Enjar Hertzsprung

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Richard Fuerst

Mr. Percival

DE Astronomy

2 March 2012

Ejnar Hertzsprung

            Born on October 8th, 1873, a young Dane would be lead away from the field of astronomy; ironically, he would become one of our greatest contributors to the study of stars, this astronomer was Ejnar Hertzsprung. Ejnar Hertzsprung's father, Severin Hertzsprung, had a graduate degree in astronomy but, for financial reasons, accepted a position in the Department of Finances; he advised his son against the financial insecurity of astronomy, therefore Ejnar opted for chemical engineering as a career path. After graduating from the Polytechnical Institute in Copenhagen in 1898 and spent several years as a chemist before he began to study photochemistry in Wilhelm Ostwald's laboratory. During this period he began talking with astronomer Karl Schwarzschild, and within a few years he joined Schwarzschild as senior staff astronomer at the observatory in Potsdam. By 1919 Hertzsprung was the associate director and associate professor of the University of Leiden, and in 1935 he became its director. Hertzsprung retired in 1944 and returned to Denmark, continuing his research until 1966. He died at 94, thirteen days after his birthday.

           

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            What made Ejnar Hertzsprung so important to astronomy? Two words: Hertzsprung-Russell diagram; Hertzsprung work with stars and luminosity yielded the means for determining stellar distances, galactic structures, and distances to other galactic systems. His unique background consisting of photometry and chemistry made him more qualified in the emerging field of spectrometry. Before Hertzsprung contributed to our understanding of the physical nature of stars, we only knew the radial velocities and the spectras of different stars. It was not until 1905 and 1907 that he showed the relationship between the sharp/deep features of absorption lines and a star's luminosity in his papers called Zur Strahlung der Sterne. We could now measure intrinsic brightness with stellar spectra! The Hertzsprung-Russell diagram relates the luminosity of stars with their temperature, so high temperature / luminosity stars occupy the top right and low temperature/ luminosity rest in the bottom left areas of the scatter plot. Most stars are main sequence stars and have a direct relationship between their temperature and absolute magnitude. There are some stars, which Hertzsprung alludes to in his papers, that do not necessary follow the temperature/luminosity relationship. For example, red giants are very luminous yet lack the higher temperatures of their blue giant counterparts. Hertzsprung research was the cornerstone of the later illustration that became the Hertzsprung-Russell diagram. One diagram he did create was one for the Pleiades star cluster in 1906; he also inferred that stars of the same cluster would be approximately the same distance away from Earth. He concluded that this distance was negligible! He also constructed a diagram for the Hyades using this principle. Hertzsprung came up with the method of obtaining distances for binary-star systems and different photographic methods to help gather data on stars. Altogether he made 36,000 estimates of the brightness of variable stars. Finally his determination of the distance to the Small

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Magellanic Cloud ,  the furthest distance determined for that time (10,000 parsecs), earned him the gold medal of the Royal Astronomy Society. 

Hertzsprung Biography Sources

Strand, K. Aa. "Hertzsprung." Concise Dictionary of Scientific Biography. By Charles Coulston Gillispie. Vol. 5. New York: Charles Scribner's Sons, 1981. 350-53. Print. American Council of Learned Societies.


Poulson, Erling. "Hertzsprung." RUNDETAARN. Rundetaarn, 24 Feb. 2012. Web. 24 Feb. 2012. <http://www.rundetaarn.dk/engelsk/observatorium/hertz.html>.

Question of the Day

Question to answer... How are stars formed and what evidence is there of their formation?

The study of star formation is ongoing; however, astronomers do have a theory with supporting evidence. When the Big Bang occurred 14 billion years ago it expelled hydrogen and helium. The gas molecules had mass, ergo they had gravity. Dense gas clusters began to collapse surrounding gases upon itself and grow in mass, eventually the resulting increase in temperature was enough to start nuclear fusion. By fusing hydrogen, heavier elements, like iron, started to enter our universe. Nuclear fusion, creation of heavier elements, and gravity all contributed to the formation of the earliest stars. On a side note, when stars use up all their "fuel" in their cores they slowly collapse upon themselves. Consequently, hotter, denser cores are formed and the outer layers of the star are pushed away, thereby cooling the outer layer. What happens next depends on the star's mass; however,  should the star happen to expel the rest of its matter, it shall be recycled by the universe and make new stars.

"Pillars of Creation"

-Observational Evidence-
+The Rossi X-Ray Timing Explorer has captured telltale X-Ray emissions of gas swirling just a few miles from the surface of a neutron star.
+  The Orion Nebula has young stars that are shaping the nebula to the pillars of dense gas that may be the homes of budding stars. The Eagle and Lagoon nebulae also show this.
+ Binary systems and planets hint that the same condensing gases made everything. Less massive formations became the smaller celestial objects that orbit the larger masses in out universe.

-Physics and Mathematical Evidence-
+ White Dwarfs do not collapse do to the pressure of fast-moving electrons, as dictated by quantum physics.
+ Gravity, nuclear fusion, solar wind, and the  Hertzsprung-Russel Diagram can be explained by what we know about the interaction of atoms, radiation, and the radius-luminosity-temperature relationship.
The Comments Section has the sources.

APOD 3.5

The Rosette Nebula
2012 February 14

In Monoceros there is a nebula that reminds lookers of flora here on Earth, the Rosette Nebula. It carries ionized hydrogen which allows us to see a reddish-hue in the visible spectrum. What is puzzling is why this large volume of gas and dust is not producing stars that are about the same size as its neighbor Orion. Regardless, the Unicorn in the nighttime sky has one of the most beautiful nebulae; the young hot stars radiate nicely in this stellar nursery.

Quarter #3/ Observations #2

Sunday Stargaze (2/12/12)

Location: School

Time: 7-9 P.M.

3 Planes and 2 satellites.

A clear, cold night tends to yield plenty of stars for observation, but the telescopes proved to be the most troublesome aspect in last night’s group stargaze. Different parts of the sky showed three different “seasons” simultaneously: winter in the east, fall in the west, and spring in the north. The south was mainly composed of Eridanus and Fornax with a two specks of bright light, Jupiter and Venus. The constellations in the east were more entertaining. Using Orion’s Betelgeuse, Canis Major’s Sirius, and Canis Minor’s Procyon we drew a “winter triangle” as a frame of reference. From that point we could find Monoceros, Gemini (Castor and Pollux), Lynx, Lepus, and Columba. In the north the Big Dipper was partly visible, and Cancer the Crab could be found a little to the northeast. The west had the Great Square of Pegasus, Cassiopeia, Cepheus, and Andromeda. Directly overhead was Taurus, Perseus, and Aries. Through the telescope we could see Aldebaren sitting in the V-shaped Hyades and the Pleiades with the binoculars. Additionally, Venus was waxing gibbous, Jupiter was in Aries, and in M42 there were four stars visible that formed the Trapezium.

APOD 3.4

Lunation
2012 February 5
Lunation is the mean time of one lunar phase cycle, about 29.5 days. The moon's side that faces Earth never changes, but the manner in which sunlight is reflected off it differs on a night to night basis. Lunar libration is the cause of the rocking motion observed in the moon. There are three different types of libration: longitude, latitude, and Diurnal. The changes in longitude are caused by the moon's elliptical orbit, and the changes in latitude are due to the moon's inclined axis of rotation; however, diurnal libation is caused by the observer's position shifting as the Earth rotates. These three characteristic all contribute to the perceived rocking motion of the moon.

APOD 3.3

The Helix Nebula from the VISTA Telescope
2012 January 31

My main reason for selecting this article was to better remember the Helix Nebula in Aquarius' miscellaneous section in COTW quizzes; details about the nebula will prevent me from forgetting to write it in. Details like the Helix Nebula's being the closest planetary nebula to Earth or that it actually looks like a helix (who would have guessed)! The nebula was created when the original star ,that produced the nebula, exhausted its nuclear fuel and expelled its gases to create a planetary nebula. The Helix Nebula is destined to be a White Dwarf Star one day, but for today we know the nebula as the Eye of God that resides in space. The name was popularized on the Internet when a May 2003 APOD took of picture of the nebula that ended up looking like a giant eye. Even though NASA never referred to it as the Eye of God, many websites titled the image on their respective sites as the Eye of God. On May. 4th, 2008 another "eye" was discovered, Kohoutek 4-55 planetary nebula, located in the constellation Cygnus. The Visible and Infrared Survey Telescope for Astronomy (VISTA) at the European Southern Observatory's Paranal Observatory in Chile took the above image and the following image is the Kohoutek "eye" photograph.