Lynx

[http://www.redorbit.com/reference/lynx_constellation/]

Lynx, named after the animal, is a constellation in the northern sky. This constellation is mostly very faint, with its brightest stars forming a zigzag line. Lynx is bordered by Camelopardalis to the north, Auriga to the west, Gemini to the southwest, Cancer to the south, Leo to the east and Ursa Major to the northeast. Covering 545.4 square degrees and 1.322% of the night sky, it ranks 28th of the 88 constellations in size. In the equatorial coordinate system, the right ascension coordinates of the constellation lie between 06h 16m 13.76s and 09h 42m 50.22s, while the declination coordinates are between +32.97° and +61.96°. On dark nights, the brighter stars can be seen as a crooked line extending roughly between Camelopardalis and Leo, and north of the bright star Castor. Lynx is most readily observed from the late winter to late summer to northern hemisphere observers, culminating at midnight on 20 January. The whole constellation is visible to observers north of latitude 28°S.

Johannes Hevelius is credited with the creation of this constellation saying that anyone wishing to study the stars in this area would need the eyes of a Lynx.

[http://umich.edu/~lowbrows/guide/lynx.html]

Polish astronomer Johannes Hevelius formed the constellation in the 17th century from 19 faint stars that he observed with the unaided eye between the constellations Ursa Major and Auriga. Naming it Lynx because of its faintness, he challenged future stargazers to see it, declaring that only the lynx-eyed (those of good sight) would have been able to recognize it. Hevelius gave it the alternate name of Tiger in his catalogue as well as Lynx, but kept the latter name only in his atlas. John Flamsteed adopted the constellation in his catalogue and atlas. According to amateur astronomer Richard Hinckley Allen, the chief stars in Lynx ‘might well have been utilized by the modern constructor, whoever he was, of our Ursa Major to complete the quartette of feet.’

[http://www.dibonsmith.com/lyn_con.htm]

Francis Baily gave a single star a Bayer designation- Alpha Lyncis- while Flamsteed numbered 44 stars, though several lie across the boundary in Ursa Major. Overall, there are 97 stars within the constellation’s borders brighter than or equal to apparent magnitude 6.5.

Alpha Lyncis is the brightest star in the northern constellation of Lynx with an apparent magnitude of +3.13. Unusually, it is the only star in the constellation that has a Bayer designation. Based upon parallax measurements, this star is located about 203 light-years (62 parsecs) from the Earth.

This is a giant star that has exhausted the hydrogen at its core and has evolved away from the main sequence. It has expanded to about 55 times the Sun’s radius and it is emitting roughly 673 times the luminosity of the Sun. The estimated effective temperature of the star’s outer envelope is 3,882 K, which is lower than the Sun's effective temperature of 5,778 K, and is giving Alpha Lyncis an orange hue that is characteristic of K-type stars.

Alpha Lyncis is a suspected small-amplitude red variable star that changes apparent magnitude from +3.17 up to +3.12. This variability pattern typically occurs in stars that have developed an inert carbon core surrounded by a helium-fusing shell, and suggests that Alpha Lyncis is starting to evolve into a Mira-type variable.

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

Lynx is rich in double stars. The second brightest star in the constellation is 38 Lyncis at magnitude 3.8. When viewed through a moderate telescope, the two components- a brighter blue-white star of magnitude 3.9 and a fainter star of magnitude 6.1 that has been described as lilac as well as blue-white- can be seen.

10 Ursae Majoris is the third brightest star in Lynx. Originally in the neighboring constellation Ursa Major, it became part of Lynx with the official laying down of the constellation borders. Appearing to be of magnitude 3.97, it can be split by a telescope to reveal a yellow-white main sequence star of spectral type F4V of magnitude 4.11 and a star very similar to the Sun of spectral class G5V and magnitude 6.18. The two are 10.6 au apart and orbit each other every 21.78 years. The system is about 53 light-years distant from Earth.

The red supergiant Y Lyncis is a popular target among amateur astronomers, as it is a semiregular variable ranging in brightness from magnitude 6.2 to 8.9. Its changes in brightness are complex, with a shorter period of 110 days due to the star’s pulsations, and a longer period of 1400 days possibly due to the star's rotation or convectively induced oscillatory thermal (COT) mode. It has an estimated diameter around 580 times that of the Sun, is around 1.5 to 2 times as massive, and has a luminosity around 25,000 times that of the Sun.

The only named star is Alsciaukat (from the Arabic for thorn), also known as 31 Lyncis, located about 380 light-years distant. It is also an evolved giant star around twice the Sun’s mass that has swollen and cooled since exhausting its core hydrogen. It is anywhere from 59 to 75 times as wide as the Sun, and 740 times as luminous.

Six star systems have been found to contain exoplanets. 6 Lyncis is an orange subgiant that spent much of its life as an A-type or F-type main sequence star. It is orbited by a planet with a minimum mass of 2.4 Jupiter masses and period of 899 days.

HD 75898 is a yellow subgiant that has a planet 2.51 Jupiter masses orbiting with a period of around 418 days.

Three star systems were found to have planets that were observed as they passed in front of them by the XO Telescope in Hawaii. XO-2 is a binary star system, both the stars of which are slightly less massive and cooler than the Sun and have planetary companions: XO-2S has a Saturn-mass planet at 0.13 au distance with a period of around 18 days, and one a little more massive than Jupiter at a distance of 0.48 au and with a period of around 120 days, while XO-2N has a hot Jupiter with around half Jupiter’s mass that has an orbit of only 2.6 days.

XO-4 is an F-type main sequence star that is a little hotter and more massive than the Sun that has a hot Jupiter orbiting with a period of around 4.1 days.

XO-5 is a Sun-like star with a hot jupiter about as massive as Jupiter that takes around 4.2 days to complete an orbit.

Size comparison of WASP-13b with Jupiter

WASP-13 is a sunlike G-type star located in the Lynx constellation. The star’s mass is estimated at 1.09 times the mass of the Sun, its radius at 1.559 times that of the Sun, and its density at 0.288 time's the Sun’s density. The star’s metallicity, which is measured by iron content, is placed roughly at [Fe/H] = 0, similar to that of the Sun. Also, the star’s estimated effective temperature is 5826 K, slightly warmer than the Sun. WASP-13 has an apparent magnitude of 10.42, making it invisible to the unaided eye as seen from Earth.

WASP-13b is an extrasolar planet that was discovered in 2008 in the orbit of the sunlike star WASP-13. The planet has a mass of nearly half that of Jupiter, but a radius five-fourths the size of Jupiter. This low relative mass might be caused by a core that is of low mass or that is not present at all.

The planet orbits at approximately 5% of the distance between the Sun and Earth every four days. The star was observed several times between 2006 and 2009, at first through the SuperWASP program and later through focused follow-up observations.

[https://en.wikipedia.org/wiki/WASP-13b]

Lynx’s most notable deep sky object is NGC 2419, also called the ‘Intergalactic Wanderer’ as it was assumed to lie outside the Milky Way. At a distance of between 275,000 and 300,000 light-years from Earth, it is one of the most distant known globular clusters within our galaxy. NGC 2419 is likely in a highly elliptical orbit around the Milky Way. It has a magnitude of 10.3 and is a Shapley class II cluster; this classification indicates that it is extremely concentrated at its center. Originally thought to be a star, NGC 2419 was discovered to be a globular cluster by American astronomer Carl Lampland:

NGC 2419: Intergalactic Wanderer

Three objects stand out in this thoughtful telescopic image, a view toward the mostly stealthy constellation Lynx. The two brightest (the spiky ones) are nearby stars. The third is the remote globular star cluster NGC 2419, at distance of nearly 300,000 light-years. NGC 2419 is sometimes called ‘the Intergalactic Wanderer,’ an appropriate title considering that the distance to the Milky Way’s satellite galaxy, the Large Magellanic Cloud, is only about 160,000 light-years. Roughly similar to other large globular star clusters like Omega Centauri, NGC 2419 is itself intrinsically bright, but appears faint because it is so far away. NGC 2419 may really have an extragalactic origin as, for example, the remains of a small galaxy captured and disrupted by the Milky Way. But its extreme distance makes it difficult to study and compare its properties with other globular clusters that roam the halo of our Milky Way galaxy.

[https://apod.nasa.gov/apod/ap150604.html]

NGC 2683 is an unbarred spiral galaxy in Lynx. It appears nearly edge-on when observed from Earth. The galaxy has a visual magnitude of 10.6 and is about 25 million light years distant. The Astronaut Memorial Planetarium and Observatory site gave it the nickname the ‘UFO galaxy.’ The galaxy was discovered by William Herschel in February 1788. It is moving away from Earth at the speed of 410 km/s and from the galactic center at 375 km/s:

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

Hubble spies a UFO

The NASA/ESA Hubble Space Telescope has spotted a UFO- well, the UFO Galaxy, to be precise. NGC 2683 is a spiral galaxy seen almost edge-on, giving it the shape of a classic science fiction spaceship. This is why the astronomers at the Astronaut Memorial Planetarium and Observatory gave it this attention-grabbing nickname.

While a bird’s eye view lets us see the detailed structure of a galaxy (such as this Hubble image of a barred spiral), a side-on view has its own perks. In particular, it gives astronomers a great opportunity to see the delicate dusty lanes of the spiral arms silhouetted against the golden haze of the galaxy’s core. In addition, brilliant clusters of young blue stars shine scattered throughout the disc, mapping the galaxy’s star-forming regions.

Perhaps surprisingly, side-on views of galaxies like this one do not prevent astronomers from deducing their structures. Studies of the properties of the light coming from NGC 2683 suggest that this is a barred spiral galaxy, even though the angle we see it at does not let us see this directly.

NGC 2683, discovered on 5 February 1788 by the famous astronomer William Herschel, lies in the Northern constellation of Lynx. A constellation named not because of its resemblance to the feline animal, but because it is fairly faint, requiring the “sensitive eyes of a cat” to discern it. And when you manage to get a look at it, you’ll find treasures like this, making it well worth the effort.

This image is produced from two adjacent fields observed in visible and infrared light by Hubble’s Advanced Camera for Surveys. A narrow strip which appears slightly blurred and crosses most the image horizontally is a result of a gap between Hubble’s detectors. This strip has been patched using images from observations of the galaxy made by ground-based telescopes, which show significantly less detail.

The field of view is approximately 6.5 by 3.3 arcminutes.

[https://www.spacetelescope.org/images/potw1213a/]

NGC 2770 is a type SASc spiral galaxy located about 88 million light-years away that has hosted three Type Ib supernovae: SN 1999eh, SN 2007uy, and SN 2008D. The last of these is famous for being the first supernova detected by the X-Rays released very early on in its formation, rather than by the optical light emitted during later stages, which allowed the first moments of the outburst to be observed. It is possible that NGC 2770’s interactions with a suspected companion galaxy may have created the massive stars causing this activity:

Supernova Factory NGC 2770

The stellar explosions known as supernovae are among the most powerful events in the universe. Triggered by the collapsing core of a massive star or the nuclear demise of a white dwarf, supernovae occur in average spiral galaxies only about once every century. But the remarkable spiral galaxy NGC 2770 has lately produced more than its fair share. Two still bright supernovae and the location of a third, originally spotted in 1999 but now faded from view, are indicated in this image of the edge-on spiral. All three supernovae are now thought to be of the core-collapse variety, but the most recent of the trio, SN2008D, was first detected by the Swift satellite at more extreme energies as an X-ray flash (XRF) or possibly a low-energy version of a gamma-ray burst on January 9th. Located a mere 90 million light-years away in the northern constellation Lynx, NGC 2770 is now the closest galaxy known to host such a powerful supernova event.

[http://apod.nasa.gov/apod/ap080118.html]

APM 08279+5255 is a very distant, broad absorption line quasar discovered in 1998 and initially considered the most luminous object yet found. It is magnified and split into multiple images by the gravitational lensing effect of a foreground galaxy through which its light passes. It appears to be a giant elliptical galaxy with a supermassive black hole around 23 billion times as massive as the Sun and an associated accretion disk that has a diameter of 3600 light years. The galaxy possesses large regions of hot dust and molecular gas, as well as regions with starburst activity. It has a cosmological redshift of 3.911:

This artist’s concept illustrates a quasar, or feeding black hole, similar to APM 08279+5255, where astronomers discovered huge amounts of water vapor.

Two teams of astronomers have discovered the largest and farthest reservoir of water ever detected in the universe. The water, equivalent to 140 trillion times all the water in the world’s ocean, surrounds a huge, feeding black hole, called a quasar, more than 12 billion light-years away.

“The environment around this quasar is very unique in that it’s producing this huge mass of water,” said Matt Bradford, a scientist at NASA’s Jet Propulsion Laboratory in Pasadena, Calif. “It’s another demonstration that water is pervasive throughout the universe, even at the very earliest times.” Bradford leads one of the teams that made the discovery.

A quasar is powered by an enormous black hole that steadily consumes a surrounding disk of gas and dust. As it eats, the quasar spews out huge amounts of energy. Both groups of astronomers studied a particular quasar called APM 08279+5255, which harbors a black hole 20 billion times more massive than the sun and produces as much energy as a thousand trillion suns.

Astronomers expected water vapor to be present even in the early, distant universe, but had not detected it this far away before. There’s water vapor in the Milky Way, although the total amount is 4,000 times less than in the quasar, because most of the Milky Way’s water is frozen in ice.

Water vapor is an important trace gas that reveals the nature of the quasar. In this particular quasar, the water vapor is distributed around the black hole in a gaseous region spanning hundreds of light-years in size (a light-year is about six trillion miles). Its presence indicates that the quasar is bathing the gas in X-rays and infrared radiation, and that the gas is unusually warm and dense by astronomical standards. Although the gas is at a chilly minus 63 degrees Fahrenheit (minus 53 degrees Celsius) and is 300 trillion times less dense than Earth's atmosphere, it's still five times hotter and 10 to 100 times denser than what's typical in galaxies like the Milky Way.

Measurements of the water vapor and of other molecules, such as carbon monoxide, suggest there is enough gas to feed the black hole until it grows to about six times its size. Whether this will happen is not clear, the astronomers say, since some of the gas may end up condensing into stars or might be ejected from the quasar.

Bradford’s team made their observations starting in 2008, using an instrument called ‘Z-Spec’ at the California Institute of Technology’s Submillimeter Observatory, a 33-foot (10-meter) telescope near the summit of Mauna Kea in Hawaii. Follow-up observations were made with the Combined Array for Research in Millimeter-Wave Astronomy (CARMA), an array of radio dishes in the Inyo Mountains of Southern California. 

[https://www.nasa.gov/topics/universe/features/universe20110722.html]

The Lynx Arc is located in the constellation Lynx, 12 billion light years away (z=3.357) from Earth, 8 million times farther away and one million times brighter than the Orion Nebula. It contains about 1 million blue stars, while the Orion Nebula only contains 4.

It was found in a systematic search around galaxy cluster RX J0848+4456 (z=0.570), with the help of a gravitational lens, a 4.5 billion light years distant galaxy cluster (CL J0848.8+4455 lying at z=0.543). Amongst others the Keck Observatory, the Hubble Space Telescope and ROSAT participated in the search. It was discovered in 2003 and is considered to be the hottest known star-birthing region in the Universe as of October 2003. It is located at 08h 48m 48.76s +44° 55′ 49.6″:

Located behind a cluster of galaxies in northern constellation Lynx around 12 billion light-years (ly) away, the Lynx Arc is a distant supercluster of extremely hot, young stars. Roughly one million times brighter than the well-known Orion Nebula, the Lynx Arc contains a million blue stars that are twice as hot as similar stars in the Milky Way galaxy. Only visible through gravitational lensing by a closer cluster of galaxies, the Arc is a feature of the early days of the universe, when ‘furious firestorms of star birth’ were more common. It may be going through a short-lived luminous phase that may have lasted for as little as a few million years.

Within constellation Lynx, the very young supercluster was found in an image of the Lynx galaxy cluster, located within the center box.

The Arc was discovered during a systematic study of distant galaxy clusters using major X-ray, optical, and infrared telescopes. An international team of astronomers found the stretched and magnified image of a huge cluster of stars appearing as a red arc behind the already distant, Lynx galaxy double cluster of CL J0848.8+4455 (z=0.543) and RX J0848+4456 (z=0.570), which are located around 5.4 billion light-years away in northern constellation Lynx. The Arc was eventually determined to be located about 12 billion light-years away (at a redshift of z=3.357).

The young supercluster is visible as a red object located to the right of the Lynx cluster of galaxies, within the boxed area.

Although the largest known star-birth clusters in the Milky Way are the Arches clusters in the galactic center, the Carina Nebula in the Constellation Fornax, and the 30 Doradus cluster in the Large Magellanic Cloud, these clusters contain only hundreds or thousands of super-hot stars, only a fraction of the size of the Lynx Arc megacluster.

The reddish arc is really a stretched and magnified image of a distant mega-cluster of stars lying far behind the Lynx galaxy cluster about 12 billion light-year away.

Analysis of the color and intensity of light from the Arc indicates that much of its light started out as ultraviolet light from the hottest stars and was stretched to red light (‘red-shifted’) after travelling 12 billion light-years. As the hotter a star is, the bluer and more massive it is, and so the intensity of the ultraviolet radiation emitted suggests that the stars of the Lynx Arc are among the most massive stars seen ever detected in the universe. The spectrum of the Arc suggests that its stars are more than twice as hot as the Orion Nebula’s central stars, with surface temperatures up to 144,000 degrees Fahrenheit (80,000 degrees Celsius)- hotter and brighter than Theta1 Orionis C (of spectral and luminosity type O7 V), the brightest of the four central stars of the Trapezium Cluster in Orion. Although there are larger and brighter star-forming regions than the Orion Nebula in the nearby universe, none are as bright as the Lynx arc, nor do they contain such large numbers of hot stars. Even the most massive, normal nearby stars are no hotter than around 72,000 degrees Fahrenheit (40,000 degrees Celsius). However, stars formed from primordial clouds of extemely metal-poor, hydrogen and helium gas in the early universe can be more massive and consequently much hotter than those created today- perhaps up to 215,000 degrees Fahrenheit (120,000 degrees Celsius).

Hotter than Theta1 Orionis C, the brightest of the four central stars of the Trapezium Cluster in Orion (at left), the bright O-type stars of the Lynx Arc were brighter and bluer than any of the stars of the ‘Solar neighborhood’ known to be located within 100 light-years of Sol.

Although many of the first generation of stars (Population III) in the cosmos may each have been as much as several hundred Solar-masses, but the comparatively metal-rich, chemical makeup of the universe today prevents stars from forming beyond about 100 Solar-masses. Such ‘primordial’ super-hot stars are thought to be the first luminous objects to condense after the Big Bang cooled. Astronomers believe that these first stars formed considerably earlier than those observed in the Lynx Arc- up to 1.8 billion years earlier. While the nebular material around the Arc is not extremely metal-poor, there is considerable evidence that the ionizing stellar cluster is considerably more metal-poor. The apparent overabundance of silicon in the nebula of the star cluster could indicate enrichment by past ‘pair-instability supernovae.’ Because the stars of the Lynx Arc were also very massive, however, most probably exploded as supernovae within a few million years or so, to blast their own, newly created stock of heavy elements into intergalactic space. Some of this material was recycled into subsequent generations of stars, while surviving stars may have coalesced with other clusters to form the earliest galaxies.

[http://www.solstation.com/x-objects/lynx-arc.htm]

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

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