Formation of low mass protostars and their circumstellar disksSérgio Sacani
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3. There are an estimated one hundred
billion stars in the Milky Way Galaxy.
About 3,000 stars are visible to the
unaided eye
About 100,000 stars can be seen
using a small telescope.
4. Constellation
• a collection or group of stars
• imaginatively linked together
that form patterns like a person,
animal, or object in the night
sky.
5. Many constellations have names
that can be traced back early
Babylonians and Greek
civilizations, but nearly all
cultures have different names for
the constellations.
How the constellations got their names?
6. ■ Greeks called the large
constellation Orion, which means
hunter and is prominent in the
night sky all over the world during
winter.
■ Early Filipinos visualized the same
group of stars as Balik, a trap used
in hunting wild pigs. Christian
How the constellations got their names?
7. - International Astronomical Union
(IAU)
-recognized 88 modern
constellations,
-48 are based upon those recorded
by the Greek astronomer Ptolemy
around 150 AD in his treatise
called ‘Almagest’.
42 depict animals
29 relate to objects
17 portray humans or mythological
1922
9. Apparent Motion of Stars
- constellations appear to move across
the night sky due to the Earth’s rotation.
- This motion is responsible for the
changing positions of constellations
throughout the night and across
seasons
10. Star Clusters
- groups of stars that are physically close to e
other.
- example: Pleiades in Taurus (more than 1000
stars)
- Beehive cluster in Cancer
11. Galactic Perspective
- constellations give us a perspective on
our position within the Milky Way Galaxy.
- We see stars within our galaxy as part
of these patterns, but there are billions
of other galaxies beyond our own
12. Distance and Brightness
- stars within constellations can vary
greatly in distance from Earth and
consequently, in their apparent
brightness.
- this helps demonstrate the vastness of
the universe
13. Astronomical Coordinates
- constellations are used in celestial
coordinate systems like right ascension
and declination, which are essential for
locating objects in the night sky
precisely.
14. Constellation Nomenclature
- International Astronomical Union
(IAU) standardizes the names and
boundaries of constellations to
ensure consistency in astronomical
observations and studies
15. Astronomical Observations
- use constellations as reference
points to locate and study
celestial objects such as stars,
planets, galaxies, and nebulae
16. The constellations that are
known today cover the celestial
sphere.
• The celestial sphere is an
imaginary sphere surrounding
Earth.
• Ecliptic is the apparent path of
objects in the sky. The ecliptic is a
line where the plane described by
the Earth's orbit around the Sun
17. Within constellations, there are
smaller groups of stars.
• Asterisms are
smaller patterns of
stars within a
constellation.
• Asterisms are not
18. • Stars in constellations and
asterisms are at different distances
from Earth.
• They only appear as groups because
of their directions.
The grouping of stars into
constellations are not physical
groupings
19. Star patterns are grouped into
constellation families based on two
factors:
• They depict figures from a certain
ancient myth.
• Their distances are close to one
another when viewed from Earth.
20. Constellation families
• are groups of constellations that are either
located in the same area of the sky as
defined by Donald H. Menzel
Constellation families are:
• Ursa Major Family, Zodiac Family, Perseus
Family, Hercules Family, Orion Family,
Heavenly Waters Family, Bayer Family and
21. • URSA MAJOR FAMILY
• a group of 10 constellations
composed of Ursa Major, Ursa
Minor, Draco, Canes Venatici,
Boötes, Coma Berenices,
Corona Borealis,
Camelopardalis, Lynx, and Leo
Minor.
• This family can be found
around the north celestial
pole.
22. How many zodiac
constellations are there?
Zodiac Family
• 12 constellations in the zodiac family and
can all be seen along the ecliptic.
• They are: Aries, Taurus, Gemini, Cancer, Leo,
Virgo, Libra, Scorpius, Sagittarius,
Capricornus, Aquarius and Pisces.
• The Sun also passes through Ophiuchus, a
constellation that has traditionally not been
part of the zodiac family. It belongs to the
Hercules family.
Illustration of the “zodiac band” with a few of
the constellations depicting the objects they
represent.
23. The Perseus Family or Perseus
Group
■ is a group of 9 constellations
composed of Cassiopeia, Cepheus,
Andromeda, Perseus, Pegasus, Cetus,
Auriga, Lacerta, and Triangulum.
■ It spans from near the north celestial
pole down to –30° and the spring
meridian crosses this family.
■ Six of the constellations are named for
figures in the Perseus myth - Perseus,
his winged horse Pegasus, Andromeda,
her parents Cepheus and Cassiopeia,
and the sea monster Cetus.
24. The Hercules Family
■ is a group of 19 constellations com
posed of Hercules, Sagitta, Aq
uila, Lyra, Cygnus, Vulpecula, Hydra,
Sextans, Crater, Corvus, Ophiuchu
s, Serpens, Scutum, Centauru
s, Lupus, Corona Australis, Ara,
Triangulum Australe, and Crux.
■ Several of the constellations, inclu
ding Hercules and Centaurus, are
named for figures in the Heracles m
y, while Lyra is the lyre of Orpheus.
25. The Orion Family
■ is a group of 5 constellations
composed of Orion, Canis Major,
Canis Minor,
Monoceros, and Lepus.
■ This group of constellations re
presents the hunter (Orion) an
d his two dogs (Canis Major an
d Canis Minor) chasing the har
e (Lepus).
26. Heavenly Waters
also known as the Cosmic Waters, is a group of 9 constellations composed of
of Delphinus, Equuleus, Eridanus, Piscis Austrinus, Carina, Puppis, Vela, Py
xis, and Columba.
These constellations are associated with lake, river, sea creatures, and ship, in re
p, in reference to
the former constellation Argo Navis, which included what is now Carina, Puppi
pis, and Vela.
27. Bayer Family
is a group of 11 constellations composed of Hydrus, Dorado, V
olans, Apus, Pavo, Grus, Phoenix, Tucana, Indus, Chamaeleon
and Musca.
These constellations were introduced to the public by Johann
n Bayer (hence the name) in 1603.
All are named after animals, mostly water animals like the water
ter snake (Hydrus) and the goldfish (Dorado).
located in the far southern sky, they were not visible for the anc
ncient Greeks and Romans.
Bayer acquired them from Petrus Plancius who had directed oth
28.
29. La Caille Family
is a group of 13 constellations composed of Norma, Circinus, T
Telescopium, Microscopium, Sculptor, Fornax, Caelum, Horolo
ogium, Octans, Mensa, Reticulum, Pictor, and Antlia.
These constellations were introduced by Nicolas Louis de Lacail
caille (hence the name) in 1756.
Mensa (the table; originally "Mons Mensa" for table mountain) wa
32. Orion, the Hunter
■ It represents the mythical
hunter Orion.
■ Its brightest stars are
Betelgeuse and Rigel.
■ It contains an asterism of
three stars (Alnilam,
Mintaka and Alnitak) in a
straight line known as
33. Draco is one of the largest
constellations in the sky.
Located in the northern
celestial hemisphere, the
constellation represents
Ladon, the dragon that
guarded the gardens of the
Hesperides in Greek
mythology. The name
34. Ursa Major
• also known as the
Great Bear, is the
third-largest
constellation in the
sky and the largest
constellation in the
Northern
Hemisphere.
• It includes the Big
35. Ursa Minor
• lies in the northern sky. The
constellation’s name means
“the smaller bear,” or “the
lesser bear,” in Latin.
• The Great Bear constellation
is represented by its larger
neighbor Ursa Major.
• It is easy to recognize
because it contains the
famous Little
36. Cassiopeia
• is a large constellation
located in the northern
sky.
• It was named after
Cassiopeia, the vain and
boastful queen in Greek.
• Cassiopeia is easily
recognizable for the
prominent “W” asterism
formed by its five
40. Ans.
Not necessarily. Each constellation is a collection of
stars that are distributed in space in three
dimensions – the stars are all different distances
from Earth. The stars in a constellation appear to be
in the same plane because we are viewing them from
very, very, far away. Stars vary greatly in size,
distance from Earth, and temperature. Dimmer stars
may be smaller, farther away, or cooler than
brightber stars. By the same token, the brightest
stars are not necessarily the closest. Of the stars in
Cygnus, the swan, the faintest star is the closest and
41. 2. Are the stars in a constellation
near each other??
42. Ans.
No, there are billions of stars, and
only a fraction of them make up the
shapes of our constellations —
these are the stars that are easily
seen with the unaided eye. Ancient
observers connected these stars
into the star pictures.
43. WHAT ARE CONSTELLATIONS
USED FOR?
Constellations have served many different purposes throughout
the years. Because they appear in the sky at specific locations
during different times of the year, constellations have been
used to:
• Remind farmers to plant and harvest crops.
• Help travelers navigate through deserts and across oceans.
• Used to represent heroes and mythical creatures that have
been the subjects of folk tales down through the generations.