Reach for the Stars

Reach for the Stars is a Division B event. This event rotates every two years with Solar System. It was previously an event during the 2011-2012 season, 2012-2013 season, 2015-2016 season, and 2016-2017 season.

For information pertaining to the 2011-2012 rules, see Reach for the Stars 2011-2012.

2016-2017 Rules
Each team is allowed to bring 2 double-sided 8.5" x 11" sheets of notes, and may be asked to bring a clipboard and red filtered flashlight. You are allowed to put anything on this paper, such as text, illustrations, tables, and pictures. Calculators are also allowed unless told otherwise by event supervisors.

Part I
In Part I, students are asked to identify a specified list of stars, constellations, and deep sky objects (DSOs), which may appear on star charts, HR diagrams, planetariums, or other forms of display. Teams must also be knowledgeable about the evolutionary stages of the stars and deep space objects on the list.

Star Charts
During competitions, the star charts given can be from any location on Earth, in any season and at any time of the night. Therefore, it is crucial to be able to recognize stars and constellations in any orientation.

Below are three star charts that together cover all Stars and Deep Sky Objects from the 2017 Reach for the Stars list. Mizar and Alcor are binary systems, while 30 Doradus is in the Large Magellanic Cloud. NYC, Summer Solstice



NYC, Winter Solstice



Sydney, Summer Solstice



Stars
These are the stars from the 2016-2017 list (not in alphabetical order). With multiple-star systems, the Apparent/Absolute Magnitude is the combined Apparent/Absolute Magnitude of the stars: 2016-2017 List

Deep Sky Objects
These are the DSOs (Deep Sky Objects) from the 2016-2016 list (not in alphabetical order):


 * NGC 7293 (Helix Nebula):
 * NGC 3603:
 * NGC 3372:
 * Cassiopeia A:
 * Tycho's SNR:
 * Cygnus X-1: Cygnus X-1 is a source of x-rays in the constellation Cygnus. It is the first widely accepted black hole to be an x-ray source such as itself. It was discovered in 1964 and is located about 6,070 light years from the sun. Cygnus X-1 is a member of a high-mass X-ray binary system. It is about 5 million years old and rotates once every 5.6 days.
 * 30 Doradus: Located in the constellation of Dorado, 30 Doradus is an H II region also known as the Tarantula Nebula. It is found in the Large Magellanic Cloud (LMC) and has a magnitude of 8.
 * LMC:
 * Geminga:
 * NGC 602:
 * M57 (Ring Nebula):
 * Kepler's SNR:
 * M42 (Orion Nebula):
 * Sagittarius A*:
 * M17:
 * M8:
 * M16 (Eagle Nebula):
 * M1 (Crab Nebula):
 * T Tauri:
 * SMC:

Identification Tips

 * Go outside and look at the night sky. This is a great way to learn the constellations. Look up into the sky and use a star chart to find constellations and stars. Doing this even a few times a month really pays off.
 * Flash cards with the constellation/star/DSO on the front and its name on the back can really help. Make different flash cards with different information on the front page, such as constellation shape, location on a star chart, or pictures.
 * Another tip is to use Quizlet, which is great for studying constellations, stars, and DSO's, and may show images that could be seen on a test.
 * When working with star charts or looking at the night sky, many have found it very helpful to relate easy-to-find constellations such as Orion or Ursa Major (Big Dipper) to the constellations around them. This guides you to the constellation via others, rather than having to rely only on the shape. It may be helpful to include a section on the reference sheet about finding constellation you have trouble with on a sky chart. Common "pathways" include:
 * Using the handle of the Big Dipper asterism to find Bootes and Arcturus, and Virgo and Spica, and using the cup to find Ursa Minor and Polaris.
 * Using Orion to find Taurus, then Auriga, and then Gemini, Perseus, and Andromeda. Cassiopeia is also good for finding Perseus and Andromeda.
 * Looking for the Winter Triangle (Betelgeuse, Sirius, Procyon) and Summer Triangle (Vega, Altair, Deneb) to find those stars and constellations.
 * Using the Zodiac constellations, which are close to each other around the Ecliptic. This helps with Leo, Virgo, Scorpius, Sagittarius, and Ophiuchus (along with Serpens) especially, but also Gemini and Taurus.
 * Sometimes, the test will use a StarLab or planetarium for the identification portion. Put some time in to familiarize yourself with how the skies look on it. This will help reduce confusion on the identifications and reduce the amount of time spent on those questions.
 * There is always a chance that a bad star map may be used, so make sure to get accustomed to using less-than-clear maps and images.
 * In general, the brightest star (lowest apparent magnitude) in a constellation is denoted Alpha, and second brightest Beta, and so on. After the Greek alphabet has been used up, numbers are used - 1 is dimmer than Omega but brighter than 2. However, there are exceptions: Betelgeuse (Alpha Orionis) usually appears dimmer than Rigel (Beta Orionis), and Castor (Alpha Geminorum) appears to be dimmer than Pollux (Beta Geminorum).
 * While identification is not the only part of this event, it is a good way to begin preparing. For the rest of the event, see Part II. A good resource is Astronomy Today.

Part II
In Part II, students are asked to complete tasks relating to a set of particular topics. Teams must know about the general characteristics of stars, galaxies, star clusters, etc, and be able to figure out a star's spectral class, surface temperature, and evolutionary stage (i.e. giant, supergiant, main sequence, white dwarf) by reading an H-R diagram.

Teams are often asked to use information which includes the following:


 * Hertzsprung-Russell diagrams
 * Spectra
 * Light curves
 * Kepler's laws
 * Radiation laws (Wien's and Stefan-Boltzmann)
 * Period-luminosity relationship
 * Stellar magnitudes and classification
 * Parallax
 * Redshift/blueshift
 * Slides (PowerPoint)
 * Photographs
 * Star charts and animations

Stellar Evolution
''This section is intended to give a brief overview of Stellar Evolution. A more detailed discussion of stellar evolution may be found on the Astronomy/Stellar Evolution page, and other associated pages.''

Pictures
Know these pictures, credited from Harvard's Chandrasekhar X-Ray Observatory and Hubble Space Telescope. Teams are frequently tasked with putting pictures like these in order based on the stellar life cycle.

Cas A (Cassiopeia A) - supernova remnant (infrared, optical, radio, and X-ray images)



M1 (Crab Nebula) - Nebula (infrared, optical, radio, and X-ray images)

Crab Pulsar - fastest pulsar known (30 pulses per second)

Orion Trapezium Cluster - 4 hot young stars in an open cluster in the Orion Nebula

M57 (Ring Nebula) - Planetary Nebula (optical, infrared)



Harvard Spectral Classification
There are 7 spectral Classes (O,B,A,F,G,K,M). This order is based on decreasing surface temperature. A Class stars have the strongest Hydrogen lines, while M-Class stars have the weakest hydrogen lines. Each class is then subdivided into 10 subdivisions (0-9).

The following is a table with properties of each of the spectral classes.

The following is the class of each of the stars on the list:

Class O- None on the list

Class B- Rigel, Spica, Regulus, and Algol

Class A- Vega, Sirius A, Deneb, Altair, and Castor

Class F- Procyon, and Polaris

Class G- The Sun, and Capella

Class K- Arcturus, Aldebaran, and Pollux,

Class M- Betelgeuse, Wolf 359, and Antares

There are also S, N, and Y for brown dwarfs, which are generally not considered stars.

Yerkes Spectral Classification
The Yerkes Spectral Classification is based on luminosity and temperature. It is also known as luminosity classes. There are seven main luminosity classes:

Type Ia- Bright Supergiants

Type Ib- Normal Supergiants

Type II- Bright Giant

Type III- Normal Giant

Type IV- Sub-Giants

Type V- Main Sequence

Type VI- Sub-Dwarf

VII- White Dwarf

There is also Type 0, for hypergiants. However, these are exceedingly rare; examples include VY Canis Majoris, the Pistol Star, and R136a1.

Astrophysics Background
Recent changes to the rules have included more topics relating to basic astrophysics, including luminosity scales and relationships, temperature relationships, flux, and distance measures. A brief introduction to these topics is provided here. For a more in-depth study of astrophysics, please see the Astronomy page, but Reach for the Stars is unlikely to reach the level of complexity of the C Division event, so this would be mainly for enrichment purposes.

Radiation Laws
The radiation laws show relationships between stellar temperature, radius, and luminosity. Both Wien's Law and Stefan's Law are statements that show a proportion between different quantities, meaning that as one factor changes, the other factors will also change at a set rate. These are known as 'proportionality statements. These statements can be turned into equations by introducing a number that relates the different values numerically, known as a proportionality constant. At Division B it is unlikely that you will perform calculations with these laws, but general questions regarding these laws, such as the proportionality, may still be asked.

Note: in some of the following equations, the "proportional to" symbol, or [math]\propto[/math], is sometimes used. This means that the variables on each side of the equation are related proportionally to each other. However, it does not mean that the values are equal to each other; a proportionality constant needs to be added in order for this to be valid.

Wien's Law

Wien's displacement law states that the wavelength where a black-body (basically a perfect object that absorbs all radiation) emits most of its radiation is inversely proportional to the temperature. In other words, as the temperature of a star increases, the wavelength at which the star emits most of its radiation will get smaller. In astronomy, stars are often approximated as black-bodies in order to make solving problems easier. In variables, [math]\lambda_{max}\propto\frac1T[/math], where [math]{\lambda}_{max}[/math] is the wavelength of maximum output of radiation from an object and [math]T[/math] is Temperature. Based on this, if you multiply the wavelength by 2, the temperature would theoretically be divided by 2.

In order to use this as a normal equation, a proportional constant needs to be added. In this case, [math]b[/math] is used, which is called Wien's displacement constant. It is equal to [math]2900\mu m\cdot K[/math], resulting in the equation [math]\lambda_{max}=\frac{b}{T}[/math], where [math]\lambda_{max}[/math] is in micrometers and [math]T[/math] is in Kelvin. Using this form of the equation is highly unlikely to appear in RFTS, so check the Astronomy page for more details about this equation and examples.

Stefan-Boltzmann's Law

The Stefan-Boltzmann Law states that the total energy emitted from a black-body per unit surface area is proportional to the fourth power of its temperature. In equations, [math]j^*\propto T^4[/math] where [math]j^*[/math] is the total energy emitted per unit area and [math]T[/math] is Temperature. In this case, if the energy emitted per unit area is multiplied by 2, the temperature would have to increase by 2 to the fourth power, or 16.

For this equation, the proportional constant is the Stefan–Boltzmann constant, or [math]\sigma[/math]. It is equal to [math]5.67\cdot 10^{-8}\mathrm{W/m}^2\mathrm{K}^4[/math], and so the equation is [math]j^*=\sigma T^4[/math], where [math]j^*[/math] is in Watts per square meter, and [math]T[/math] is in Kelvin.

Since all black-bodies we encounter can be considered to be spheres, it has the surface area of a sphere, which is equal to [math]A=4\pi R^2[/math], where [math]R[/math] is the radius of the object. We can combine the equations by multiplying both sides of the relationship by [math]R^2[/math], since it is proportional to [math]A[/math], and since multiplying [math]j^*[/math] by [math]A[/math] gets the luminosity ([math]L[/math]), which is the total energy emitted from the star. Once all of this is done, the final proportion is: [math]L\propto R^2 T^4[/math]

So, what is important from this? Basically, in order for the luminosity to increase by a certain factor, the entire quantity of the radius squared times the temperature to the fourth power must also increase by that factor. It also explains that an increase in temperature will have much more of an effect on luminosity than an increase of the same factor in radius. The relationship is also important in that it is a good way to relate three of the main important variables in stellar physics.

When putting all of the constants back into the relationship to make it an equation again, it becomes [math]L=4\pi {R}^{2}\sigma {T}^{4}[/math], with [math]L[/math] in Watts, [math]R[/math] in meters, and [math]T[/math] in Kelvin. Again, questions requiring the use of this specific equation are beyond the scope of this event, and only the relationship itself is of primary importance. For more information about using the equation, check the Astronomy page.

Planck's Law

Planck's Law states that a hotter blackbody emits more energy at every frequency than a cooler blackbody. The equation form of the law is complicated, but on a radiance vs. temperature graph the curve for a hotter blackbody never dips below that of a cooler one.

Magnitude and Luminosity Scales
The luminosity of a celestial object refers to how much radiation (visible light, infrared, x-ray, etc.) it emits per unit time. Luminosity is measured in Joules per second or Watts. The luminosity, of the sun, for example, is [math]L_\odot=3.846\cdot 10^{26}[/math] watts. Magnitude scales are different methods to express luminosity.

Apparent Magnitude
The apparent magnitude, denoted by [math]m[/math], denotes the brightness of a celestial object as seen by an observer on Earth. The brighter an object appears, the lower its apparent magnitude. It is a logarithmic scale, not a linear scale, which means that a small decrease in magnitude results in a much greater increase in luminosity. For example, an object with apparent magnitude 5 less than that another would seems 100 times more luminous. Logarithms are very advanced for Division B, but at the very least, it is important to know that a small change in magnitude represents a much larger change in luminosity.

For example, the sun has apparent magnitude of -26.74, while Deneb has apparent magnitude of 1.2. Because of this, the sun seems [math]100^{(1.2+26.74)/5}\approx 150 \text{ billion}[/math] times brighter than Deneb! Apparent magnitude depends on both the luminosity of the object and its distance from Earth: while Deneb is more luminous than the sun, to an observer on Earth it is dimmer because it is farther away.

The system of apparent magnitude originated from Greece, where the brightest stars in the night sky were of first magnitude ([math]m=1[/math]), while the faintest to the naked eye were of sixth magnitude ([math]m=6[/math]). The system was formalized and extended beyond 1 to 6 in 1856 by N. R. Pogson.

Absolute Magnitude
The absolute magnitude, denoted by [math]M[/math], denotes the brightness of a celestial object as seen by an observer 10 parsecs (about 32.6 light years) away from the object. Similarly, an object with absolute magnitude 5 less that of another would be 100 times more luminous. The absolute magnitude is basically another way of expressing the luminosity of the object. Scientists often consider the absolute bolometric magnitude [math]M_b[/math] of an object, meaning that its radiation is being measured across all wavelengths.

For example, the sun has absolute magnitude 4.83, while Deneb has absolute magnitude -8.38. This means Deneb is [math]100^{(4.83+8.38)/5}\approx 440[/math] times more luminous than the sun. A typical Type Ia supernova has an absolute magnitude of about -19.3.

Inverse Square Law
The inverse square law says that a certain quantity is inversely proportional to the square of the distance relating to that quantity. In this case, "inversely proportional" means that an increase of one number causes a decrease in the other number. For example, suppose an astronomer measures a star of some intensity ([math]I_1[/math]) at a certain distance ([math]D[/math]) from the source. By the inverse square law, we have the following proportion: [math]I_1\propto \frac{1}{D^2}[/math]. This law also applies to Newton's Law of Gravitation. The law states that: [math]F=\frac{Gm_1 m_2}{r^2}[/math] where [math]m_1[/math] and [math]m_2[/math] are the masses of two objects, [math] r[/math] is the distance between the two objects, and [math]G[/math] is a special constant called Newton's gravitational constant. Since most objects in space are very far away from each other, the bottom part of the fraction is much larger than the top part of the fraction, so the law can be approximated for most far-apart objects by [math]F\approx\frac{1}{r^2}[/math].

The law also applies to the electrostatic force and the intensity of sound wave in a gas.

Distance Modulus
Distance modulus is a way to relate the absolute and apparent magnitudes of objects with the distance between them. The distance modulus equation is as follows: [math]m-M = 5\log_{10} (d) - 5, [/math] where [math]m[/math] is apparent magnitude, [math]M[/math] is the absolute magnitude, and [math]d[/math] being the distance to the object in parsecs. This equation uses a logarithm, which will more often than not be outside the scope of the Division B event, but for a brief tutorial on logarithms, please see this link. A different way of expressing this equation is: [math]d=10^{\frac{m-M+5}{5}}[/math]. For example, the Supernova SN 2011fe had peak apparent magnitude of [math]m=+9.9[/math], while its absolute magnitude is about [math]M=-19.3[/math]. Therefore, the supernova is [math]d=10^{\frac{9.9+19.3+5}{5}}\approx 7\text{ Mpc},[/math] away from Earth, close to the experimental value of [math]6.4\pm0.5\text{ Mpc}[/math].

This relationship can be found by using the laws that were discussed earlier. By the inverse square law, an observer 10 times as far as another from the same object would see the object as being 100 times less bright, and so they would mark it as having an apparent magnitude of 5 more than the other observer. Since absolute magnitude is the "apparent magnitude" of an observer 10 parsecs away, the first distance equation can be found by relating all of these factors. This is helpful to know in case theoretical questions are asked about the distance modulus relationship, but tests are unlikely to ask about the fine details for Reach for the Stars.

Galaxies
There are three main types of galaxies: Spiral, Elliptical, and Irregular. However, in the 2013 rules, there are no galaxies on the list. Nevertheless, galaxies are an important part of astronomy, so here is a brief background on the types of galaxies.

Spiral Galaxies


Spiral Galaxies are named so because they have prominent spiral arms and a central "galactic nucleus" or central bulge. Spiral Galaxies also have a very large rate of star formation in the spiral arms of the galaxy. Also, almost all spiral galaxies have a galactic halo that surrounds the galaxy. These halos contain stray stars and globular clusters. It is also theorized that many spiral galaxies have supermassive black holes at the center of the galaxy. Our own galaxy, The Milky Way, is a spiral galaxy, and is also theorized to have a supermassive black hole at its center, called Sgr A*. There is also a sub-division of spiral galaxies, known as barred-spiral galaxies. Barred-spirals have a central bar, and then have spiral arms shooting off at each end of the bar.

Spirals are classified by presence of a central bar and how tightly the rings are wound.

The spiral galaxies on the list for 2009 are:
 * M31 Andromeda Galaxy (in Andromeda)
 * M51 Whirlpool Galaxy (In Canes Venatica)
 * Milky Way Galaxy (Barred-Spiral)

Elliptical Galaxy
Elliptical Galaxies appear just like they sound- they are elliptical/ spherical. Elliptical Galaxies contain mostly old Population II stars, and also, they have a very low rate of star formation because there is barely any interstellar matter in elliptical galaxies. There is the least amount of Elliptical Galaxies in the known Universe. Also, they are classified by how spherical they are, with E followed by a number from zero to seven. Zero indicates perfectly spherical; seven indicates the extremely elongated and cigar-shaped.

The Elliptical Galaxies on the list for 2009 are:
 * M84 (in Virgo)

Concerning M84, some astronomers believe that it actually may be a Lenticular Galaxy (which is a half-way point between a Spiral galaxy and an Elliptical Galaxy)

Irregular Galaxies
Irregular also appear just how they sound- they are without a definite shape. They are normally formed by Spiral or Elliptical Galaxies that have been deformed by different forces- such as gravity. They contain a lot of interstellar matter. There are distinctions between "normal" irregular galaxies - with no hint of shape - and peculiar galaxies, that have some hint of form - usually, they were bent out of shape by outside forces or became violently active.

The Irregular Galaxies on the list for 2009 are:
 * Large Magellanic Cloud (in Dorado and Mensa)
 * Small Magellanic Cloud (in Tucana)

Sample Tests

 * Identification practice: [[Media: Reach for the Stars Practice Test.pdf|Reach for the Stars Test (2009)]]
 * RFTS Test and Pic Sheet for the test
 * Also be sure to check out the Reach for the Stars Test Exchange.

Useful Resources and Links

 * [[Media:rfts.pdf|An Example of a Reach For The Stars Study Sheet]]
 * [[Media:Reach_for_Stars_Guide_Sheet.pdf|Another Example of a Reach For the Stars Guide Sheet (2007)]]
 * Astronomy Today by Eric J. Chaisson
 * Another link
 * Foundations of Astronomy by Michael A. Seeds
 * Photo index of the Chandra Observatory (Good for DSOs)
 * STSCI Office of Public Outreach
 * New York Coaches Conference
 * Astronomy Picture of the Day
 * | Hertzsprung-russell diagram study
 * | Astronomy blog, by scioly.org's own AlphaTauri, syo_astro, and foreverphysics