Unusual Stellar Phenomenia
(Editor's Note: Some of this is pretty convoluted. I took it from a Star Trek source guide, but this section seems to be a bit full of abstract astrological concepts instead of simplified statements or Star Trek jargon. Sorry.)
Antimatter Body
Although cosmologists believe that most of the Galaxy's original store of antimatter was annihilated early in the creation of the universe, clumps of antimatter might survive in the interstellar vacuum. Obviously, any normal matter such as starships or crew members coming into contact with an antimatter body would annihilate themselves; the antimatter body will emit gamma rays from such annihilations.
Black Hole
Stars of sufficient mass continue to collapse past neutron star stage into black holes, having gravity so intense (a hundred billion times Earth's gravity) that light cannot escape. An accumulated disk of dust, gas and radiation surrounds many black holes. As this matter falls into the black hole, gravity waves and powerful X-rays radiate outward, endangering starships or even nearby worlds. Moving into a black hole's gravity field runs the risk of a relativistic one-way trip up to a billion years into the future.
Cluster
A clump of stars close enough together (usually in the same sector) to remain mutually gravitationally influenced becomes a cluster. Most stars in a cluster are the same age. Some clusters, such as the Pleiades, contain thousands of stars. Planetary formation, high levels of radiation and gravitational anomalies (such as those in the Black Cluster) are among the interesting features of clusters.
Cosmic Strings
Incredibly long and incredibly dense, cosmic strings, or superstrings, may make up the majority of the dark matter in the Galaxy. A cosmic string resembles a black hole except it is one proton in diameter and light-years wide. Lost alien races might have used cosmic strings for cosmological engineering, or as unstoppable weapons since a single superstring could slice warships, planets or entire stars neatly in half.
Lazarus Star
Some supergiant stars survive their first supernova, expand again, then collapse into a second supernove. Nested shells of ionized gas surround these "Lazarus stars" in miniature nebulas. Any surviving planets or asteroids around these stars would be rich in heavy metals, radioactives and exotic compounds such as dilithium. Mining expeditions might prove worth the dangers such systems pose, especially in times of crisis. The Kavis Alpha neutron star is an amazingly regular and powerful Lazarus star, exploding every 196 years.
Nebula
Any large intersteller could of gas or dust can be called a nebula. Most nebulas result either from massive supernova explosions or from te emissions of protostars. Nebulas range from 1 to 200 light-years across. Many nebulas block Federation sensors and subspace radio signals. Some nebulas contain radioactive contaminants or energy fields that interfere with warp engines, computer systems, or even human metabolic processes. Some nebulas hold so much intersteller hydrogen and dust particles that they block starlight entirely. These "dark nebulas" make especially fertile grounds for star formation.
Plasma Field
In sectors where the space-time continuum is particularly unstable, the intersteller hydrogen often accumulates into dangerous plasma disruptions, discharing across parsecs in a shower of fiery energy. Wormholes may be associated with these phenomena. In some sectors (such as the Cardassian border Badlands) the plasma disruptions make up a continuous plasma field which becomes a grave hazard to navigation.
Pulsar
A rapidly-spinning neutron star emits a powerful pulse of energy (in any wavelength from radio to X-rays, including visible light) at a regular (although slowly increasing) rate as it spins, throwing off energy. Pulsar spin periods range from a millisecond to nearly five seconds. Star-faring races often use pulsars as navigational beacons because of their regularity and their relatively even spacing.
Quasar
Quasars are superbright objects several light-hours across, emitting more light that a hundred galaxies. Quasars are most likely the nearly-solid accumulated globe of light energy around a black hole the mass of a billion suns. Although 20th-century astronomers never located a quasar in our Galaxy, the U.S.S. Enterprise-D began charting the Merkoria Quasar in 2370, and the Federation has been studying the Murasaki 312 protoquasar near Taurus II since 2267. These quasars lie behind think veils of interstellar dark matter.
Rogue Planet
A rapidly-passing neutron star or black hole can easily rip a planet out of its orbit and send it spinning into interstellar space. Since rogue planets have no intrinsic light, detecting them in deep space is almost impossible. This makes rogue planets excellent locations for secret military bases or research labs.
T Tauri Star
Yellow stars pass through the T Tauri stage very early in their stellar evolution, losing much of their solar lithium and other light metals in a vast "T Tauri wind" blowing billions of kilometers into space. Although virtually all T Tauri stars are too young to have planets, the starship Enterprise-D discovered a rare Class M planet around a T Tauri star in the Ngame Nebula.
Temporal Rift
In many cases sufficient stress to the fabric of space in a sector can create a temporal rift. Depending on the circumstances, as little as a photon torpedo barrage can open a temporal rift. The vehicles of many time-traveling cultures create temporal rifts. When rifts fold upon themselves, causality loops, such as the one that trapped the U.S.S. Bozeman from 2278 to 2368, can form where time either does not pass at all or loops back upon itself so that the same minutes or hours repeat endlessly. Some temporal rifts, especially those associated with quantum fissures, wormholes, or ion storms, can also open gateways to parallel universes.
Variable Stars
Some stars alter their energy output, either their brightness, rotation, spectrography or surface change, in a relatively brief period of time (as short as days or even minutes). Cepheid variables release built-up stellar energy in a nova-like explosion. Flare stars simply shot out giant solar flares which might endanger a ship in orbit or burn some luckless planet to toast.
Wormhole
A wormhole is a subspace tunnel connecting two points in normal space-time. Wormholes can span tens of thousands of light-years, although they often prove unstable and fluctuate wildly. Warp engines can destabilize a wormhole, and a sufficiently unbalanced warp engine will occasionally create a dangerous micro-wormhole. Highly advanced races may create wormholes. The Bajoran Wormhole is one such artificial construct.