Lupus

Lupus is a constellation located in the deep southern sky. Its name is Latin for wolf. Lupus is bordered by six different constellations, although one of them (Hydra) merely touches at the corner. The other five are Scorpius (the scorpion), Norma (the right angle), Circinus (the compass), Libra (the balance scale), and Centaurus (the centaur). Covering 333.7 square degrees and 0.809% of the night sky, it ranks 46th of the 88 modern constellations. In the equatorial coordinate system, the right ascension coordinates of the constellation lie between 14h 17m 48.0635s and 16h 08m 36.6735s, while the declination coordinates are between −29.83° and −55.58°. The whole constellation is visible to observers south of latitude 34°N.

Lupus: Hevelius, Firmamentum, 1690

[http://www.constellationsofwords.com/Constellations/Lupus.htm]

In ancient times, the constellation was considered an asterism within Centaurus, and was considered to have been an arbitrary animal, killed, or about to be killed, on behalf of, or for, Centaurus. An alternative visualization, attested by Eratosthenes, saw this constellation as a wineskin held by Centaurus. It was not separated from Centaurus until Hipparchus of Bithynia named it Therion (meaning beast) in the 3rd century BCE. No particular animal was associated with it until the Latin translation of Ptolemy’s work identified it with the wolf.

The Greek constellation is probably based on the Babylonian figure known as the Mad Dog (UR.IDIM). This was a strange hybrid creature that combined the head and torso of a man with the legs and tail of a lion (the cuneiform sign ‘UR’ simply refers to a large carnivore; lions, wolves and dogs are all included). It is often found in association with the sun god and another mythical being called the Bison-man, which is supposedly related to the Greek constellation of Centaurus.

According to traditional Chinese uranography, the modern constellation Lupus is located within the eastern quadrant of the sky, which is symbolized as the Azure Dragon of the East (Dōng Fāng Qīng Lóng). The name of the western constellation in modern Chinese is ‘chái láng zuò,’ meaning ‘the ravenous wolf constellation.’

[https://en.wikipedia.org/wiki/Lupus_%28Chinese_astronomy%29]

[http://astropixels.com/constellations/charts/Lup.html]

[https://www.universetoday.com/131048/bright-binocular-nova-discovered-lupus/]

Overall, there are 127 stars within the constellation’s borders brighter than or equal to apparent magnitude 6.5. Most of the brightest stars in Lupus are massive members of the nearest OB association (loose star cluster), Scorpius-Centaurus.

The blue star is at the end of its main sequence stadium or is already done with it. Alpha Lupi, also known as Kakkab, is pulsating slightly with multiple periods.

[https://jumk.de/astronomie/big-stars/alpha-lupi.shtml]

Alpha Lupi is the brightest star in Lupus constellation. It has an apparent visual magnitude of 2.30 and is approximately 460 light years distant from Earth. It is a blue-white giant star with the stellar classification B1.5III. It is ten times more massive than the Sun and about 25,000 times more luminous. Alpha Lupi is classified as a Beta Cephei variable. It exhibits periodic variations in luminosity, by about 0.03, as a result of pulsations in the atmosphere. It has a period of 0.29585 days, which translates into about 7 hours and 6 minutes.

Beta Lupi is the second brightest star in the constellation. It has an apparent visual magnitude of 2.68 and is approximately 383 light years distant from Earth. The star can easily be seen without binoculars. Like Alpha Lupi, it is classified as a Beta Cephei variable. It is a multi-period variable, with a dominant period of 0.232 days. Beta Lupi is a blue-white giant belonging to the stellar class B2 III. It is believed to be about 25 million years old. The star has about 8.8 solar masses and a relatively high proper motion. It is located near the supernova remnant SN 1006.

Gamma Lupi is a blue-white subgiant star in Lupus. It is the third brightest star in Lupus. It belongs to the stellar class B2 IV. It has an apparent visual magnitude of 2.77 and is approximately 420 light years distant from the solar system. It is in fact a close binary system in which the primary component is itself a spectroscopic binary star, one that has an orbital period of 2.8081 days.

Delta Lupi is another blue-white subgiant with the stellar classification B1.5 IV. It has an apparent magnitude of 3.22 and is approximately 900 light years distant from the Sun. The star is about 10,000 times more luminous than the Sun and has 12 times the mass. It has a radius 6.1 times solar. The star is believed to be about 15 million years old. Delta Lupi is also classified as a Beta Cephei variable. It has a period of 0.1655 days, or six cycles per day.

Nu Lupi is a designation shared by two stars, Nu-1 Lupi and Nu-2 Lupi. Nu-1 Lupi is a yellow-white star halfway between the subgiant and giant evolutionary stage. It has the stellar classification of F6III-IV. The star has an apparent visual magnitude of 5.00 and is approximately 111 light years distant from the solar system. Nu-2 Lupi is a yellow main sequence star only 48.3 light years from Earth. It is very similar to the Sun, but has a significantly lower metallicity. Nu-2 Lupi has an abnormally high velocity. It has a mass 1.02 times solar and a radius 1.01 solar. It is 0.99 times as luminous as the Sun and has a rotational velocity of 2 km/s.

Three planets were discovered orbiting Nu-2 Lupi in September 2011. The innermost and outermost ones are super-Earths, with masses 5.28 and 9.59 times that of the Earth. Super-Earths are extrasolar planets that are more massive than Earth, but substantially less massive than the smaller gas giants in the solar system (Uranus and Neptune). The middle planet is too massive to be a super-Earth, with a mass 11.38 times that of our planet. All three planets orbit the star within 0.5 astronomical units, which means that they are likely too hot for life.

Lupus-TR-3 is a dim orange main sequence star in Lupus. It has an apparent magnitude of 17.4 and is approximately 8,950 light years distant from Earth. It has the stellar classification of K1V.

An exoplanet, Lupus-TR-3 b, was discovered in the star’s orbit in 2007. The planet has 0.81 times the mass of Jupiter and orbits the star with a period of 3.91405 days. It is the faintest transiting planet ever detected using ground-based methods (transit method).

[https://en.wikipedia.org/wiki/GQ_Lupi]

GQ Lupi is an orange main sequence star classified as a T Tauri variable. It has an apparent visual magnitude of 11.40 and is approximately 500 light years distant from Earth. The star has about 70 percent of the Sun’s mass and is less than 2 million years old. A substellar object, GQ Lupi b, was discovered orbiting the star in 2005. It was one of the first extrasolar planet candidates to be directly imaged.

[http://www.constellation-guide.com/constellation-list/lupus-constellation/]

NGC 5986

[https://en.wikipedia.org/wiki/NGC_5986]

Towards the north of the constellation are globular clusters NGC 5824 and NGC 5986, and close by the dark nebula B 228. To the south are two open clusters, NGC 5822 and NGC 5749, as well as globular cluster NGC 5927 on the eastern border with Norma.

On the western border are two spiral galaxies and the Wolf-Rayet planetary nebula IC 4406 containing some of the hottest stars in existence. IC 4406, also called the Retina Nebula, is a cylindrical nebula at a distance of 5,000 light-years:

The Retina Nebula

A dying star, IC 4406, dubbed the ‘Retina Nebula’ is revealed in this Hubble Heritage image. Like many other so-called planetary nebulae, IC 4406 exhibits a high degree of symmetry; the left and right halves of the Hubble image are nearly mirror images of the other. If we could fly around IC4406 in a starship, we would see that the gas and dust form a vast donut of material streaming outward from the dying star. From Earth, we are viewing the donut from the side. This side view allows us to see the intricate tendrils of dust that have been compared to the eye’s retina. In other planetary nebulae, like the Ring Nebula (NGC 6720), we view the donut from the top.

The donut of material confines the intense radiation coming from the remnant of the dying star. Gas on the inside of the donut is ionized by light from the central star and glows. Light from oxygen atoms is rendered blue in this image; hydrogen is shown as green, and nitrogen as red. The range of color in the final image shows the differences in concentration of these three gases in the nebula. Unseen in the Hubble image is a larger zone of neutral gas that is not emitting visible light, but which can be seen by radio telescopes.

One of the most interesting features of IC 4406 is the irregular lattice of dark lanes that criss-cross the center of the nebula. These lanes are about 160 astronomical units wide (1 astronomical unit is the distance between the Earth and Sun). They are located right at the boundary between the hot glowing gas that produces the visual light imaged here and the neutral gas seen with radio telescopes. We see the lanes in silhouette because they have a density of dust and gas that is a thousand times higher than the rest of the nebula. The dust lanes are like a rather open mesh veil that has been wrapped around the bright donut.

The fate of these dense knots of material is unknown. Will they survive the nebula’s expansion and become dark denizens of the space between the stars or simply dissipate?

[http://www.wolaver.org/Space/squarenebula.htm]

Another planetary nebula, NGC 5882, is towards the center of the constellation:

NGC 5882: A Small Planetary Nebula

Will most stars one day look like this? Pictured above is the planetary nebula NGC 5882, captured by the Hubble Space Telescope. Although planetary nebulae can appear similar to planets like Uranus and Neptune, they are actually gas clouds surrounding stars typically hundreds of light years away. Planetary nebula form when a typical star completes fusion in its core and ejects an outer envelope of gas - usually about 10 percent of the star’s initial mass. This gas shell dims in about 50,000 years- short compared to the lifetimes of stars. Therefore, although only about 1000 planetary nebula are known in our Galaxy, it is thought that most stars go through this phase. Green light is emitted when oxygen ions acquire electrons from the surrounding gas.

[http://apod.nasa.gov/apod/ap960828.html]

Lupus is also home to the historic supernova SN 1006, which has been described by various sources as appearing on April 30 to May 1, 1006:

SN 1006: X-Ray View of A Thousand-Year-Old Cosmic Tapestry

A new Chandra image of SN 1006 provides new details about the remains of an exploded star. This explosion was witnessed from Earth over a millennium ago. The Chandra data provides the best map to date of the debris field including information on important elements expanding into space. SN 1006 belongs to a class of supernova used to measure the expansion of the Universe.

This year, astronomers around the world have been celebrating the 50th anniversary of X-ray astronomy. Few objects better illustrate the progress of the field in the past half-century than the supernova remnant known as SN 1006.

When the object we now call SN 1006 first appeared on May 1, 1006 A.D., it was far brighter than Venus and visible during the daytime for weeks. Astronomers in China, Japan, Europe, and the Arab world all documented this spectacular sight. With the advent of the Space Age in the 1960s, scientists were able to launch instruments and detectors above Earth's atmosphere to observe the Universe in wavelengths that are blocked from the ground, including X-rays. SN 1006 was one of the faintest X-ray sources detected by the first generation of X-ray satellites.

A new image of SN 1006 from NASA’s Chandra X-ray Observatory reveals this supernova remnant in exquisite detail. By overlapping ten different pointings of Chandra’s field-of-view, astronomers have stitched together a cosmic tapestry of the debris field that was created when a white dwarf star exploded, sending its material hurtling into space. In this new Chandra image, low, medium, and higher-energy X-rays are colored red, green, and blue respectively.

The Chandra image provides new insight into the nature of SN1006, which is the remnant of a so-called Type Ia supernova . This class of supernova is caused when a white dwarf pulls too much mass from a companion star and explodes, or when two white dwarfs merge and explode. Understanding Type Ia supernovas is especially important because astronomers use observations of these explosions in distant galaxies as mileposts to mark the expansion of the Universe.

The new SN 1006 image represents the most spatially detailed map yet of the material ejected during a Type Ia supernova. By examining the different elements in the debris field- such as silicon, oxygen, and magnesium- the researchers may be able to piece together how the star looked before it exploded and the order that the layers of the star were ejected, and constrain theoretical models for the explosion.

Scientists are also able to study just how fast specific knots of material are moving away from the original explosion. The fastest knots are moving outward at almost eleven million miles per hour, while those in other areas are moving at a more leisurely seven million miles per hour. SN 1006 is located about 7,000 light years from Earth. The new Chandra image of SN 1006 contains over 8 days worth of observing time by the telescope. These results were presented at a meeting of High Energy Astrophysics Division of the American Astronomical Society in Monterey, CA.

[http://chandra.harvard.edu/photo/2013/sn1006/]

[https://en.wikipedia.org/wiki/Lupus_%28constellation%29]

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