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Katherine Johnson’s mathematical calculations helped guide some of America’s most important early space missions while she confronted the racial and gender barriers faced by Black women in twentieth-century America.
MORE →Reflects the personal views, recollections, and perspective of the author, Mike Davis.
This is a personal recollection on the Move fire on May 13, 1985
| Nebula | |
|---|---|
 Corona Australis Molecular Cloud imaged by DECam | |
| Observation data: J2000.0 epoch | |
| Right ascension | 19h 01m 51s[1] |
| Declination | –36° 58.9′[1] |
| Distance | 425 ly (130 pc) |
| Apparent dimensions (V) | 16.0° × 6.5° |
| Constellation | Corona Australis |
| Physical characteristics | |
| Radius | 8 ly |
| Designations | CrA Dark Cloud, CrA MCLD, CrA region |
The Corona Australis molecular cloud, located at a distance of 130 parsecs (~430 ly),[2][3] is a dark nebula of gas and dust and is one of the nearest star formation regions from Earth.[4] Sometimes referred to as the CrA Dark Cloud or the CrA Cloud, it hosts several reflection nebulae − NGC 6729, NGC 6726/6727, and IC 4812 being the most notable.[5] The globular cluster known as NGC 6723, which appears close by, is actually 29,000ly away, and so not part of the region.[6] The cloud is located in the constellation Corona Australis, close to the border with Sagittarius, between Gamma Coronae Australis and Epsilon Coronae Australis and stretches roughly 8ly across.
The cloud is located at about 18% below the galactic plane and covers an angular area of 16.0° × 6.5° on the celestial sphere.[4] Temperatures of the cloud ranges from 13–22 K, and there is a total of about 7,000 times the mass of the Sun in material. Over half of the mass of the complex is concentrated around a small area, and this is the most active star-forming region. There are embedded infrared sources within the complex. A total of 425 infrared sources have been detected near the L1688 cloud. These are presumed to be young stellar objects, including 16 classified as protostars, 123 T Tauri stars with dense circumstellar disks, and 77 weaker T Tauri stars with thinner disks. The last two categories of stars have estimated ages ranging from 100,000 to a million years.
Known to exhibit significant extinction, as high as 45 magnitudes at visual wavelengths (AV~45 mag), astronomers have identified 55 distinct optical members within the CrA Cloud as of 2008[update].[4] At the core is the Coronet protostar cluster, a loose collection of about 30 young stars with a wide range of masses at various stages of evolution.[7] Surrounding the cluster are a few late stage B stars, numerous Herbig–Haro objects, and several YSOs. At the opposite end of the mass spectrum, are two confirmed brown dwarfs along with seven more candidates.[8] There are also many embedded infrared sources within the complex. The molecular cloud has been most widely surveyed in the infrared, X-rays, radio waves and in the millimeter continuum.
In the north of the constellation is the Corona Australis Molecular Cloud, a dark molecular cloud with many embedded reflection nebulae, including NGC 6729, NGC 6726–7, and IC 4812. A star-forming region of around 7000 M☉,[9] it contains Herbig–Haro objects, T Tauri stars with dense circumstellar disks, (protostars) and some very young stars.[10] Located about 430 light years (130 parsecs) away, it is one of the closest star-forming regions to our solar system.[11] The related NGC 6726 and 6727, along with unrelated NGC 6729, were first recorded by Johann Friedrich Julius Schmidt in 1865.[12]
![The R CrA region at the heart of the CrA Dark Cloud.[13][14][15]](viewer.php?source=wikipedia&q=File%3AR%20Coronae%20Australis%20region.jpg&result=0#selected-result)
![Star-forming region NGC 6729 showing the dramatic birth of very young stars.[16]](viewer.php?source=wikipedia&q=File%3ANGC%206729.jpg&result=0#selected-result)
Media related to Corona Australis Molecular Cloud at Wikimedia Commons
Source: Wikipedia. Article content is retrieved live through the MediaWiki API.
Epsilon Tauri or ε Tauri, formally named Ain (), is an orange giant star located approximately 146 light-years (45 parsecs) from the Sun in the constellation of Taurus. An exoplanet (designated Epsilon Tauri b, later named Amateru) is believed to be orbiting the star. It is a member of the Hyades open cluster. As such its age is well constrained at 625 million years. It is claimed to be the heaviest among planet-harboring stars with reliable initial masses. Given its large mass, this star, though presently of spectral type K0 III, was formerly of spectral type A that has now evolved off the main sequence into the giant phase. It is regarded as a red clump giant; that is, a core-helium burning star. Since Epsilon Tauri lies near the plane of the ecliptic, it is sometimes occulted by the Moon and (very rarely) by planets. It has an 11th magnitude companion 182 arcseconds away, although this is an unrelated background star.
Epsilon Tauri b (abbreviated ε Tauri b or ε Tau b), formally named Amateru , is a super-Jupiter exoplanet orbiting the K-type giant star Epsilon Tauri approximately 146 light-years (45 parsecs) away from the Earth in the constellation of Taurus. It orbits the star further out than Earth orbits the Sun. It has moderate eccentricity. The planet orbits one of the four giant stars in the Hyades star cluster, and was the first planet ever discovered in an open cluster.
The Hyades (; Greek: Ὑάδες; also known as Caldwell 41, Collinder 50, or Melotte 25) is the nearest open cluster and one of the best-studied star clusters. Located about 153 light-years (47 parsecs) away from the Sun, it consists of a roughly spherical group of hundreds of stars sharing the same age, place of origin, chemical characteristics, and motion through space. From the perspective of observers on Earth, the Hyades Cluster appears in the constellation Taurus, where its brightest stars form a "V" shape along with the still-brighter Aldebaran. However, Aldebaran is unrelated to the Hyades, as it is located much closer to Earth (65 light-years) and merely happens to lie along the same line of sight. The moving group CWNU 1242 also shares the line of sight to the Hyades, but is likewise not associated with the Hyades, being 949 light-years away. The five brightest member stars of the Hyades have consumed the hydrogen fuel at their cores and have evolved into giant stars. Together with Aldebaran, four of these stars, Gamma, Delta1, Epsilon, and Theta2 Tauri, form an asterism that is traditionally identified as the head of Taurus the Bull. The fifth of the giants is Theta1 Tauri, a tight naked-eye companion to the brighter Theta2 Tauri. Epsilon Tauri, known as Ain (the "Bull's Eye"), has a gas giant exoplanet candidate, the first planet to be found in any open cluster. The age of the Hyades is estimated to be about 625 million years. The core of the cluster, where stars are the most densely packed, has a radius of 8.8 light-years (2.7 parsecs), and the cluster's tidal radius – where the stars become more strongly influenced by the gravity of the surrounding Milky Way galaxy – is 33 light-years (10 parsecs). However, about one-third of confirmed member stars have been observed well outside the latter boundary, in the cluster's extended halo; these stars are probably in the process of escaping from its gravitational influence.
The Corona Australis molecular cloud, located at a distance of 130 parsecs (~430 ly), is a dark nebula of gas and dust and is one of the nearest star formation regions from Earth. Sometimes referred to as the CrA Dark Cloud or the CrA Cloud, it hosts several reflection nebulae − NGC 6729, NGC 6726/6727, and IC 4812 being the most notable. The globular cluster known as NGC 6723, which appears close by, is actually 29,000ly away, and so not part of the region. The cloud is located in the constellation Corona Australis, close to the border with Sagittarius, between Gamma Coronae Australis and Epsilon Coronae Australis and stretches roughly 8ly across. The cloud is located at about 18% below the galactic plane and covers an angular area of 16.0° × 6.5° on the celestial sphere. Temperatures of the cloud ranges from 13–22 K, and there is a total of about 7,000 times the mass of the Sun in material. Over half of the mass of the complex is concentrated around a small area, and this is the most active star-forming region. There are embedded infrared sources within the complex. A total of 425 infrared sources have been detected near the L1688 cloud. These are presumed to be young stellar objects, including 16 classified as protostars, 123 T Tauri stars with dense circumstellar disks, and 77 weaker T Tauri stars with thinner disks. The last two categories of stars have estimated ages ranging from 100,000 to a million years. Known to exhibit significant extinction, as high as 45 magnitudes at visual wavelengths (AV~45 mag), astronomers have identified 55 distinct optical members within the CrA Cloud as of 2008. At the core is the Coronet protostar cluster, a loose collection of about 30 young stars with a wide range of masses at various stages of evolution. Surrounding the cluster are a few late stage B stars, numerous Herbig–Haro objects, and several YSOs. At the opposite end of the mass spectrum, are two confirmed brown dwarfs along with seven more candidates. There are also many embedded infrared sources within the complex. The molecular cloud has been most widely surveyed in the infrared, X-rays, radio waves and in the millimeter continuum.
Before the 1921 destruction of Tulsa’s Greenwood District, Black residents had created a remarkable center of business and community life. The district included stores, professional offices, entertainment venues and homes owned by Black citizens. Understanding Greenwood means learning what was built—not only what was burned.
MORE →Shirley Chisholm, elected in 1968.