#AstroMiniBR: see direct images of exoplanets!

Every week, TecMundo this #AstroMiniBR Bring together five interesting and fun astronomical curiosities produced by Twitter profile contributors to spread the knowledge of this oldest science!

#1: How is it possible to see the stars during the day?

Yeah! It is possible to see the stars during the day. Attached to the Pico dos Dias Observatory’s 1.60m telescope, the telescope is used to confirm the accuracy of the telescope’s automatic aiming. This calibration can be done during the day with a bright star. #AstroMiniBR pic.twitter.com/d96opzQ4LW

— The Deep Sky Project (@CeuProfundo) 14 September 2022

When we think of watching the stars, our minds are immediately directed to the night sky.

Due to the intensity of sunlight during the day, the visibility of the stars is extremely poor during this period and is almost impossible to do with the naked eye, except for a few hours before sunset and in rare events such as solar eclipses.

Under normal conditions, for example, Sirius, the brightest star in the sky, would have to be 5 times brighter to be seen during the day. However, it is possible to see the stars during the day only with the help of instruments. Other individual, bright stars (besides the Sun, of course) can be seen during the day through a telescope or powerful binoculars. The trick is knowing exactly where to point them so that the star’s brightness—and more importantly, the lens’s ability to magnify and capture light—can outperform the glare of refracted sunlight.

Some telescopes now have automated systems and adaptive optics that make this task much easier. This is the state of the telescope in the above image at the Pico dos Dias Observatory in Minas Gerais.

#2: The sunspot cycle

?? Acne in the Sun every 11 years??

The Sun has larger activity cycles and sunspots appear at the zenith.

These dark regions are cooler than the rest of the surface, but have intense magnetic activity that leads to sudden eruptions.#AstroMiniBR pic.twitter.com/fqdExKiZln

— Ana Carolina Posses (@astroposses) September 9, 2022

The surface of the Sun is a very dense place. There are electrically charged gases there that create strong magnetic fields that circulate according to the motion of the plasma.

An interesting aspect of the Sun’s surface is sunspots: areas where the magnetic field is about 2,500 times stronger than Earth’s and much higher than anywhere else on the Sun. Due to the strong magnetic field, the magnetic pressure increases while the surrounding atmospheric pressure decreases. This lowers the temperature relative to the environment because the concentrated magnetic field blocks the flow of hot, new gas from inside the Sun to the surface.

Sunspots tend to form in pairs with magnetic fields pointing in opposite directions. They appear relatively dark because they have an average temperature of about 2000°C lower than the surrounding areas. In addition, these regions appear on average every 11 years and are roughly the size of Earth.

#3: Hertzprung-Russell diagram

A great way to describe stars by their brightness and temperature is to create a Hertzprung-Russel (HR) diagram.

here is the HR diagram of the ωCen cluster showing different types of stars inhabiting ?

{c} NASA, ESA, Anderson and van der Marel#AstroMiniBR pic.twitter.com/DkWpU0cZ3G

— yanna martins franco (@martins_yanna) 14 September 2022

In astronomy, the Hertzsprung-Russell diagram, also called an HR diagram, is a graphical representation of stars’ absolute magnitudes (inner luminosity) relative to their spectral types (temperature).

This theory, which is of great importance to theories of stellar evolution, developed from maps initiated in 1911 by Danish astronomer Ejnar Hertzsprung and independently by American astronomer Henry Norris Russell. In this diagram, the stars are arranged from bottom to top in decreasing order of magnitude and from right to left according to temperature increase.

The animation above shows the generation of an HR diagram for the star populations of the ?Cen cluster.

#4: Photographing craters on the Moon

Everyone traveling by plane took pictures from the window. And anyone who has traveled to the Moon! Here we see the Messier craters photographed by Apollo 11 astronauts in 1969. The elongated shape is due to the grazing angle of the bump that created them. #AstroMiniBR pic.twitter.com/G44FuLQEeW

— The Deep Sky Project (@CeuProfundo) September 9, 2022

Everyone loves to take photos while traveling. Can you imagine photos of people traveling to the moon?!

The above recording was made by NASA’s Apollo 11 crew, who first landed on the lunar surface in July 1969. It shows Messier craters, relatively young lunar landslide craters found in Mare Fecunditatis.

The craters called Messier (left) and Messier A are 15×8 and 16×11 km in size, respectively. Their elongated shape is explained by the extremely shallow angle trajectory followed by left-to-right impact. This shallow impact also resulted in two bright beams of material extending to the right across the surface, beyond the image.

#5: Record of extrasolar planets

Most of the images circulating in the outer planet media are the ideas of the artist.

However, we have direct images of some cases, such as the HR 8799 system (4 small boxes).

On the scale: 20 au = 20 times the distance between the Sun and the Earth.#AstroMiniBR pic.twitter.com/oHzR6oE3KU

— Ana Carolina Posses (@astroposses) 14 September 2022

The HR 8799 system is the first extrasolar planetary system to be seen directly in an astronomical image. HR 8799 is a young star (about 60 million years old) located 128 light-years from Earth in the constellation Pegasus.

Observations of this star by the Infrared Astronomical Satellite and the Infrared Space Observatory showed a dust disk exactly similar to the pattern expected for the final stages of planet formation. In 2008, an international team of astronomers released images of three planets orbiting HR 8799 taken with telescopes at the Keck and Gemini North observatories. A fourth planet was discovered in 2010.

Later astronomical observations showed that the planets did indeed move with the star and therefore could not be background objects. The masses of the planets range from 7 to 10 times that of Jupiter, and its orbit ranges from HR 8799 between 2.2 and 10.2 billion km (1.3 and 6.3 billion miles). These planets are gas giants with temperatures of about 600 to 800°C.