The Sun is a gigantic ball of gas and plasma that, with its brightness and mass , absolutely dominates the rest of the bodies in the Solar System . It accumulates approximately 99.8% of all mass and is therefore capable of dictating without question the orbits of the planets, asteroids and comets that orbit it . In addition, it keeps Mercury anchored with its gravity, it is responsible for the high temperature of the atmosphere of Venus and the presence of life on Earth, as well as the absence of an atmosphere around Mars. The solar wind reaches beyond the orbit of Pluto , creating auroras on any body with sufficient atmosphere and magnetic field.
And yet, when compared to other stars in the universe, the Sun is rather lackluster . Mediocre in the sense that there are millions of stars like him. Let’s see in this article 5 of the most extreme stars that we have discovered in our observation of the universe. Each one of them is different and each one of them special for a different reason. Of course, this list is not definitive and future research could reveal new stars that would make those mentioned here pale.
the longest star
The star HD 140283 , also sometimes called the Methuselah star, may be the oldest known star . Surprisingly despite this, it is only 200 light years distant from the Sun , in our own galaxy. This star, which would have formed in the first hundreds of millions of years of life in the Universe , would not have been one of the first to form, since its composition indicates that it was formed from the remains of other even earlier stars , which were not we have been able to observe.
The first stars must have formed from clouds containing almost exclusively hydrogen and helium , with minute traces of lithium. However, the star HD 140283 contains a small proportion of heavier elements, such as oxygen or iron , which could not be formed immediately after the Big Bang, but during the death of the first generation of stars.
The brightest star
The star RMC 136a1 is possibly the most luminous star known . It has an incredible mass of about 220 times the mass of the Sun and a luminosity 7 million times greater . It inhabits the center R136, the central region of the open star cluster NGC 2070, in the Tarantula Nebula in the Large Magellanic Cloud , the largest of our own galaxy’s satellite galaxies.
This star radiates as much energy in 4 seconds as the Sun radiates in a whole year . In fact, if we were to substitute Proxima Centauri, the closest star to the Sun, for RMC 136a1, the star would shine as bright as a full moon. Because it is so luminous and so massive (it is one of the most massive stars known) , its lifetime will be extremely short . It is currently just over a million years old and it is estimated that it should explode violently within a few million years.
the hottest star
The star WR 102 is located just over 9000 light-years away and is the star with the hottest known surface . In its photosphere , temperatures of about 210,000 ºC are reached , while the surface of the Sun is “only” 5,400 ºC. This is an incredibly compact star, packing more than 16 times the mass of the Sun into eight times less volume (its radius is half that of our star). WR 102 is at the end of its days. It has long since used up all of its hydrogen and it is believed that it may have used up all of its helium. This is why we believe it could explode as a supernova in less than 1,500 years , just the blink of an eye on astronomical scales.
the smallest star
This list doesn’t just have room for star monsters. SCR 1845−6357 is a binary system composed of one of the smallest known stars, with a mass of only 7% of the mass of the Sun (other known stars of similar sizes are TRAPPIST-1 with 9% of the mass of the Sun). Sol and Proxima Centauri with 12% the mass of the Sun) and a brown dwarf about 50 times the mass of Jupiter . The latter is part of a family of objects considered substellar, since it is considered that they do not have enough mass to sustain hydrogen fusion continuously, like a normal star, but they cannot be considered entirely as planets either.
The entire system is located just 12.6 light-years away , but despite being so close it was not discovered until 2004 due to its extremely low luminosity.
The star with the most exoplanets discovered
Kepler-90 is a star slightly larger than the Sun but half as old, located about 2,800 light-years away, and is the star with the largest number of confirmed exoplanets orbiting it. Other stars like Tau Ceti (which plays an important role in Andy Weir’s recent novel “Project Hail Mary”) could have up to 10 planets around them, although only 4 of these exoplanets have been confirmed .
The Kepler-90 planetary system, which has the same number of planets as our own , is also arranged in a similar way, with the small, rocky planets in the interior and the gas giants in the larger orbits. However, all of the Kepler-90 planets orbit closer to their star than Earth does to the Sun , except for the last, Jupiter-sized planet, which would orbit at about the same distance as our planet. In addition, the 6 rocky planets in the system are what we call super-Earths , all of them being larger than our world and some having a diameter almost 3 times larger.
REFERENCES:
Tang et al, 2021, Revised Best Estimates for the Age and Mass of the Methuselah Star HD 140283 using MESA and Interferometry and Implications for 1D Convection, Research Notes of the AAS, 5, 5, id.117, doi:10.3847/2515-5172/ac01ca
E.I. Doran et al, 2013, The VLT-FLAMES Tarantula Survey – XI. A census of the hot luminous stars and their feedback in 30 Doradus, Astronomy & Astrophysics, doi:10.1051/0004-6361/201321824
A.C. Andreas et al, 2019, The Galactic WC and WO stars: The impact of revised distances from Gaia DR2 and their role as massive black hole progenitors, Astronomy & Astrophysics, doi:10.1051/0004-6361/201833712
Kasper et al, 2007, The very nearby M/T dwarf binary SCR 1845-6357, Astronomy and Astrophysics, 471, 2, doi:10.1051/0004-6361:20077881
Cabrera et al, 2013, The Planetary System to KIC 11442793: A Compact Analogue to the Solar System, The Astrophysical Journal. 781 (1), doi:10.1088/0004-637X/781/1/18
