswered pertains to these fingers. Has the nebula actually assumed a shape reminiscent of a human hand; or is it merely an optical illusion? Granted, addressing this issue will do little to resolve the controversy about its age (see second footnote) or the actual interplay of energy and matter within the cloud. What we will know, however, is whether or not an invisible hand large enough to encompass hundreds of star systems actually floats out there in the void.
Tell us that's an issue not worth exploring.
*I think this is the very first time we've happened upon this constellation. Invented by French astronomer Nicolas Louis de Lacaille (1713-1762), Circinus represents a compass well below our sight line. (One would have to venture below the Tropic of Cancer to see it.) This faint and small constellation resembles a thin triangle quite close to Alpha Centauri, the closest star to our solar system.
**Just an important side note: astronomers calculate a pulsar's age through the "spin down" rate. A pulsar's spin rate is greatest just after its formation, but then through time the rotation rate slows. This spin rate decrease varies with pulsars relative to the brake function. Based on the pulsar's rotation rate and mass, the supernova is believed to have occurred 1700 years ago. However, some researchers insist that the supernova nebula expansion rate and current size suggests the event occurred much earlier. The discrepancy has not yet been resolved, but we thought we'd mention it so as to point out that the 1700 year figure is not certain.
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