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Sirius is the brightest star as seen from Earth, apart from the Sun. Credit: Mellostorm.{{free media}}

The first red source in Canis Major is unknown.

This is a lesson in map reading, coordinate matching, and researching. It is also a research project in the history of red astronomy looking for the first astronomical red source discovered in the constellation of Canis Major.

Nearly all the background you need to participate and learn by doing you've probably already been introduced to at a secondary level.

Some of the material and information is at the college or university level, and as you progress in finding red sources, you'll run into concepts and experimental tests that are actual research.

To succeed in finding a red source in Canis Major is the first step.

Next, you'll need to determine the time stamp of its discovery and compare it with any that have already been found. Over the history of red astronomy a number of sources have been found, many as point sources in the night sky. These points are located on the celestial sphere using coordinate systems. Familiarity with these coordinate systems is not a prerequisite. Here the challenge is geometrical, astrophysical, and historical.

Control groups

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A control group for this experiment may be a red source observed by ancient hominins in their version of the constellation Canis Major.

Reds

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Main resource: Radiation astronomy/Reds
The Red Rectangle is a proto-planetary nebula. Credit: JPL/NASA.{{free media}}

Here at left is the Hubble Space Telescope Advanced Camera for Surveys (ACS) image of the Red Rectangle, a proto-planetary nebula. Broadband red light is shown in red.

"Most of the sources are resolved in [Hubble Space Telescope] HST F814W imaging so they are certainly galaxies and not M stars."[1]

First sources

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Main resource: First astronomical sources

The "earliest known astronomy anywhere in the world [is] that of the Australian Aborigines, whose culture has existed for some 40,000 years".[2]

"The Aranda tribes of Central Australia, for example, distinguish red stars from white, blue and yellow stars."[2]

Around 150 AD, the Hellenistic astronomer Claudius Ptolemy described Sirius as reddish, along with five other stars, Betelgeuse, Antares, Aldebaran, Arcturus and Pollux, all of which are clearly of orange or red hue.[3] The discrepancy was first noted by amateur astronomer Thomas Barker, who prepared a paper and spoke at a meeting of the Royal Society in London in 1760.[4] The existence of other stars changing in brightness gave credence to the idea that some may change in colour too; Sir John Herschel noted this in 1839, possibly influenced by witnessing Eta Carinae two years earlier.[3] Thomas Jefferson Jackson See resurrected discussion on red Sirius with the publication of several papers in 1892, and a final summary in 1926.[3] He cited not only Ptolemy but also the poet Aratus, the orator Cicero, and general Germanicus as colouring the star red, though acknowledging that none of the latter three authors were astronomers, the last two merely translating Aratus' poem Phaenomena.[3] [Seneca the Younger] Seneca, too, had described Sirius as being of a deeper red colour than Mars.[5] However, not all ancient observers saw Sirius as red. The 1st century AD poet Marcus Manilius described it as "sea-blue", as did the 4th century Avienus.[3] It is the standard star for the color white in ancient China, and multiple records from the 2nd century BC up to the 7th century AD all describe Sirius as white in hue.[6][7]

In 1985, German astronomers Wolfhard Schlosser and Werner Bergmann published an account of an 8th century Lombardic manuscript, which contains De cursu stellarum ratio by St. Gregory of Tours. The Latin text taught readers how to determine the times of nighttime prayers from positions of the stars, and Sirius is described within as rubeola — "reddish". The authors proposed this was further evidence Sirius B had been a red giant at the time.[8]

Backgrounds

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Main resource: Radiation astronomy/Backgrounds

To introduce yourself to some aspects of the challenge may I suggest reading the highlighted links mentioned above, and if you're curious, those listed under the section "See also" below.

Red rays are a form of radiation that is currently part of the electromagnetic radiation intersecting the Earth. More information about radiation is in radiation astronomy and red astronomy.

Constellations

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This is an image of the International Astronomical Union (IAU) sky map of the constellation Canis Major. Credit: IAU and Roger Sinnott & Rick Fienberg, Sky & Telescope magazine.{{free media}}

The Wikipedia article about the constellation Canis Major contains a high school level description. The figure at right shows the sky map of Canis Major. Around the edges of the map are coordinates related to longitude and latitude, but with the Earth rotating on its axis every 24 hours the celestial coordinates must remain fixed. How has this been accomplished?

Also, in the Wikipedia article is a list of stars in Canis Major. What's the difference between a star and an astronomical red source?

From the Wikipedia article on the Zodiac, is Canis Major a zodiacal constellation?

Canis Major is one of the 88 modern constellations, and was included in the 2nd-century astronomer Ptolemy's 48 constellations. Canis Major is a constellation in the southern hemisphere's summer (or northern hemisphere's winter) sky. The three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is 'CMa'.[9] The official constellation boundaries, as set by Eugène Delporte in 1930, are defined by a polygon of 4 sides. In the equatorial coordinate system, the right ascension coordinates of these borders lie between 06h 12.5m and 07h 27.5m, while the declination coordinates are between -11.03° and −33.25°.[10] Covering 380 square degrees, it ranks 43rd of the 88 constellations in size.

Star classification by color

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Class Temperature[11]
K 		Conventional color Apparent color[12][13][14] Mass[11]
(solar masses, Mʘ) 		Radius[11]
(solar radii, Rʘ) 		Luminosity[11]
(bolometric, Lʘ) 		Hydrogen
lines 		Fraction of all
main sequence stars[15]
O ≥ 33,000 K blue blue ≥ 16 ≥ 6.6 ≥ 30,000 Weak ~0.00003%
B 10,000–33,000 K blue to blue white blue white 2.1–16 1.8–6.6 25–30,000 Medium 0.13%
A 7,500–10,000 K white white to blue white 1.4–2.1 1.4–1.8 5–25 Strong 0.6%
F 6,000–7,500 K yellowish white white 1.04–1.4 1.15–1.4 1.5–5 Medium 3%
G 5,200–6,000 K yellow yellowish white 0.8–1.04 0.96–1.15 0.6–1.5 Weak 7.6%
K 3,700–5,200 K orange yellow orange 0.45–0.8 0.7–0.96 0.08–0.6 Very weak 12.1%
M ≤ 3,700 K red orange red ≤ 0.45 ≤ 0.7 ≤ 0.08 Very weak 76.45%.

Testing a source

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There are many web sites that may have a red source listed for the constellation Canis Major.

Wikipedia sources

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A. Constellation article

Under "Notable features" in the Wikipedia article on the constellation Canis Major is the list of stars in Canis Major. Click on this link. In the table of this Wikipedia article is α CMa. To the right are coordinates:

  1. [Right ascension] (RA): 05h 45m 08.9173s and
  2. [Declination] (Dec): -16° 42' 58.017".

Find these coordinates on the Canis Major map at the right. Is alpha Canis Major really inside the boundaries of the constellation?

To evaluate the star as a red source, skip ahead to the section "Red source".

B. Wikipedia search

Another way to look for red sources in the constellation is to perform a search on Wikipedia. Try ""Canis Major" red" without the outside quotes. This yields 61 possible astronomical red source candidates.

To evaluate a red source, skip ahead to section "Red source".

SIMBAD sources

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Another way to find possible red sources in Canis Major is to use search queries on SIMBAD.

Click on the SIMBAD link under "External links" below, then click on "Criteria query" or "by criteria".

In the tan box, type in "region(05 45 08.9173 -16 42 58.017, 10m)", without the quotes. This tells the SIMBAD computer you are interested in a circular region of the celestial sphere centered on the coordinates for alpha Canis Majoris, with a radius of 10 arcminutes (m).

Notice on the page over at the right from the tan colored box: "Return". The default is "object count". Click on "submit query". In a few moments a result something like "Number of objects: 9" should appear. Click "Back" to see the tan box again.

To see if you have found at least one object, change "Return" to "display" by clicking on the circle to its left, then "submit query".

SIMBAD should display a list of objects. Read through the resource red astronomy for clues that may indicate whether a particular spectral type (Sp type) is a red source. If none of the objects listed seems to be described as a red source, try going "Back" and increasing the arcminutes from "10m" to "20m", and repeat until a red source is found.

Once you believe you have discovered a red source, proceed to the section "Red source".

Red source

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There are several ways to evaluate a red source for the constellation Canis Major.

Stellar classification

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Stellar classification places the range of effective surface temperatures for the class K stars as 3,700 - 5,200 K.[11]

Typical characteristics
Stellar
Class 		Standard
star
* Not a standard star. 		Radius
(Rʘ) 		Luminosity
(Lʘ) 		Teff
(K) 		Linear
approximation 		Planckian radiator
peak wavelength
(nm)
K0V 54 Psc --- --- 5,197 5,200
K0IV Delta Eri --- --- 5,024
K0III Epsilon Cyg --- --- 4,783
K1V Gliese 833* 81% --- 5,038 5,033
K1V HD 92945* 77% 38% 5,000 5,033
K1V HD 97658* 70% 30% 5,119 5,033
K2V Epsilon Eridani 74% 34% 5,084 ± 5.9 4,867
K2III Alpha Ari 1490% 91% 4,552
K2III Tau Gem 2700% 22400% 4,350
K3V HD 16160 --- --- 4,910 4,700
K3V HD 215497* 101% 39% 5,113 4,700
K3V HR 1614* 78% --- 5,945 4,700
K4III 17 Mon --- --- 4,096
K4III Beta Cnc --- --- 3,923
K4V Gliese 570* 74% 22% 4,597 4,533
K5V 61 Cygni A 67% 15% 4,526 ± 66 4,367
K5III Alpha Tau 4420% 51800% 3,813
K6 V1094 Scorpii 138% 56% 4,256 4,200
K7V 61 Cygni B 60% 8.5% 4,077 ± 59 4,033
K8V GJ 9081* --- --- --- 3,867
K9V GJ 1016* --- --- --- 3,700

Some of the effective temperatures for the K standard stars are fairly recent.[16]

Typical characteristics[17]
Stellar
Class 		Mass
(Mʘ) 		Radius
(Rʘ) 		Luminosity
(Lʘ) 		Teff
(K) 		Planckian radiator
peak wavelength
(nm)
M0V 60% 62% 7.2% 3,800 789
M1V 49% 49% 3.5% 3,600 833
M2V 44% 44% 2.3% 3,400 882
M3V 36% 39% 1.5% 3,250 922
M4V 20% 26% 0.55% 3,100
M5V 14% 20% 0.22% 2,800
M6V 10% 15% 0.09% 2,600
M7V 9% 12% 0.05% 2,500
M8V 8% 11% 0.03% 2,400
M9V 7.5% 8% 0.015% 2,300

The Planckian radiator peak wavelength for any effective surface temperature in K may be found using your handheld calculator with the formula:

y=(1.48833/(0.0000495*6060))*exp(1.48833/(0.0000495*6060))/(exp(1.48833/(0.0000495*6060))-1)-5.

Depending on the internal software, ask it to print or display y. Iteratively enter different temperatures (e.g. 6060 in the equation) and wavelengths (e.g. 495 nm as 0.0000495 in the equation) to see how close to zero you are.

For the temperature, wavelength pair (6060 K,495 nm), the value is -3.419065E-03. This is close in the third digit.

The spectral type K stars have their peak wavelength in the red band from approximately K3V through K9V. Why would they appear orange to us?

The temperature, wavelength pair (3800 K,690 nm) gives an equation of

y=(1.48833/(0.0000690*3800))*exp(1.48833/(0.0000690*3800))/(exp(1.48833/(0.0000690*3800))-1)-5, with a value of 0.695831, which is not as close, and suggests an error in the first digit.

When the temperature is higher than the minimum for a specific wavelength, the value of the equation is negative. When the wavelength is shorter than the minimum for a specific temperature, the value of the equation is positive.

As the Planckian radiator peak wavelength is in the infrared instead of the red, why are these M-class main sequence stars called red dwarfs rather than infrared dwarfs?

Wikipedia source

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Click on the link to the Wikipedia article. After you've enjoyed reading about the source, use the 'find' command of your browser to see if this Wikipedia page mentions anything about "red" or "red rays". Does the article mention whether or not the source is a red source?

What is the current time stamp for the Wikipedia article on the source? [Hint]: look for something like "This page was last modified on 12 January 2012 at 06:47." very near the bottom of the page. For now this is an adequate time stamp.

From reading the Wikipedia article on the source, if you believe the text demonstrates that the source is not a red source in Canis Major edit the "Non-red source in Canis Major" section near the bottom of the page with an entry similar to "# Alpha Canis Majoris 12 January 2012 at 06:47 Wikipedia article "Alpha Canis Majoris".", without the outer quotes, and finish the entry with four "~"s without the quotes after the period. The date included with your designation or username is a time stamp for the entry. The last portion of the entry is the source of your information.

On the other hand, if there are one or more sentences in the article that you believe demonstrates that the source is a red source in Canis Major edit the section below "Red source in Canis Major" with a similar entry.

Go to the section entitle, "Challenging an entry".

SIMBAD source

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To check any source (even one from Wikipedia) on SIMBAD, click of the "External link" to the "SIMBAD Astronomical Database".

At the lower right side of the SIMBAD Astronomical Database page is a "Basic search" box. There are several ways to try your target:

  1. source name: without the quotes or
  2. source coordinates: without the quotes, for example, "05 45 08.9173 -16 42 58.017".

If you are looking at a SIMBAD generated table which lists possible targets, click on one.

On its SIMBAD page move over to the right side until you see an Aladin visual photograph of the object. Is it a red source?

Even if the source does not look red, look down the left hand side of the page for "Spectral type:". From your reading of red astronomy, do you believe the source is a red source, or not? Noting that SIMBAD does, or does not consider the source to be a red source is important, so skip down to the "SIMBAD time stamp" section.

If you have already found a red source (or a table of them) using SIMBAD, click on the blue link identifier for the first.

SIMBAD time stamp

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Peruse the SIMBAD page for a time stamp or date of last revision. [Hint: it may look something like "2012.01.09CET20:10:02" and be in the upper right.]

If the entry at SIMBAD convinces you that the source is not a red source, edit the "Non-red source in Canis Major" section near the bottom of this page and type in an entry similar to "# Source Name 2012.01.09CET20:10:02 SIMBAD article "SIMBAD source name".", without the first set of quotes, followed by four ~s.

If your SIMBAD analysis convinces you that you have found a red source in Canis Major (did you check the coordinates vs. the map of Canis Major?), make an entry something like the ones in the section "Red source in Canis Major".

Challenging an entry

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Any entry in either the section "Red source in Canis Major" or "Non-red source in Canis Major" can be challenged. The time stamp may be challenged to see if there is an earlier one. The source may be challenged by an earlier source.

Wikipedia challenge

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Is Wikipedia a 'primary source', or does the Wikipedia article cite a source?

Even though Wikipedia has an article on the source, is it a good place to stop in testing whether the source has been detected as an astronomical red source?

If the Wikipedia article cites a primary source, skip down to the section on "Primary sources".

SIMBAD challenge

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Is SIMBAD a 'primary source'?

SIMBAD is an astronomical database provided by the Centre de Données astronomiques de Strasbourg. It is an authoritative source, but they do occasionally make a mistake.

If you find a red source within the constellation on SIMBAD, the next step is to find the earliest time stamp of discovery.

Primary sources

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Primary sources may be searched for possible additional information perhaps not yet evaluated by SIMBAD or not presented in a Wikipedia article about a source.

Wikipedia test source

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For a Wikipedia article that cites a primary source, scroll down to the reference and open the reference. Read through the article looking for where the source mentioned in the Wikipedia article occurs. Some primary source authors may use source designations that are not mentioned in the Wikipedia article. To look for other designations, click on the link to SIMBAD in the "External links" on this page, enter the source name from the Wikipedia article, and see if other names are mentioned in the article.

When none of the names are mentioned, click on the link for "Google Advanced Search" in the list of "External links", enter the source name or designation(s) such as "Gliese 866", with "red" to see if the source has a reference indicating it is a red source. And, look for the earliest one. Compose an entry using the primary source.

SIMBAD test source

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Further down the SIMBAD page is a list of "Identifiers". Click on the blue bold portion.

On the page that appears, there should be a primary source listed after Ref:. Click on the blue link with the oldest year. This yields an earlier time stamp and entry citation like the current one in the section "Red source in Canis Major". If you find another source or an earlier time stamp, compose a similar entry and edit the section. Additional information to add into the reference can be found by clicking on "ADS services" from the SIMBAD page.

Changing an entry

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From your analysis of the source so far, is it a red source?

If you have found an earlier time stamp for the source than the one listed in the section below "Non-red source in Canis Major" and the answer to the above question is "no", you can edit the section with your result. Or, you can leave the entries as is and try another star or object.

If you have found an earlier time stamp for the source than the one listed in the section below "Red source in Canis Major", edit the section with your result. Or, if you found another red source with a comparable or earlier time stamp, edit the section with your result.

Red sources in Canis Major

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  1. Sirius: around 150 AD, the Greek astronomer of the Roman period Claudius Ptolemy described Sirius as reddish. This page was last modified on 31 July 2012 at 04:49. --Marshallsumter (talk) 19:59, 15 August 2012 (UTC)

Non-red sources in Canis Major

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  1. Sirius: or alpha Canis Majoris A, is a white main sequence star of spectral type A1V. This page was last modified on 31 July 2012 at 04:49. --Marshallsumter (talk) 19:55, 15 August 2012 (UTC)

Oldest source

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Around 150 AD, the Greek astronomer of the Roman period Claudius Ptolemy described Sirius as reddish.

Hypotheses

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Main resource: Hypotheses
  1. The first red source in Canis Major was probably observed around 42,000 b2k.

See also

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References

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  1. ↑ Michael C. Liu; Arjun Dey; James R. Graham; Charles C. Steidel; Kurt Adelberger (1999). Andrew J. Bunker. ed. Extremely Red Galaxies in the Field of QSO 1213-0017: A Galaxy Concentration at z = 1.31, In: The Hy-Redshift Universe: Galaxy Formation and Evolution at High Redshift. 193. Berkeley, California USA: American Society of Physics. pp. 344-7. ISBN 1-58381-019-6. Bibcode: 1999ASPC..193..344L. http://adsabs.harvard.edu/full/1999ASPC..193..344L. Retrieved 2013-07-30. 
  2. ↑ 2.0 2.1 R Haynes (June 27, 1996). Raymond Haynes. ed. Explorers of the southern sky: a history of Australian astronomy. Cambridge, England, UK: Cambridge University Press. pp. 527. ISBN 0521365759. http://books.google.com/books?id=XoeiJxMmXZ8C&lr=&source=gbs_navlinks_s. Retrieved 2013-08-02. 
  3. ↑ 3.0 3.1 3.2 3.3 3.4 J.B. Holberg (2007). Sirius: Brightest Diamond in the Night Sky. Chichester, UK: Praxis Publishing. ISBN 0-387-48941-X. 
  4. ↑ R. C. Ceragioli (1995). "The Debate Concerning 'Red' Sirius". Journal for the History of Astronomy 26 (3): 187–226. 
  5. ↑ Whittet, D. C. B. (1999). "A physical interpretation of the 'red Sirius' anomaly". Monthly Notices of the Royal Astronomical Society 310 (2): 355–359. doi:10.1046/j.1365-8711.1999.02975.x. 
  6. ↑ 江晓原 (1992). "中国古籍中天狼星颜色之记载". Ť文学报 33 (4). 
  7. ↑ Jiang, Xiao-Yuan (April 1993). "The colour of Sirius as recorded in ancient Chinese texts". Chinese Astronomy and Astrophysics 17 (2): 223–8. doi:10.1016/0275-1062(93)90073-X. 
  8. ↑ Schlosser, W.; Bergmann, W. (November 1985). "An early-medieval account on the red colour of Sirius and its astrophysical implications". Nature 318 (318): 45–6. doi:10.1038/318045a0. 
  9. ↑ Russell, Henry Norris (1922). "The New International Symbols for the Constellations". Popular Astronomy 30: 469–71. 
  10. ↑ "Canis Major, Constellation Boundary". The Constellations (International Astronomical Union). http://www.iau.org/public/constellations/#cma. Retrieved 15 November 2012. 
  11. ↑ 11.0 11.1 11.2 11.3 11.4 Tables VII, VIII, Empirical bolometric corrections for the main-sequence, G. M. H. J. Habets and J. R. W. Heinze, Astronomy and Astrophysics Supplement Series 46 (November 1981), pp. 193–237, bibcode=1981A&AS...46..193H. Luminosities are derived from Mbol figures, using Mbol(ʘ)=4.75.
  12. ↑ The Guinness book of astronomy facts & feats, Patrick Moore, 1992, 0-900424-76-1
  13. ↑ The Colour of Stars. Australia Telescope Outreach and Education. 2004-12-21. http://outreach.atnf.csiro.au/education/senior/astrophysics/photometry_colour.html. Retrieved 2007-09-26.  — Explains the reason for the difference in color perception.
  14. ↑ What color are the stars?, Mitchell Charity. Accessed online March 19, 2008.
  15. ↑ Glenn LeDrew (February 2001). "The Real Starry Sky". Journal of the Royal Astronomical Society of Canada 95 (1 (whole No. 686, February 2001), pp. 32–33. Note: Table 2 has an error and so this article will use 824 as the assumed correct total of main-sequence stars). http://adsabs.harvard.edu/abs/2001JRASC..95...32L. 
  16. ↑ S. Catalano; K. Biazzo; A. Frasca; E. Marilli (November 2002). "Measuring starspot temperature from line depth ratios". Astronomy & Astrophysics 394 (3): 1009-21. doi:10.1051/0004-6361:20021223. http://www.aanda.org/articles/aa/full/2002/42/aa2543/node1.html. Retrieved 2012-08-15. 
  17. ↑ Lisa Kaltenegger, Wesley A. Traub (June 2009). "Transits of Earth-like Planets". The Astrophysical Journal 698 (1): 519-527. doi:10.1088/0004-637X/698/1/519. 
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{{Radiation astronomy resources}}{{Reasoning resources}}

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