Author: Astronomy.WTF

The Constellation Cassiopeia

Cassiopeia, the queen of the northern night sky, is a prominent constellation that has captivated stargazers for centuries.

Named after the mythical queen from Greek mythology, Cassiopeia is easily recognizable for its distinctive “W” or “M” shape, depending on its position throughout the year.

Let’s embark on a celestial journey and unravel the wonders of this beautiful constellation and the stars that adorn it.

First, lets discover how the Constellation was born.

The Story of Cassiopeia Myth

The history of Cassiopeia mythological figure is directly linked to her constellation.

Cassiopeia, a proud queen, claimed her daughter Andromeda was more beautiful than the Nereids, angering Poseidon, the sea god.

Poseidon sought to punish her kingdom Ethiopia, either by flooding it or sending a sea monster.

To appease the sea gods, an oracle advised sacrificing Andromeda.

Andromeda was chained to a rock at the sea’s edge, awaiting the sea monster’s arrival.

However, Perseus arrived, slayed the monster, and married Andromeda.

Poseidon immortalized Cassiopeia in the heavens, binding her to a throne resembling a torture device.

Depictions of her vary, sometimes showing her holding a mirror or palm frond, symbolizing vanity.

Cassiopeia’s pride had grave consequences for her kingdom.

Through heroism and divine intervention, Andromeda was saved.

Cassiopeia’s celestial punishment serves as a reminder of the dangers of arrogance and vanity.

Thus, Constellation Cassiopeia was born!

How to Find the Stars of Cassiopeia Constellation

Cassiopeia is positioned in the northern celestial hemisphere, visible from latitudes between +90° and -20°. Its distinct “W” or “M” shape makes it easy to find.

Throughout the year, Cassiopeia seems to rotate around Polaris, the North Star, making it an excellent landmark for stargazers and navigator.

To locate the Cassiopeia constellation in the night sky, just follow this easy guide: 

1. Begin by finding the easily recognizable constellation of the Big Dipper, which is part of the larger Ursa Major constellation.
2. Locate the two stars at the end of the Big Dipper’s bowl
3. Draw an imaginary line from these stars, extending away from the bowl
4. You should be able to locate the Polaris Star
5. Continue along this line for roughly the same distance as the distance between the two stars, and you will reach Cassiopeia, with its distinctive “W” or “M” shape.

The shape varies on its orientation in the sky, which is effected by the seasonality of the sky.

It is visible in the northern hemisphere throughout the year and can be found high in the sky during autumn evenings.

The Stars of Cassiopeia Constellation

The Queen of the Sky is composed by five shining stars, α Alpha Cassiopeiae (Schedar), β Beta Cassiopeiae (Caph), γ Gamma Cassiopeiae (Cih), δ Delta Cassiopeiae (Ruchbah) and ε Epsilon Cassipeiae (Segin).

Together, they often are referred as Cassiopeia’s Chair or The Lady in her Chair.

“In charts of the constellations she is represented as a draped figure reclining in a chair and holding up both arms”, the following Pin describes this artistic representation.

Schedar, Alpha Cassiopeiae

Cassiopeia consists of five notable stars that contribute to its celestial beauty.

The brightest star in the constellation is Alpha Cassiopeiae, also known as Schedar, with a magnitude of 2.24 since it is a orange giant of the spectral type K0 IIIa.

With a luminosity over 1,000 times that of the Sun, Schedar stands out as a giant star, approximately 228 light-years away from Earth. Its surface temperature is around 4,500 Kelvin.

In the past, it was a common thought that Schedar had the same brightness as Caph, beta cassiopeiae.

This was related to the fact that they can appear brighter or fainter than the other, in different passbands: to the untrained eye, they could appear equally shiny.

Anyway, Schedar was confirmed to be marginally brighter by NASA’s WISE telescope.

Caph, Beta Cassiopeiae

Beta Cassiopeiae, also known as Caph, is another prominent star in the constellation.

It is a white giant star located around 54 light-years away from our planet.

Caph has a luminosity about 2,400 times greater than that of the Sun, making it a fascinating stellar object to observe.

Its surface temperature is estimated to be around 7,500 Kelvin.

Caph is almost 25 times less brighter than Schedar which has an energy output 676 times that of the Sun.

Comparing the distances, Schedar is about four times more distant than Caph, which shines 54.7 light-years away.

Cih, Gamma Cassiopeiae

Among the intriguing stars of Cassiopeia is Gamma Cassiopeiae, a peculiar variable star.

What makes unique Gamma Cassiopeiae, known as Cih (it has no traditional Arabic or Latin name), is its ability to undergo sudden and dramatic changes in brightness.

This phenomenon is caused by its rapid rotation, which causes the star to eject material into space, forming a surrounding disk.

Gamma Cassiopeiae is a massive blue-white subgiant star located approximately 550 light-years away from Earth.

Its surface temperature is estimated to be around 22,000 Kelvin.

However, the name Cih is derived from “Tsih”, the Asian star name which is meaning “Whip”; it is informally known also known as Navi.

Ruchbah, Delta Cassiopeiae

Delta Cassiopeiaen, or Ruchbah, is an eclipsing binary system with an apparent magnitude of 2.68, making it the fourth brightest star of the constellation.

It is distant 99.4 light-years and has a stellar classification of A5 IV which represents a subgiant white with a temperature of 7.980 K.

The star has already finished the hydrogen in its core so it evolved away from the main sequence;  it has 2.49 times the mass of the sun and 3.90 times its radius.

The star’s name “Ruchbah” comes from the Arabic rukbah, meaning “knee”; it refers to the star’s position in the constellation, marking the knee of the mythical Queen Cassiopeia.

Segin, Epsilon Cassiopeiae

Epsilon Cassiopeiae, commonly known as Segin, is a binary star system located approximately 440 light-years away.

The primary star is a blue-white giant, while its companion is a smaller star.

It is the fifth star in order of magnitude, which is 3.37, making it the faintest one.

Segin has the stellar classification B3 V, indicating that it is still melting hydrogen in its core.

Segin’s striking appearance and its position within the constellation add to the visual allure of Cassiopeia.

The primary star has a surface temperature of about 17,000 Kelvin.

Other Stars and Deep Objects in Cassiopeia

In addition to the notable stars, Cassiopeia is home to various deep-sky objects that fascinate astronomers, like the star cluster Messier 52, the bubble Nebula NGC 7635 and the ghost nebula IC 63.

Star Cluster Messier 52

The open star cluster Messier 52 is a stunning sight, composed of approximately 6,000 stars and located around 5,000 light-years away from Earth.

This cluster showcases a rich assortment of stars, with some appearing in striking colors, ranging from white and yellow to orange and red.

The cluster’s age is estimated to be around 35 million years, making it relatively young in astronomical terms.

Blubble Nebula NGC 7635

The famous Bubble Nebula (NGC 7635) can also be found within Cassiopeia, displaying a bubble-like structure created by the stellar wind from a massive, hot star located at its center.

The intense ultraviolet radiation emitted by this star interacts with the surrounding gas, creating the glowing shell of the nebula.

The Bubble Nebula provides astronomers with valuable insights into the processes of star formation and the interplay between massive stars and their interstellar environment.

Its distance from Earth is estimated to be around 7,100 light-years.

Ghost Nebula IC 63

Moreover, the eerie Ghost Nebula IC 63 adds an ethereal touch to the constellation with its wispy appearance.

This dim reflection nebula is illuminated by the nearby star Gamma Cassiopeiae, causing the surrounding dust and gas to scatter and reflect starlight.

The Ghost Nebula presents an intriguing subject for astrophotography enthusiasts due to its delicate features and faint glow.

It is located at a distance of approximately 550 light-years from Earth.

Supernova Cassiopeia A

One of the most well-known remnants of an exploded star, known as a supernova remnant, resides within Cassiopeia.

Cassiopeia A, or Cas A, is the remnant of a supernova explosion that occurred approximately 11,000 light-years away from Earth.

This celestial spectacle continues to be a subject of scientific study, offering valuable insights into the life cycle of stars.

Cas A provides astronomers with an opportunity to observe the aftermath of a supernova, enabling them to study the processes of nucleosynthesis and the dispersal of heavy elements into the surrounding interstellar medium.

Look at this overlay of several photographs that have taken the object at different wavelengths: gamma rays with their magenta, X-rays of blue and green colors, visible view of yellow, the infrared that is red and the radio, which is orange.

The Significance of Cassiopeia Constellation

Cassiopeia’s mythological roots and distinctive shape have made it a subject of fascination in various cultures throughout history.

In addition to Greek mythology, different civilizations have interpreted the constellation in their own ways.

For instance, in Chinese astronomy, Cassiopeia is known as the “Weaving Maid” and is associated with the tale of the Cowherd and the Weaver Girl, represented by the stars Vega and Altair, respectively.

Cassiopeia not only offers breathtaking sights and captivating stories but also serves as a valuable resource for scientific research.

The stars within the constellation provide crucial information about stellar evolution, from the birth of massive stars to their explosive deaths.

By studying these stars, astronomers gain insights into the processes that shape the cosmos and the elements that make up our universe.

From the mesmerizing glow of Alpha Cassiopeiae to the enigmatic variations of Gamma Cassiopeiae, each star within the constellation holds its own story and scientific significance.

Whether you gaze upon Cassiopeia to appreciate its stellar beauty, explore its deep-sky wonders, or immerse yourself in the stories woven through time, this enchanting queen of the night sky will continue to inspire and captivate stargazers for generations!

The night sky has always captivated human beings, inspiring awe and wonder.

Among the countless celestial treasures scattered across the firmament, the stars of Ursa Major holds a special place.

Also known as the Great Bear, Ursa Major is one of the most recognizable and prominent constellations in the northern hemisphere.

In the southern hemisphere, instead, it is only partially visible.

In this article, we will embark on a celestial journey through the stars of Ursa Major, deepening also the 7 Stars composing the Big Dipper.

We will unveil their magnificence and unravel their scientific significance.

The Constellation Ursa Major

Ursa Major is a prominent constellation that graces the northern sky.

It is often referred to as the “Big Dipper” due to its distinctive shape, which resembles a wagoon with tiller.

Comprising seven bright stars, Ursa Major forms part of the larger constellation Ursa Major Group.

The stars of Ursa Major have been observed and studied for centuries, offering valuable insights into stellar evolution and celestial navigation.

The 7 Stars of the Big Dipper

Alkaid (Eta Ursae Majoris)

Alkaid, also known as Eta Ursae Majoris, is the end star of the Big Dipper’s handle.

It is a blue-white main-sequence star located approximately 103.9 light-years away from Earth.

With a spectral classification of B3 V, Alkaid shines with an apparent magnitude of 1.86, making it one of the brightest stars in Ursa Major.

Its is also the 38th brightest star in the sky.

Remember that star’s magnitude is computed as the following.

Its high luminosity and intense radiation make Alkaid an intriguing subject for astronomers studying stellar atmospheres and spectroscopy.

Below, you can have a look at Alkaid compared to our Sun.

Dubhe (Alpha Ursae Majoris)

Dubhe, or Alpha Ursae Majoris, is the second-brightest star in Ursa Major and forms part of the Big Dipper’s bowl.

Classified as a K-type giant star, Dubhe exhibits a warm orange hue and is located approximately 124 light-years away.

With an apparent magnitude of 1.79, it is easily visible to the naked eye.

Dubhe is also an interesting binary star system, with a smaller companion that orbits the primary star.

This system provides valuable opportunities for studying stellar dynamics and interactions.

Merak (Beta Ursae Majoris)

Merak, or Beta Ursae Majoris, is the third-brightest star in Ursa Major and represents the tip of the Big Dipper’s bowl.

As a main-sequence star of spectral type A1,  Merak emits a white light and is located around 79 light-years away from our planet.

With an apparent magnitude of 2.37, it contributes to the constellation’s splendor.

Astronomers have studied Merak extensively to understand its composition, structure, and evolutionary stage, shedding light on the life cycles of stars.

Megrez (Delta Ursae Majoris)

Megrez, also known as Delta Ursae Majoris, is the faintest of the Big Dipper’s seven stars.

Despite its modest brightness of 3.32 , Megrez is an important marker in the constellation.

Classified as an A-type main-sequence star (A3), it lies approximately 81 light-years away from Earth.

Astronomers have utilized Megrez’s properties to refine the calibration of stellar evolutionary models, helping to unravel the mysteries of stellar birth and death.

Alioth (Epsilon Ursae Majoris)

Alioth, or Epsilon Ursae Majoris, is the brightest star in Ursa Major and resides at the end of the Big Dipper’s handle.

With a spectral classification of A1 IV, Alioth shines with a magnitude of 1.77.

It is located around 82.6 light-years away and exhibits a bluish-white glow.

Alioth is a fascinating target for astronomers studying stellar rotation and magnetic fields, providing crucial insights into stellar activity and dynamo mechanisms.

Mizar (Zeta Ursae Majoris) and Alcor (80 Ursae Majoris)

Mizar and Alcor form a double star system in Ursa Major, which has been known since ancient times.

Mizar is 82.9 light-years far while Alcor 81.7, meaning that these two stars of Ursa Major, should be far about 1.2 light-years.

Alcor has an apparent magnitude of 3.99 while Mizar one of 2.04.

Mizar, also known as Zeta Ursae Majoris, is the middle star of the Big Dipper’s handle, while Alcor, or 80 Ursae Majoris, is a fainter star nearby.

Mizar itself is a well-known multiple star system, composed of at least four stars.

This makes it an intriguing target for astronomers studying stellar dynamics and stellar evolution.

Mizar and Alcor also serve as a popular visual test for eyesight and have been used by navigators as a gauge of visual acuity.

Phecda(Gamma Ursae Majoris)

Phecda or Gamma Ursae Majoris, is the second star from the end of the Big Dipper’s bowl.

As a K-type giant star, Phecda has a distinct orange-red hue and is located approximately 83 light-years away.

It shines with an apparent magnitude of 2.44, class A0Ve, adding to the constellation’s beauty.

Astronomers have studied Phecda to gain insights into stellar evolution and understand the processes occurring in the outer layers of giant stars.

Tania Australis (Mu Ursae Majoris)

Outside the Big Dipper, Tania Australis, also known as Mu (μ) Ursae Majoris, is a binary star system located in the southern part of Ursa Major.

It consists of two stars in orbit around a common center of mass.

Tania Australis is composed of a red giant main-sequence star of 3.06 magnitude and far about 249 light-years, and a smaller companion star.

It is an advanced star in its evolution, it has finished hydrogen in its core, and now it is contracting and then starting to melt helium into heavier elements.

This process is similar to others red giant stars.

This system provides astronomers with an opportunity to study stellar binaries and explore the dynamics of multiple star systems.

The Significance of Ursa Major Stars

The stars of Ursa Major not only offer captivating sights but also provide valuable scientific data.

Astronomers study these stars to gain insights into stellar formation, evolution, and dynamics.

By observing their spectra, astronomers can determine their compositions, temperatures and luminosities.

Additionally, binary star systems in Ursa Major provide a unique laboratory to study gravitational interactions and stellar evolution.

The knowledge gained from studying the stars of Ursa Major contributes to our broader understanding of the cosmos and helps refine theories of stellar physics.

From the brilliant blue-white Alkaid to the warm orange Dubhe, each star in this constellation offers a unique glimpse into the vast cosmos.

So, the next time you gaze up at the night sky and spot the Great Bear, remember that the stars of Ursa Major are not just captivating sights but also windows into the wonders of the universe.

Belt Stars Orion, Exploring the Magnificent

The constellation of Orion, with its striking belt arrangement of stars, has captivated stargazers for centuries: among its prominent features are the three aligned bright stars that form the iconic “belt” of Orion.

These celestial gems, known as Alnitak, Alnilam, and Mintaka, hold both scientific and cultural significance.

Before beginning our celestial journey, have a look at this astonishing amateur picture of Orion constellation.

Did you know that astronomical pictures require much exposure time and hardwork?

For this one, it has been required 90 minutes, that is to say 30 seconds each photo for about 180 pictures in total (800 ISO).

That time just to take one picture!

In this article, we delve into the fascinating characteristics of the Belt Stars of Orion, unveiling their astronomical wonders and shedding light on their role in our understanding of the cosmos.

However, Orion constellation is made of eight stars, whose characteristics are described below.

Alnilam is the brightest star of the belt while Rigel is the shiniest element of the constellation.

Name	Bayer designation	Light years	Apparent magnitude
Betelgeuse	α Orionis	548	0.50
Rigel	β Orionis	863	0.13
Bellatrix	γ Orionis	250	1.64
Mintaka	δ Orionis	1,200	2.23
Alnilam	ε Orionis	1,344	1.69
Alnitak	ζ Orionis	1,260	1.77
Saiph	κ Orionis	650	2.09
Meissa	λ Orionis	1,320	3.33

Remind that in Astronomy, the Apparent Magnitude of a star is computed as:

In other words, the brightness of a star is expressed through a comparison to a reference value (m_ref) and since it is using negative logarithmic 10 base scale, the lowest the value, the brightest the star.

Alnitak, the Dynamic Stars Belt Trio

Alnitak, the easternmost star in Orion’s belt, is a multiple star system located approximately 1,280 light-years away from Earth.

According to Star-facts.com, it has an apparent magnitude of 1.77 which makes it the 5th brightest star in Orion and the 31st brightest star in the sky, sharing the 31sh place with Alioth, the brightest star in Ursa Major.

It consists of three stars: Alnitak A, Alnitak B, and Alnitak C.

Alnitak A, the primary component, is a massive blue supergiant: with a luminosity over 100,000 times that of our Sun, it ranks as one of the most luminous stars in the Milky Way.

Alnitak B is a hot, blue-white star, while Alnitak C is a dimmer, fainter companion.

This trio of stars forms a breathtaking sight when observed through a telescope, revealing the intricacies of stellar dynamics.

Alnitak A, with its immense size and energy output, plays a crucial role in shaping the surrounding interstellar environment.

Its powerful stellar winds and intense ultraviolet radiation sculpt nearby clouds of gas and dust, triggering the formation of new stars.

These stellar nurseries give birth to clusters of young, hot stars, enriching the Orion constellation with stellar diversity.

Alnilam, the Brightest Belt Stars

At the center of Orion’s belt lies Alnilam, a luminous blue supergiant situated approximately 1,344 light-years from Earth.

Alnilam shines with a brilliance exceeding 375,000 times that of our Sun.

Its immense size and energy output classify it as one of the most massive and intrinsically luminous stars known to humanity.

Alnilam’s radiance illuminates the surrounding interstellar dust, giving rise to the famous “Horsehead Nebula” and contributing to the complex interplay of light and matter in the Orion constellation.

Alnilam’s colossal mass, estimated to be over 30 times that of the Sun, makes it a prime candidate for eventual supernova explosion.

Such cataclysmic events mark the end of massive stars’ lives and unleash tremendous amounts of energy and heavy elements into space.

The remnants of these explosions, known as supernova remnants, continue to influence the interstellar medium, fostering the formation of new generations of stars and enriching galaxies with vital building blocks for planetary systems.

Mintaka, the 4 Stars Multiple System

Mintaka, the westernmost star in Orion’s belt, is a multiple star system located roughly 1,200 light-years away.

It consists of four main components: Mintaka A, Mintaka B, Mintaka C and Mintaka D.

Mintaka A is a massive blue giant, while Mintaka B is a companion star with a slightly smaller mass.

Mintaka C and Mintaka D are two dimmer stars that complete the stellar quartet.

Mintaka has been studied extensively due to its peculiarities, including its variable brightness caused by interactions within the system.

Such investigations deepen our understanding of stellar evolution and binary star systems.

Mintaka’s variable nature provides astronomers with valuable insights into the complex dynamics of binary star systems.

These systems, composed of two or more stars orbiting around a common center of mass, are common in the universe.

Through detailed observations and analysis of Mintaka, scientists gain a deeper understanding of stellar interactions, mass transfer, and the ultimate fate of such systems.

Furthermore, Mintaka’s variable brightness contributes to the wealth of data used to refine and calibrate astronomical models and techniques.

Astronomical Significance, Stars Evolution and Telescopes Calibration

The Belt Stars of Orion hold immense astronomical significance beyond their visual allure.

Their massive and energetic natures provide valuable insights into stellar formation, evolution, and death.

The study of these stars enables scientists to probe the processes governing the birth and dynamics of massive stars, as well as the subsequent dispersal of heavy elements into space through supernova explosions.

Additionally, the Belt Stars serve as crucial calibration points in stellar classification, aiding astronomers in determining the properties of distant stars through comparative analysis.

The lifecycle of massive stars, from their formation in stellar nurseries to their explosive demise as supernovae, plays a fundamental role in shaping the cosmos.

Through the observations of the Belt Stars of Orion and similar massive stars, astronomers gain insights into the mechanisms that govern the evolution and fate of these luminous giants.

The knowledge derived from studying these stars helps refine our understanding of stellar populations, galaxy evolution, and the synthesis of elements necessary for the emergence of life.

Cultural Connections, the Role of Egypt and Greece

The Belt Stars of Orion carry cultural significance across various civilizations.

From ancient Egypt to indigenous cultures in North America, Orion has been a focal point of mythologies and celestial navigation.

However, the constellation name is referred to the Greek Giant Orion, a giant huntsman whom Zeus (or perhaps Artemis) placed among the stars.

In Greek literature, he appears for the first time as a great hunter in the epopee of Homer the Odyssey, where Ulysses sees his shadow in the underworld.

The alignment of the Belt Stars with other prominent celestial objects has guided human exploration and facilitated the mapping of the night sky.

Even today, the Belt Stars of Orion continue to inspire astronomers and sky watchers alike, reminding us of our timeless fascination with the cosmos.

In ancient Egypt, the Belt Stars of Orion were associated with Osiris, the god of the afterlife.

The annual rising of Orion coincided with the flooding of the Nile, symbolizing rebirth and renewal.

In other cultures, such as the indigenous tribes of North America, the Belt Stars served as important markers for seasonal activities, celestial calendars, and navigation across vast landscapes.

The Magnificent of Belt Stars Orion

The Belt Stars of Orion, Alnitak, Alnilam, and Mintaka, embody the grandeur of the cosmos.

Situated within the iconic constellation, these stars dazzle us with their brilliance and beckon us to unravel the mysteries of the universe.

Through scientific inquiry and cultural appreciation, we continue to explore and celebrate these celestial marvels, expanding our knowledge of the cosmos and deepening our connection to the vastness of space.

If you have reached the end of this article, you can collect our image-prize: admire the Orion Nebula!