Stellar Notes

[Terpsícore Deckelman]

Whateveryour academic preparation for college or your level of confidence about succeeding in your courses this semester, you can improve your learning experience, the quality of your work, your ability to remember, and your grades by taking better notes.

Print the template on regular computer paper. You might have to play around with the settings before you start mass producing your sticky notes. You want to make sure that when you print the template you have a 3in x 3in square that will perfectly fit your sticky note.

With this freebie, you'll get everything you need to get started with word of the day in your classroom. You'll get all the student and teacher materials for five days. Word of the day will help your students become experts at using context clues.

The Stellar Blade Summer Update is here! Enjoy a limited-time summer vacation area at the Great Desert Oasis, complete with special summer-themed music. Also, check out new outfits and accessories available at Clyde's shop. Read the full patch notes below.

Note: the first part of the call was lost. The video posted above captures the second half of the call where various ecosystem developers shared their use cases and needs for a smart wallet on Stellar.

Piyal from Freighter discussed the proposal to standardize the wallet interface. Key points from the discussion are captured below. For full notes, please view the recording; and also refer to the proposal and the post on github discussions.

Today's recording has two parts. The first 12 minutes are audio-only. The next 45 minutes have video as well.Please note the slides were shared in discord chat over screensharing, due to technical difficulties.

The solar system is comprised of the Sun, eight planets, several dwarf planets, numerous moons, and hundreds of thousands of other material left over from the construction of the solar system such as asteroids and comets.

Cepheid variable: A star with a period of varying luminosity. The luminosity can be determined from the period and along with the apparent brightness can be used to determine the distance of the star from Earth.

Example: The distance to the nearest star other than the Sun (Proxima Centauri) from the Earth is 4.31 light years, which is equivalent to 1.3pc. This means that it would take 4.31 years to send or receive a message to/from Proxima Centauri by electromagnetic wave transmission.

The average distance between stars in a galaxy is approximately 1 pc, which is equivalent to 3.26 light years. The average distance between galaxies within the same cluster ranges from 100 kpc (kiloparsecs) to several hundred kpc. Galaxies in different clusters can be up to a few mpc (megaparsecs) apart. 1 mpc is equivalent to 1000 kpc.

Stellar parallax is a term used to describe the distance between two objects in space. When an observer on Earth photographs a relatively nearby star against a background of distant stars on two different occasions six months apart, the target star image will appear to have shifted against the more distant stellar background.

If two stars were at the same distance from Earth, the one that had the greatest luminosity would also have the greatest brightness. However, because stars are at different distances from the Earth, their brightness will depend on the luminosity as well as the distance from Earth. The luminosity of a star will decrease with distance according to the inverse square law.

As temperature increases, electrons are kicked up to higher levels by collisions with other atoms. Large atoms have more kinetic energy, and their electrons are excited first, followed by lower mass atoms.

If the collision is strong enough (high temperatures) then the electron is knocked off the atom and we say that the atom is ionized. So as we go from low temperatures in stars (a few thousand Kelvins), we see heavy atoms, like calcium and magnesium, in the stellar spectra. For stars with higher temperatures, we see lines from lighter atoms, such as hydrogen. The heavier atoms are all ionized by this point and have no electrons to produce absorption lines.

The H-R diagram is also used by scientists to help the figure out roughly how far away the stars are from Earth. This can be done because if we know the apparent magnitude, we can plot the star onto the graph using its spectral class and the type of star it is. We can then use the graph to deduce the absolute magnitude of the star.

Cepheid variables are stars in which its luminosity increases sharply and falls gently in a period of time. Thus, the period is correlated to the luminosity of the star and the Cepheid variable can be used to estimate the distance of the star.

Cepheid variables on a luminosity-period graph, due to their brightness increase and gradual fade offs, curves on the graph, giving a sine graph picture. The outer layers of the star go through contractions and expansions periodically. When it expands outward, the star becomes brighter because of high velocity, and when it contracts, the star becomes dimmer as the surface it moves inward.

The nebulae in space from which stars are created are actually the remains of a previous star that has reached the end of its lifecycle and died. Generally speaking, they consist of hydrogen and helium and small amount of the other heavier elements. The nebula, under the influence of gravity, begins to condense, and eventually, a protostar is formed. Such protostars can be observed in nebulas such as the horsehead nebula and the crab nebula. It is in this stage that the process of nucleosynthesis begins. Nucleosynthesis, in contrast to the nuclear processes that we are used to on Earth, is fusion, not fission. That is, instead of splitting a heavy nucleus, light nuclei are smashed together and fuse to produce a heavier nucleus, and gamma rays. It is called the proton-proton cycle. The star will continue to react its core of hydrogen into helium for all of its main-sequence lifetime (see previous section: the nature of stars).

Once the star runs out of hydrogen, the core collapses, and, under the additional gravitational pressure, the hydrogen in the core will start to undergo fusion. This causes the outer layers of the star to expand, however, the outer layers also cool, and the star becomes a red giant. The core continues to react and elements such as carbon, neon, oxygen, silicon and iron are produced. It is here that the elements that compose our world are created. Without the stars then universe would be composed of hydrogen and little else.

When the star finally runs out of fuel completely; usually when the core becomes iron, the red giant star collapses. The next stage of the star is determined by the mass of that star and the Chandrasekhar limit.

If a star is below 1.4 solar masses (Type G), it is less that the Chandrasekhar limit and when it collapses, its forms a white dwarf of 1.4 solar masses or less, along with a planetary nebula. The white dwarf star continues to cool and eventually becomes invisible.

If a star is above 1.4 solar masses (Type A, B, O), it is above the Chandrasekhar limit and instead of becoming a regular red giant, it becomes a super red giant. In this case, when the star dies, it takes a rather more spectacular path than the star below the Chandrasekhar limit, becoming a supernova. Depending on the mass of the star, it will either go on to become a black hole or a neutron star.

For stellar masses less than about 1.4 solar masses, the energy from the gravitational collapse is not sufficient to produce the neutrons of a neutron star so the collapse is halted by electron degeneracy to form white dwarfs. Electron degeneracy is a stellar application of the Pauli Exclusion Principle, as is neutron degeneracy. No two electrons can occupy identical states, even under the pressure of a collapsing star of several solar masses.

Oppenheimer-Volkoff limits the largest mass a neutron star can have to approximately 2-3 solar masses. The uncertainty in this limit comes from the fact that the equation of state of the matter inside a neutron star is not precisely known.

Although that observation would seem to indicate that we, or rather, the Earth, are at the centre of the universe, this is not the case. It only appears to be this way as we are observing from the Earth. If we were on a different galaxy, we would see our own galaxy moving away in the same manner as we are observing that galaxy moving away. This can be related to the idea of painted dots on the surface of a balloon; as the balloon is inflated, all of the dots move away from each other equally.

The evidence for an accelerating expansion comes from observations of the brightness of distant supernovae. We observe the redshift of a supernova which tells us by what the factor the Universe has expanded since the supernova exploded. This factor is (1+z), where z is the redshift. However, in order to determine the expected brightness of the supernova, we need to know its distance now. If the expansion of the Universe is accelerating due to a cosmological constant, then the expansion was slower in the past, and thus the time required to expand by a given factor is longer, and the distance now is larger. But if the expansion is decelerating, it was faster in the past and the distance now is smaller. Thus for an accelerating expansion, the supernovae at high redshifts will appear to be fainter than they would for a decelerating expansion because their current distances are larger.

We used GitHub links for Confluence by Move Work Forward to integrate GitHub and Confluence to embed into Confluence GitHub issues, pull requests, milestones, releases, files and many more things to make your release notes better.

The dance of light and matter in stars, though distant, becomes intimate through the tools and concepts unfolded in this segment. Every measurement, conversion, and spectral interpretation is a step towards a more profound celestial communion, where the stars, in their silent eloquence, unveil the cosmos's grandeur and intricacies to the attentive observer. Each concept, from the subtle shift of stellar parallax to the eloquent narratives inscribed in spectral lines, invites students into a universe rich in phenomena that echo the cosmic symphony of light, matter, and energy.

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