Observation of a sun like star, what are the general observable properties of a star

Electromagnetic spectrum observations, magnitude brightness and luminosity, position, motion, spectroscopy。The details are as follows:

1. Electromagnetic spectrum observation.

Modern astronomers study stars, and the main source of information is electromagnetic radiation from stars. To date, electromagnetic radiation remains the most important source of information about stars (other than the Sun).

2. Magnitude, brightness, luminosity.

The brightness of a star is called apparent brightness. If the brightness of two stars differs by a factor of 100, then their apparent magnitude is 5 magnitude apart, which is very subordinated to the physiological sensation of the human eye. Stars vary widely, with some being brighter than magnitude 0 and others being faint.

The limit of magnitude that the human eye can see is generally equal, while with the help of large telescopes and electronic eyepieces, stars below magnitude 20 can be seen.

3. Stellar position measurement.

To determine the position of a star on Earth, it is only necessary to determine its coordinates on the celestial sphere and its distance from Earth. To determine the coordinates of a star on the celestial sphere, it is usually necessary to specify the celestial coordinates. Generally, there are horizon coordinate system, equatorial coordinate system, ecliptic coordinate system and galactic coordinate system.

All celestial coordinate systems specify the cardinal axes, cardinal points, and ranges of metric directions.

4. Stellar motion measurement.

The motion of stars in three-dimensional space requires three parameters to describe. The motion in the direction of the line of sight is called the radial velocity; Motion in the plane perpendicular to the line of sight (celestial sphere) is called self-determination. Due to the distance, the self-motion of the star can be considered as a uniform linear motion, and the unit is taken in angular seconds years.

The magnitude of the self value is obviously related to the proximity of the star.

5. Spectroscopy.

The difference in the color of stars is the proportion of wavelengths of their radiation. Refraction occurs when radiation passes through a medium, and the refractive index varies depending on the frequency.

Canonical naming

In the same year, the German astronomer Johann Bayer created the Bayer nomenclature, which combines the Greek alphabet sequence with the constellations, to name each star in the constellation. Then the English astronomer John Franstede invented the Fransteid nomenclature based on the right ascension values. The Byaer nomenclature is based on the brightness of each star in the constellation, arranged in Greek alphabetical order.

2. Another nomenclature of stars is the star catalog nomenclature, which is compiled by astronomers based on the observation data system. For example, the Bonn Catalog, the HD Catalog, the Hippars Catalog, the SAO Catalog, the Variable Star Catalog, the New Nebula Cluster Catalog, the Messier Catalog, the Orwells Elementary Catalog, and so on.

They classify different stars (or galaxies) into categories, and they are detailed in content, and the number of stars is large, which greatly facilitates the study of astronomy.

The above content refers to Encyclopedia - Stars.

Suppose someone is on the surface of the Earth and at position 1 and sees the Sun due south (i.e., 12 noon there) and there is a star far behind the Sun that is also due south (although the person can't see it). "A day later", when the Earth orbits to position 2, the Earth rotates exactly once, and the stars in the extreme distance still return to the south of this place, but because the Earth is rotating at the same time, the Earth has left position 1 and advanced to position 2, at this time, although the Earth has rotated for a circle, the Sun does not return to the south of the Earth, but slightly deviates to the southeast, and the Sun needs to go through a few more minutes to reach due south.

Sidereal day: The time interval between two consecutive sights of a very distant star in the same direction at a location on Earth.

Solar day: The time interval between two consecutive sights of the Sun in the same direction (e.g., due south) at a certain point on Earth.

In other words, the sidereal day is the true rotation period of the Earth, and the length of the sidereal day is 23 hours, 56 minutes and 4 seconds. The solar day is the unit of length of time we usually use: a day, or 24 hours.

Definition: The interval between two consecutive passes of the same meridian circle at the equinox. That is, the exact day.

The straight line obtained by connecting two points due south and north of a place is the meridian, and the plane determined by the meridian and the plumb line is the meridian in the direction of due south and north. The time interval between two opposite directions of the astronomical meridian of a certain place to the same star is called a sidereal day, and a sidereal day is the period of the Earth's rotation with the star as a reference.

The actual time it takes for the Earth to rotate once, or the time it takes for the equinox to pass through the same meridian twice, that is, the time it takes for a star to pass through the same meridian twice. One sidereal day is equal to 23 hours, 56 minutes and 4 seconds. In astronomy, it is not the specific stars that define the sidereal day, but the ascending node of the ecliptic to the celestial equator, that is, the first point of the Aries, which is the vernal equinox in the northern hemisphere.

However, the vernal equinox is constantly moving westward (precession), so there is still a difference between the sidereal day and the solar day in astronomy.

I searched for a long time to find it, and the last number was the distance, but the age was not found. Pick a star that's less than 40 light-years away.

Sun apparent magnitude

no Name English Star Plum Code Oak Name Constellation Apparent Magnitude Distance (light years) 1 Sirius Sirius Canis Major.

2 Old Man Canopus 803 South Gate II Rigel Kentaurus Centauri 4 Arcturus 305 Vega Lyra 25

6 Five rooks two capella Auriga 407 Betelgeuse seven rigel Orion 700

8 Procyon 119 Achernar 8010 Betelgeuse Orion 50011 Hadar Centauri 33012 Altair Aquila 1613 Acrux South Cross 45014 Aldebaran Taurus 6015 Antares Antares 50016 Spica Virgo 35017 North River 3 Pollux Gemini 3518 North Fall Master Fomalhaut South Fish 22

The gliese Nearstar Compliment Catalog may be of some help to you, at the address.

Don't dislike the English version, if you don't pay, you won't get anything back.

LS, you put a bright star in the first class of bright stars for fart use, how can a sun-like star within 40 light years be a bright star.

Be similar to the day fixed star: This refers to a star that resembles the Sun and has a planetary system. Mankind's observation of the universe is getting deeper and farther, and it is found that more and more extrasolar planets are leaking. In this case, many people wonder to what extent the solar system we live in is representative.

A new study shows that the structure of the solar system is extremely rare.

Hubble telescopes photographed Sirius and its companion** There is a long history of human observation of stars. Ancient Egypt used the appearance of Sirius on the eastern horizon to herald the day when the Nile River would flood. The Shang Dynasty of China set up a special ** to observe the appearance of fires in the east, and determine the time of the beginning of the year, which was listed in the divination along with the sowing and harvesting of crops.

The navigators of the Ming Dynasty in China used the Nine Stars of Navigation to determine the direction. The U.S. Apollo 11 spacecraft has an optical locator that uses stars to determine position.

The volume of a star can be measured by interferometry and lunar occultation to determine the angular diameter of the star, and thus the volume.

The mass of a star can be measured using Kepler's third law or the relationship between stellar luminosity and mass.

Stars age and expand into red giants swallowing orbital planets: or the future home of the Earth.

On August 24, 2012, an international research team composed of scientists from the United States, Poland and Spain found for the first time evidence that aging stars have engulfed their planets.

Sidereal day, because the sun is an unchanging star, maybe every day is a sidereal day of the sun, right?

The concept of the Earth's revolution produces years.

The concept of the Earth's rotation generating the day.

Due to the different frame of reference, there are sidereal days and solar days. In fact, both kinds of days are rotation + revolution angles. Since the reference frame of the sidereal day is very far away, the distance is recorded in light years, so the diameter of the Earth's revolution is about 300 million km, which is negligible for distant stars, so the sidereal day only has the Earth's rotation angle.

And the solar day is the angle of rotation of the earth + the angle of revolution of the earth.

The drawing method of the solar day and sidereal day in the college textbook "Introduction to the Earth" does not conform to the mathematical principle and is wrong! According to the two times of the solar day and the star, there are two times for the orbit of the earth, which misleads the students! It's ridiculous!

To put it simply.

Sidereal day: The time it takes to observe the star to return to its original position twice.

Solar day: The time it takes to observe the sun returning to its original position twice.

There is a difference between the two. After the Earth rotates about 366 times, it actually rotates the Sun once in one revolution, so we will only see the Sun rise 365 times, so we say there are 365 solar days. For sidereal days, that's 366 sidereal days.

The solar day is also called the earth day, the sidereal day is based on the star, and the solar day is based on the sun.

On a sidereal day, the Earth rotated 360 degrees in 23:56:4.

In one solar day, the Earth rotated 360 degrees and 56 minutes in 24 hours.

The difference between the two is that the Earth rotates around the Sun at the same time. If the Earth does not revolve, then it would be the same with the Sun or the stars as a reference point ...

But the earth rotates and rotates in the same direction, so when facing the sun twice at the same point, it is not only 360 degrees, but it should be 360 degrees and 56 minutes; If (assuming) the direction of revolution and the direction of rotation are opposite, then the same point is 359 degrees 04 minutes when facing the Sun twice;

If a distant star is used as a reference point, then the rotation of the earth can be ignored, and it can be approximated as the rotation in situ, so the time is shorter than the solar day.

So how do you calculate the time spent on the extra 56 points?

If it is known that one revolution of the earth is a day, then the average angular velocity of the earth per day is 360 degrees day=. This average velocity multiplied by the angle calculates the time.

Why is a solar day longer than a sidereal day? This is because sidereal days do not take into account the Earth's revolution and are the true cycle of the Earth's rotation. The solar day takes into account the Earth's revolution and is a cycle of alternating day and night.

The stars are very far away, so the Earth's orbital motion is negligible.