Question: When should stars grow closer to each other?
About the article "Gravitational wave", section "Radiation from other sources".

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Sweet Revenge is a 2001 British television film that aired in two parts on BBC One on 15 and 16 October 2001.
It stars Sophie Okonedo, Paul McGann and Pam Ferris.
Written by Sandy Welch and directed by David Morrissey, "Sweet Revenge" tells the story of a group of wronged Londoners who seek to exact revenge upon those who have mistreated them.
Each employs the enigmatic Professor Patrick Vine, (McGann), who, when not teaching History and Anthropology, runs a sideline in helping people get revenge.
The story centres upon Ellen, (Okonedo), who is seeking revenge on her cheating husband.
As the plot progresses, she and Vine grow closer. 
When the partial remains of nature photographer Cliff Benson are found in the woods near Hyde River, his brother, Steve, investigates the mysterious attack.
After finding problems with a theory involving a bear attack, he teams up with local sheriff's deputy Tracy Ellis.
As the deaths continue and the townsfolk are pressed for information, they close ranks, under the mysterious "Oath" made when the town was founded.
Steve and Tracy grow closer to each other as they peel away the mystery and come face to face with the dark evil behind the deaths. 
Some of the most prosperous forms of life at the Davenport Tide Pools are Sea Stars.
This is due to the rifts and ridges up and down the tide pools, these allow Sea Stars to move father up the Tidal zone.
Normally Sea Stars are subtidal organisms that live closer to the ocean, because they die when they become too dry.
Their prey are Mussels that live up and down the tidal zone, since their hard shells allow them to live in drier areas for longer.
The rifts and ridges at the Davenport Tide pools allow the Sea Stars to feed off of Mussels at higher tidal zones during lower tides.
Since the Mussels are only a few inches above a rift that is level with the subtidal zone.
Other Tide Pool life include many species of Mussels, Limpets, Seaweed, barnacles, and surf grass.
These organisms are also affected by the geographical features of the tide pools.
The seaweed and surf grass are able to grow father up the tidal zones.
Many sea stars have adapted to hide under the seaweed and surf, as a way to not dry out.
This than allows them to feed on the various higher tidal zone organisms during high tide.
The main diet of the Sea Star in Northern California is Mussels Since Davenport Tide Pools has an abundance of Mussels, Sea Stars do not resort to consuming other less desirable organisms. 
Although the waves from the Earth-Sun system are minuscule, astronomers can point to other sources for which the radiation should be substantial.
One important example is the Hulse-Taylor binary — a pair of stars, one of which is a pulsar.
The characteristics of their orbit can be deduced from the Doppler shifting of radio signals given off by the pulsar.
Each of the stars has a mass about 1.4 times that of the Sun and the size of their orbit is about 1/75 of the Earth-Sun orbit.
This means the distance between the two stars is just a few times larger than the diameter of our own Sun.
The combination of greater masses and smaller separation means that the energy given off by the Hulse-Taylor binary will be far greater than the energy given off by the Earth-Sun system — roughly 1022 times as much.
The information about the orbit can be used to predict just how much energy (and angular momentum) should be given off in the form of gravitational waves.
As the energy is carried off, the stars should draw closer to each other.
This effect is called an inspiral, and it can be observed in the pulsar's signals.
The measurements on the Hulse-Taylor system have been carried out over more than 30 years.
It has been shown that the gravitational radiation predicted by general relativity allows these observations to be matched within 0.2 percent.
In 1993, Russell Hulse and Joe Taylor were awarded the Nobel Prize in Physics for this work, which was the first indirect evidence for gravitational waves.
Unfortunately, the orbital lifetime of this binary system before merger is about 1.84 billion years.
This is a substantial fraction of the age of the universe.
Inspirals are very important sources of gravitational waves.
Any time two compact objects (white dwarfs, neutron stars, or black holes) are in close orbits, they send out intense gravitational waves.
As they spiral closer to each other, these waves become more intense.
At some point they should become so intense that direct detection by their effect on objects on Earth or in space is possible.
This direct detection is the goal of several large scale experiments.
The only difficulty is that most systems like the Hulse-Taylor binary are so far away.
The amplitude of waves given off by the Hulse-Taylor binary as seen on Earth would be roughly "h" ≈ 10−26.
There are some sources, however, that astrophysicists expect to find with much larger amplitudes of "h" ≈ 10−20.
At least eight other binary pulsars have been discovered.
The stack area contains the program stack, a LIFO structure, typically located in the higher parts of memory.
A "stack pointer" register tracks the top of the stack; it is adjusted each time a value is "pushed" onto the stack.
The set of values pushed for one function call is termed a "stack frame".
A stack frame consists at minimum of a return address.
Automatic variables are also allocated on the stack.
The stack area traditionally adjoined the heap area and they grew towards each other; when the stack pointer met the heap pointer, free memory was exhausted.
With large address spaces and virtual memory techniques they tend to be placed more freely, but they still typically grow in opposite directions.
On the standard PC x86 architecture the stack grows toward address zero, meaning that more recent items, deeper in the call chain, are at numerically lower addresses and closer to the heap.
On some other architectures it grows the opposite direction.