When you depict the solar system in your mind, most people think of the sun standing still in the center and standing still, surrounded by other things. However, each star in the solar system also exerts its own gravity on the star, causing the star to move a little.
Therefore, the precise center of gravity (or center of gravity) of the solar system does not explode suddenly in the middle of the sun, but is closer to the surface of the sun, that is, outside the sun. However, due to numerous gravitational effects, it is difficult for us to figure out the exact location of this center of gravity.
Now, using specially designed software, an international team of astronomers has reduced the location of the center of gravity of the solar system to within 100 meters (328 feet)-it will greatly improve our measurement of gravity waves.
This is all related to pulsars. These dead stars can spin extremely quickly in milliseconds, emitting electromagnetic radiation beams from both poles. If they are in the right direction, these beams flash over the earth like extremely fast cosmic lighthouses, generating extremely regular pulse signals.
From detecting interstellar media to potential navigation systems, this regular pulse is useful for all kinds of things.
In recent years, observatories including the NANO Gravity Observatory (NANOGrav) have used them to find low-frequency gravitational waves because gravitational waves cause a very slight disturbance when they are arranged in a series of pulsars in the entire sky.
Astronomer and physicist Stephen Taylor of Vanderbilt University and “NANOGrav Collaborative Organization” explained: “Using the pulsars we observed in the Milky Way, we try to sit still like a spider. In the middle of the net.”
“Our understanding of the center of gravity of the solar system is critical, because we try to even perceive the smallest sting on the network.”
That’s because the error in the calculation of the position of the earth relative to the center of gravity of the solar system will affect our measurement of pulsar timing, which in turn will affect our search for low-frequency gravitational waves.
Part of the problem is Jupiter. To a large extent, it has the strongest gravitational effect on the sun-compared to tug boats of other planets for a few minutes. We know how long it will take Jupiter to orbit the Sun-about 12 Earth years-but our understanding of this orbit is not yet complete.
Previously, the estimation of the location of the center of gravity relied on Doppler tracking-how light from objects changes when we (or our instruments) move toward or away from them-to calculate the planet’s orbit and mass. However, any errors in these masses and orbits may introduce errors that look much like gravity waves.
Moreover, when the team used these existing data sets to analyze NANOGrav data, they had been getting inconsistent results.
Astronomer Michele Vallisneri of NASA’s Jet Propulsion Laboratory said: “In the gravitational wave search between the solar system models, we did not find anything important, but there were huge differences in the system in the calculation.”
“Normally, more data can provide more accurate results, but our calculations are always biased.”
This is where the team software enters the picture. It’s called the Bayesian Nebula (BayesEphem), and it aims to model and correct those uncertainties in the solar system’s orbit that are most relevant to gravitational wave searches using pulsars, especially Jupiter.
When the team applied BayesEphem to NANOGrav data, they were able to set new limits for gravity wave background and detection statistics. They were able to calculate a new, more accurate position for the center of gravity of the solar system, thus enabling more accurate low-frequency gravity wave detection.
Taylor said: “Our accurate observations of pulsars scattered in galaxies are better than ever before to position ourselves in the universe.”
“Finding gravitational waves in this way, in addition to conducting other experiments, we also obtained a more comprehensive overview of all the different types of black holes in the universe.”
The study has been published on Astrophysical Journal.