Planets, Stars, and Galaxies

Observatory / Course Archives / ASTR 110 Fall 2019 / Vassallo

Kepler 186f

500 lightyears from Earth, in the constellation Cygnus, lives the star Kepler-186. The star is a Red Dwarf, the smallest, coolest type of star in the main sequence, that is about ½ the mass and size of the sun and has about 5% of the sun's luminosity. Around this star are orbiting 5 exoplanets, one of which has particular significance. Planets Kepler-186b, c, d, and e (which in this image can be seen lined up around and against the star), all orbit close to their host star, too close to be habitable. Kepler-186f, on the other hand, is different.

This exoplanet is far enough from its star that it lies in the habitable zone, the area far enough away that water may pool on the surface of the planet, as shown in this artist's concept image. Because of its distance it may also not be tidally locked. There is evidence that Kepler-186f could be a rocky terrestrial planet just like Earth. Also similar to our planet, Kepler-186f is close in size, being less than 10% larger than Earth. Its mass composition and density are unknown at this time, but it is known that the energy it receives from its host star is ⅓ compared to the Earth and Sun. Kepler-186f was discovered using the transit method (measuring how much starlight is blocked when the planet passes in front of its star) by Elisa Quintana at the Kepler Space Observatory on April 17th, 2014.

Carina Nebula

January 25th, 1752, the Carina Nebula was discovered by Nicolas-Louis de Lacaille. The Carina Nebula is located in the Sagittarius-Carina arm of the Milky Way, 7,500 lightyears from Earth. It is home to 10 total star clusters and hosts many areas with new star formation, being described as a stellar nursery. The Chandra X-Ray Observatory numbers more than 14,000 stars in the Carina Nebula. Cavities filled with stellar winds and ultraviolet radiation compress against cold hydrogen and prompt the creation of new stars. In the image, you can see the clouds of dust and gas being swirled across space, speckled with clusters of bright stars.

The Carina Nebula also is home to some significant stellar objects. One of the most notable is Eta Carinae, a hypergiant star with a mass and luminosity that far surpasses those of the Sun. Due to its size and location, it is one of the most massive stars we can study right now. In Eta Carinae, you can see dark globules, areas that contain small, isolated, dark nebulae which contain dense gas and dust where new stars may form. The Carina Nebula is sometimes referred to as the "nebula that contains the keyhole," referring to the aptly named stellar object, the . This is a small dark cloud of dust and cold molecules, mixed in with hot fluorescing gas. Over time its appearance has changed, possibly because of the ionizing radiation that comes from the massive Eta Carinae. Close to Eta Carinae is the Homunculus Nebula, a relatively smaller formation that is thought to have come from an ejection in 1841. This nebula absorbs light from the surrounding central area and re-emits it as infrared light. In the Carina Nebula, there is a distinct stellar object formed from pillars of dust and gas. The Mystic Mountain gives us evidence that new stars are being formed due to the hot jets of gas that come from the main formation, which is shot out because of these high energy baby stars. Those are just a few of the brilliant stellar objects you can find in the busy region of the Carina Nebula.

Messier 82

In the constellation Ursa Major, lies the galaxy Messier 82, also known as the Cigar Galaxy, 12 million lightyears away. It was discovered on December 31st, 1774 by Johann Elert Bode then rediscovered in 1779 by Pierre Mechain. While originally thought to be an irregular galaxy (most likely due to its incredibly bright inner disk), M82 is actually a spiral galaxy, with two arms that were detected in the infrared. Looking at this image compiled by three of the top observatories, you can see the different colors captured by different methods. The red in the image shows sulfur and was captured in infrared, the blue comes from X-Ray data and also depicts oxygen, orange is hydrogen emission in this particular image, and the yellow-green colors show visible light wavelengths.

M82 is 5 times more luminous than the entire Milky Way and has a much higher, about 10 times, rate of star formation, the latter being the reason it is also a starburst galaxy. You can even see the gas from the forming of new stars being shot out from the star's core. This abnormally high rate of star formation is believed to come from M82's very close neighbor M81. Because of the intense amount of star formation, M82, when viewed in infrared, is the brightest galaxy in the sky. You can see both M81 and M82 through binoculars and small telescopes and, due to the position of our home galaxy, the Milky Way, the best time to view these galaxies is springtime.