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Some Light Science Reading. The Constellations: Cetus

Friday, November 19th, 2010

As first appeared in the October 2010 edition of the Syracuse Astronomical Society newsletter The Astronomical Chronicle (PDF).

Constellation Map generated with Starry Night Pro 6.

There is a region of the Night Sky that is dominated by aquatic creatures. Alternately, if we consider empty space as its own kind of ocean, there are regions where the stars of the Aquatic Constellations appear to undulate at geologic time scales, making the current arrangement of stars effectively motionless to our eyes and those of many generations to come.

Within this Water Region are the Constellations (as listed at wikipedia) Aquarius, Capricornus, Cetus, Delphinus, Eridanus, Hydra, Pisces, and Piscis Austrinus. If we think in terms of seasonal change, this does seem like an oddity of planning. Who would place the Aquatic Constellations in the Night Sky during the late fall and winter, when the temperature in some parts of the Northern Hemisphere (such as at Darling Hill Observatory) might as well be that of interstellar space? Where are the polar bear and penguin Constellations?

Constellation Map generated with Starry Night Pro 6.

The answer to this has less to do with the apparent location of these Constellations in our Night Sky and more to do with the position of the Sun during our daytime sky roughly six months later (the Sun IN Pisces, for instance). When the Sun is in this region of the sky from our terrestrial perspective, the Northern Hemisphere is well into Spring, the time of the rainy season in our and ancient cultures. The image above shows the position of the Sun at noon on April 1, 2011. No joke. If our blue sky were to disappear, we’d have a few seconds to enjoy the daytime Constellations (before we passed out, were cooked by radiation, or froze to death, depending on where the atmosphere went. Fun factoid – Mercury, with no atmosphere to speak of, provides 24-hour Constellation observing!).

This brings us to Cetus, formerly known as a sea monster (indirect evidence for the lack of submarines in ancient Greece?), now increasingly considered to be a whale (perhaps equally terrifying to a small boat far from land in antiquity). Like some misidentified sea monster seen from a dry beach by a hydrophobic observer, Cetus provides a small amount of clear identification and several subtle treats for Earth-locked amateur astronomers that leave quite a bit to the imagination.

Constellation Map generated with Starry Night Pro 6.

One of the patient treats in Cetus is the variable multiple star Mira (Omicron Ceti). As our Observatory Director Ray Dague pointed out at our last Public Viewing session, this star takes its own 331.65 day journey from a 10.1 magnitude star to a 2.0 magnitude star. That is a phenomenal change! It is current at 6.5 magnitude and found in the neck of the beast (above).

M77 image by Hunter Wilson.

As for Messier Objects, those objects one can definitely say they saw on first pass with even moderately-sized binoculars, Cetus is accompanied by only M77, a distant (47 million light years away) barred spiral galaxy (at left, photo by Hunter Wilson). While one distant galaxy is anchored in this part of the sky, this small region is host to tens-of-thousands of invisible objects swimming around our Sun. Cetus is a border Constellation to the Zodiac, those 12 Constellations that mark the path of the Sun and planets from our observing post on Earth. By the way the borders are drawn, Cetus does play host very occasionally to planets and, notably, the objects of the Asteroid Belt. Cetus had the distinction of being the host to 4 Vesta (shown below, photo from the Hubble Space Telescope), the 2nd largest object identified in the Asteroid Belt, during its discovery on 29 March 1807 by Heinrich Wilhelm Olbers.

4 Vesta (Images taken 2007 May 14 and 16). From hubblesite.org.

And then there’s stuff we can only imagine seeing without the most powerful scopes in the known universe. Cetus is the host to JKCS 041 (shown below, also in the neck as marked in the opening image. Must be a hungry monster), the current holder of the title as most distant galaxy cluster yet discovered, residing at a boggling distance of 10.2 billion light years from us. Wikipedia hosts a short little movie about this distant cluster HERE.

JKCS 041 (22 Oct 2009) from NASA/CXC/INAF/S.Andreon et al Optical: DSS; ESO/VLT.

Clear skies, Damian

P.S. It has taken all my concentration to not refer to Cetus as a Whale of a Constellation.

Some Light Science Reading. The Constellations: Libra

Tuesday, May 18th, 2010

As first appeared in the May 2010 edition of the Syracuse Astronomical Society newsletter The Astronomical Chronicle (PDF).

Constellation Map generated with Starry Night Pro 6.

It is only fitting that, as we approach Summer and the unbelievable wealth of binocular and telescope objects that reside within the central region of the Milky Way, we spend at least one article on an otherwise mundane (to the amateur astronomer, anyway) Constellation. We endeavor this act of balance in the presentation of night sky viewing (and in the interest of accounting for all of the sky by the time these articles are done) by featuring Libra, The Scales.

The history of Libra in Western culture is one of science, religion, theft, imminent domain, here-say, and whatever existed as copyright in the Roman days (it is tough to make a Constellation associated with the Law interesting enough for prime time TV, as the only thing there is to murder is the presentation of any historical interpretation attributed to it). The reference to this collection of stars as a balance is reported to go as far back as the Sumerians (approximately 2000 B.C.), where this collection was known as “ZIBBA AN-NA”, or the “balance of heaven.” It is of particularly humorous irony this month that the Greeks were responsible for the disappearance of “the balance” from the night sky in favor of over-inflating the magnitude of the already important constellation Scorpius (for historical perspective, this article is being written as Greek economic infrastructure is falling apart faster than the Parthenon during the Siege of Athens in 1687 by Francesco Morosini, the Doge of Venice [as a good Greek, I shake my fist at the Gods in anger]).

The Romans saw fit to either return to the Sumerian tradition or simply declaw Scorpius, as Libra once again became a set of Scales. It is fate that the pinchers of an arthropod would be returned to the type of covering for reptiles. With the first publications of Libra-friendly star groupings and names upon the demotion of the now more diminutive Scorpius, one might even argue that the pen is mightier than the claws.

When not being visually accosted by rock n’ roll advertisements for lawyers behind cheap bookcase backdrops offering beaucoup bucks for your injury settlements, the legal profession often seems quite dull and arcane in its own right (sorry, Ray). Libra is equally subdued in its presentation, offering no Messier Objects within its official borders and no other really “interesting” things observable through binoculars or small telescopes. Perhaps the most interesting aspect about the constellation itself is its identification as the only inanimate object of the Zodiac, the ring of Constellations that encompass the ecliptic, or the apparent path of the Sun throughout the year.

That is not, however, to say that there isn’t anything worth its weight in hydrogen residing within the Libra boundaries. If we perform a considerable zooming in just above Zubeneschamali (phew! That translates to the “northern claw,” just as its counterpart Zubenelgenubi translates to the “southern claw.” These names would indicate that Arab astronomers opted to use both Greek and Roman sources despite the obvious conflict in the star groupings), we can see (with very good scopes) the star Gliese 581 (shown below), home of one of the most populated planetary systems yet discovered (although it is important to remember that this number is only of those planets we can detect, which means those with significant gravitational influence on their stellar anchor). This is marked “1” in the opening image. To date, there are four detected stars around Gliese 581 (note that the star name is always first, followed by a letter designation), including Gliese 581 b, a Neptune-sized object with a 5.4 day orbit, c, a rocky Earth-like planet within the Gliese 581 Habitable Zone 1.5 times wider and 5 times more dense than our own, d, a planet 1/2 as massive as Uranus and still within in the Habitable Zone, and e, a planet 1.6 times as massive as Earth and the smallest yet identified. the star Gliese 581 not only represents a feat of mathematical prowess on the part of Terran researchers, but is also of specific interest because of the number of planets within its Habitable Zone, the region within which conditions are believed to be similar to our own (specifically, liquid water on the surface). Some even refer to this as the “Goldilocks Zone,” where it’s not too cold and not too hot. One might say that this region is where a proper balance of hot and cold is reached…

Gliese 581

Of all of the asterisms (groups of stars that are not designated as Constellations but that still have specific meaning. For instance, the Big Dipper is an asterism within the Constellation Ursa Major) that have jumped out at me during my binocular viewing adventures, the one marked by the “2″ is perhaps the one that most stood out to my eyes. It is one of the most perfect isosceles triangles in the nighttime sky and is reasonably clear around it such that only this shape stands out in low-power optics. When it’s out, I always look for this small golden nugget residing within the Zubeneschamali-side of the scales, tipping the balance towards the arrival of the Summer constellations Scorpius and Sagittarius, the pair that mark the inside of our own galaxy and where a disproportionate number of Messier riches abound.

Some Light Science Reading. The Constellations: Coma Berenices

Tuesday, May 18th, 2010

As first appeared in the April 2010 edition of the Syracuse Astronomical Society newsletter The Astronomical Chronicle (PDF).

Constellation Map generated with Starry Night Pro 6.

I continue to groom the Eastern sky in this month’s Constellation presentation by spending some time conditioning you to appreciate the subtle shapeliness and glowing highlights just a short clip from last month’s subject, Canes Venatici (I will endeavor to refrain from additional dry hair humor in the rest of the article). Coma Berenices, or “Berenice’s Hair,” is an unusual constellation in many respects. It is one of the few constellations that owes its name (and history) to an actual person, is one of the constellations that was promoted from a lowly asterism, it marks the location of the North Galactic Pole, and, as one of the edge-sharing constellations with Virgo, Coma Berenices contains a plethora of Messier Objects (and is an excellent constellation to have memorized if binocular viewing is in your future and you just don’t wanna wait to find something). As has been a general theme with many of these past articles, even the most simple constellations have weaved into them a wealth of astronomical treasures.

“The lives of the priests were almost cut as short as Queen Berenice’s hair.” I have to assume this line has been told in one form or another over the course of the last few millennia as part of the discussion of this simple right angle. Queen Berenice II was the wife of King Ptolemy III Euergetes of Egypt, perhaps best known as the monarch under whom the great port city of Alexandria, home to such notable Greek mathematicians as Euclid and Pappus (you did know what I meant by a “right angle,” didn’t you?) rose to prominence. As history tells us, Ptolemy rode off to seek revenge for the death of his sister, Berenice promised the goddess Aphrodite her hair upon Ptolemy’s safe return, Aphrodite saw fit to collect on said offering, and Berenice offered her golden locks to Afro, er, pardon, Aphrodite’s temple. As if her bad hair day were not enough, the next morning found her offering gone from the temple. The court astronomer Conon of Samos offered the most logical explanation (much to the relief of the temple priests, who were close to getting a far-too-close shave of their own), one which was so convincing that it remains with us today. Aphrodite, well, washed that hair right away from those men, and sent it on its way… skyward. What we now know as Coma Berenices had, at one time (and likely for some amount of time after), been the furry end of the tail of Leo the Lion, Berenice’s close and equally blonde companion. It is believed that Come Berenices graduated from asterism (simply any collection of stars that are NOT official constellations) to constellation with the help of Tycho Brahe in his 1602 star catalogue (reinforced by Johann Bayer in his 1603 work, Uranometria).

The dwarf planet Makemake.

It is a testament to the changing times that I can mention the presence of a planetary neighbor tangled in Coma Berenices that I would not have known to mention when the new SAS newsletter began its membership cycle only two years ago. The dwarf planet Makemake (shown above from a Hubble image and provided to wikipedia by Mike Brown, its discoverer) is currently veryvery close to the south-most bright star, gamma-Com. While helping to provide a marker for one of the smallest catalogued objects in the Night Sky, Coma Berenices also marks an important location for our most important source of observables in the same Sky. The North Galactic Pole (position shown below), is the point 90 degrees above us with respect to the galactic plane (the discussion of the Galactic Coordinate System is far too, well, large to include here, so I refer you to its wikipedia entry HERE).

The North Galactic Pole

Coma Berenices hosts a single Messier Object that is not a galaxy, although, like hair, detail is based on proximity. M53 is a bino-visible (7.7 magnitude) globular cluster approximately 65,000 light years away. As is often the case, our terran view (especially in CNY) does not do this object the justice provided by our tax dollars in the form of Hubble images (shown below). Looking at the constellation image at the top of this article, you may notice a bit of a knot just to the right of Makemake. As it happens, the density of stars in this region of Coma Berenices is high enough that is does have a designation as the very open cluster Melotte 111 in the less well known “other-M” Melotte catalogue. We are far too close to it for the cluster to appear to us as something like the densely-packed Pleiades, but there may be a close-by planet to the Pleiades saying the same thing about the region around our gamma-Com!

M53

The rest of the Messier Objects in Coma Berenices are galaxies, with all but one of them bright (close-by) members of the Virgo Cluster, the gigantic collection of up-to 2000 galaxies discussed briefly in last month’s newsletter. Coma Berenices and its border with Virgo are regions that all Messier Marathoners cannot wait to have appear prominently in their early-morning March skies, as finding and checking-off these objects in your race-to-the-finish search as fast as two-in-one shampooing. The six Virgo members are (listed top-down) M85, M100, M98, M99, M88, and M91. You will note that M86, M84, M90, M89, M87, M58, M59, and M60 (phew!) are also in very close proximity in Virgo. Your problem is not finding smudge patches in your binoculars. You’re problem is finding out which one you’re looking at!

The lenticular (a morphological hybrid between elliptical and spiral galaxy shapes) galaxy M85 (NGC 4382) marks the northernmost edge of the Virgo cluster. Admittedly, the detail in the Hubble image is a bit lacking (shown below), one of the signs of an old elliptical galaxy where star formation is no longer ongoing in any significant amount). This galaxy lies 60 million light years away and is the 94th MOST distant Messier Object. With M85 centered in your Telrad, you’ll find M100 just at the edge of your outer ring.

M85

M100 (NGC 4321, shown at below-left from ESO) has a shape to it that all likely think of when they picture a galaxy in their mind’s eye. One of the most prominent members of the Virgo cluster, this “grand design spiral” galaxy is 55 million light years away and has been observed intensely enough for us to know that it hosts the satellite galaxy NGC 4323. As galaxies go, M100 is jumpin’ with supernovae, with five catalogued since 1901. Centering your Telrad on M100, M99 approaches your outer ring by about the amount that M98 and M88 sits beyond it.

M100

We see the spiral galaxy M98 (NGC 4192, shown below, from Astrofotografia) almost edge-on, making for a view similar to, but less interesting that, the Andromeda Galaxy (M31). If you’re keeping excellent track of your Doppler shifting, you’ll note that M98 is racing towards us at 125 km/sec which, at 60 million light years away, gives us plenty of time to hit the salon before its arrival.

The image of the pinwheel-looking (a name that already has the galaxy M33 associated with it) M99 (below), was taken by amateur astronomer Hunter Wilson and is currently the choice image at wikipedia for this galaxy (no small feat considering the telescope competition both on the ground AND in orbit). The slight unwinding (well, slight to our eyes, but tens of thousands of light years fit into that gap) of the right-most arm is attributed to VIRGOHI21, a region of hydrogen gas and a massive amount of presumed dark matter.

M99

The spiral galaxy M88 (NGC 4501, shown below and also by Hunter Wilson) is racing towards the center of the Virgo cluster (in the direction of M87). This galaxy is noteworthy for its very tight and very regular spiraling that falls smoothly all the way to the galaxy core, home of a supermassive black hole 80 million times the mass of the Sun.

M88

The last Messier member of the Virgo cluster in Coma Berenices is M91 (NGC 4548, shown below). Messier (in 1781) and Herschel (in 1784) both lay claim to its discovery despite the gap in timing. The linked picture for this image is as noteworthy for the soft blending of nebulosity and starry regions as for the multitude of small galaxies also contained in the field of view. Well worth a look.

M91

Finally, the outlier Messier galaxy in this region is M64 (NGC 4826, shown below), known to amateur astronomers as the Black Eye Galaxy. This view is obvious even in our telescopes! Not only is the galaxy interesting for the dark band pointed towards us, but it has become doubly-interesting recently with the discovery that the black band is spinning in the opposite direction of the rest of the galaxy, with the current hypothesis being that the black band is the remains of a companion galaxy that may have collided with the central galaxy one billion years ago. when you next see it, think of the astronomer Conon and the priests he saved from a similar fate.

M64

Some Light Science Reading. The Constellations: Sagittarius

Sunday, July 26th, 2009

As first appeared in the July 2009 edition of the Syracuse Astronomical Society newsletter The Astronomical Chronicle (PDF).

Image generated with Starry Night Pro 6, www.starrynight.com.

The Constellations, for all of their mythological, mystical, and ceremonial significance throughout human history, are also the bases for much of the scientific discovery (the Zodiac was a calendar long before it was ever used to identify the other kind of dates, and the backdrop of the unchanging Heavens served as the guide against which the motions of the planets were first tracked) that fueled our understanding of the universe before Edwin Hubble first exposed its true vastness by identifying the “Andromeda Nebula” as, in fact, a galaxy far outside of the Milky Way. The constellations have also served in a far more pragmatic capacity throughout human history as seasonal sign posts, simply marking times and locations for those on land and sea. Perhaps the most famous example of this in American History is the use of the Big Dipper as the marker by freed slaves traveling North along the Underground Railroad. The song “Follow the Drinkin’ Gourd” is not simply a series of verses, but is instead a set of instructions, with the “Drinkin’ Gourd” being the Big Dipper, the most easily recognizable asterism in the Northern Hemisphere (amateur astronomer or not) and pointer (by drawing an arrow from Merak to Dubhe) to the North Star Polaris, itself the most famous star of the Little Dipper (also known as Ursa Minor), an otherwise somewhat unimpressive constellation (certainly not as prominent in the North as the Big Dipper or the Cassiopeia “W” and, therefore, not as useful a sign post).

The Little Dipper is not the most prominent constellation in the Night Sky, but it serves as an important terrestrial marker because it includes Polaris among its member stars. Just as the Big Dipper is a prominent asterism that directs you to the Little Dipper, the Summer constellation Scorpius (which has been recognized specifically as a scorpion by many cultures for several millennia) can draw you to a slightly less prominent constellation to its West that is a sign post to a far more impressive marker than Polaris.

Sagittarius is an astronomy instructor’s dream constellation, as it wraps up a number of interesting topics of discussion in one easy-to-find location. To begin, the Centaur, a half-human/half-horse hybrid, is the perfect bridge between the fantastical world of mythology in all of its seeming ridiculousness and, well, the shining example of what might even be ridiculously possible as scientists learn more about DNA and biological engineering (as of this past May, we now can make monkeys that glow in the dark. That’s right, in the dark).

Second, Sagittarius provides its viewer another shining example of the difference between a constellation and an asterism. A constellation is, simply, a specific grouping of stars that everyone has agreed are, in fact, assigned to that particular constellation. This circular definition was finally laid flat by the International Astronomical Union in its defining of Constellation Boundaries, solidifying star groupings that go as far back as antiquity and as far forward as 1763 (the exploration of the Southern Hemisphere was not limited to the land and the sea). An asterism is, simply, a convenient grouping of stars that are NOT one of the 88 Official Constellations, with some asterisms being only fragments of a full Constellation (such as the Big Dipper, the most famous asterism in the Constellation Ursa Major) and some asterisms composed of parts of multiple Constellations (such as the Summer Triangle, composed of the stars Deneb (Cygnus), Altair (Aquila), and Vega (Lyra). At our latitude (Syracuse and Tully), we cannot even see the entire Constellation of Sagittarius, but have an excellent view during the Summer of one of the most modern of conveniences in the form of a Tea Pot (see below). We may seem a little ridiculous pointing out the tea pot, short and stout, with its handle (on the left or to the West) and its spout (on the right or to the East) at Darling Hill on a dark night, but you will not forget this asterism after it jumps out at you the first time. An important thing to remember is that any grouping of stars in the sky that helps YOU find what you are looking for is as significant an asterism as one you might find in any book. If an otherwise unlabeled grouping jumps out at you that helps you find your place in the Night Sky, put those informal naming rights to good use.

Image generated with Starry Night Pro 6, www.starrynight.com.

Third, the billowing steam from the spout of this tea pot marks a most important location to all 100 billion or more stars in our galaxy. The small darkened oval in the picture above marks the exact location of the center of the Milky Way galaxy (the tiny, fuzzy spec at its middle), meaning we are looking into the most dense region of the galaxy when we set our gazes at this region. Unfortunately, the city lights from Cortland wash the density of the Milky Way band at our South when we observe in Tully, although the full band of the Milky Way is prominent above us during the Summer.

Images from ircamera.as.arizona.edu.

Fourth, because we are looking into the heart of the Milky Way when we see the spout of the tea pot (as the image at right tries to show), we are looking into the densest region of stars we can see from Earth. As a result, this tea pot marks the location of a variety of Messier Objects and fainter nebulae far more numerous than even the largest variety pack the other Celestial Seasonings (pardon the tea pun) has to offer. The Trifid Nebula (M20), Lagoon Nebula (M8), Sagittarius Cluster (M22), Omega Nebula (M17), Black Swan Nebula (M18), M25, M23, M55, M54, M70, M28, M21, and M75 all reside within the Sagittarius boundary, while M6, M7, M16, and a host of other deep sky objects surround its borders in neighboring Scorpius, Ophiuchus, and Serpens Cauda.

When we observe during the Summer, I often recommend to new visitors with binoculars to simply point to the South, aim for the tea pot, and slowly scan. If your binoculars or telescope are anywhere near focused, you are guaranteed to find something within your field of view.

Mildly thirsty just thinking about it,
Damian

www.syracuse-astro.org
en.wikipedia.org/wiki/Constellation
en.wikipedia.org/wiki/Zodiac
www.match.com
en.wikipedia.org/wiki/Planets
en.wikipedia.org/wiki/Edwin_Hubble
en.wikipedia.org/wiki/Andromeda_Galaxy
en.wikipedia.org/wiki/Milky_Way
en.wikipedia.org/wiki/American_History
en.wikipedia.org/wiki/Big_Dipper
en.wikipedia.org/wiki/Underground_Railroad
en.wikipedia.org/wiki/Follow_the_Drinkin%27_Gourd
en.wikipedia.org/wiki/Northern_Hemisphere
en.wikipedia.org/wiki/Beta_Ursae_Majoris
en.wikipedia.org/wiki/Dubhe
en.wikipedia.org/wiki/Polaris
en.wikipedia.org/wiki/Little_Dipper
en.wikipedia.org/wiki/Cassiopeia_(constellation)
en.wikipedia.org/wiki/Scorpius
en.wikipedia.org/wiki/Sagittarius_(constellation)
en.wikipedia.org/wiki/Centaur
www.huffingtonpost.com/2009/05/27/glowing-baby-monkeys-marm_n_208296.html
www.engr.wisc.edu/wiscengr/feb02/monkey.shtml
www.examiner.com/x-9343-Denver-Health-Examiner~y2009m5d29-Monkeys-that-glow-in-the-dark
www.iau.org
en.wikipedia.org/wiki/List_of_constellations
en.wikipedia.org/wiki/Southern_Hemisphere
en.wikipedia.org/wiki/Asterism_(astronomy)
en.wikipedia.org/wiki/Summer_Triangle
en.wikipedia.org/wiki/Deneb
en.wikipedia.org/wiki/Altair
en.wikipedia.org/wiki/Vega
en.wikipedia.org/wiki/Sagittarius_(constellation)
en.wikipedia.org/wiki/Messier_20
en.wikipedia.org/wiki/Messier_8
en.wikipedia.org/wiki/Messier_22
en.wikipedia.org/wiki/Messier_17
en.wikipedia.org/wiki/Messier_18
en.wikipedia.org/wiki/Messier_25
en.wikipedia.org/wiki/Messier_23
en.wikipedia.org/wiki/Messier_55
en.wikipedia.org/wiki/Messier_54
en.wikipedia.org/wiki/Messier_70
en.wikipedia.org/wiki/Messier_28
en.wikipedia.org/wiki/Messier_21
en.wikipedia.org/wiki/Messier_75
en.wikipedia.org/wiki/Messier_6
en.wikipedia.org/wiki/Messier_7
en.wikipedia.org/wiki/Messier_16
en.wikipedia.org/wiki/Scorpius
en.wikipedia.org/wiki/Ophiuchus
en.wikipedia.org/wiki/Serpens_Cauda

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