Radiation astronomy/First ultraviolet source in Sagittarius

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These two photographs were made by combining data from NASA's Galaxy Evolution Explorer spacecraft and the Cerro Tololo Inter-American Observatory in Chile. Credit: NASA/JPL-Caltech/JHU.

The first ultraviolet source in Sagittarius is unknown.

The field of ultraviolet astronomy is the result of observations and theories about ultraviolet sources detected in the sky above.

The first astronomical ultraviolet source discovered may have been the Sun.

But, ultraviolet waves from the Sun are intermingled with other radiation so that the Sun may appear as other than a primary source for ultraviolet waves.

The early use of sounding rockets and balloons to carry ultraviolet detectors high enough may have detected ultraviolet waves from the Sun as early as the 1940s.

This is a lesson in map reading, coordinate matching, and searching. It is also a project in the history of ultraviolet astronomy looking for the first astronomical ultraviolet source discovered in the constellation of Sagittarius.

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

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

First step[edit]

Main sources: Step/First and First step

The first step is to succeed in finding a ultraviolet source in Sagittarius.

Next, you'll need to determine the time stamp of its discovery and compare it with any that have already been discovered.

Over the history of ultraviolet 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. The coordinates are usually supplied by the ultraviolet source observers.

Astronomical sources[edit]

Def. a natural source usually of radiation in the sky especially at night is called an astronomical source.

A source of astronomical information on older detections of ultraviolet sources is included in the Science section of the lecture/article ultraviolet astronomy.

Traveling ultraviolet sources[edit]

This picture was taken in ultraviolet (extremely blue) light. Credit: EIT, SOHO, ESA, and NASA.

Many ultraviolet sources do not remain in a constellation for lengthy periods. Some of these are the Sun and sources apparently in orbit around the Sun. The Sun travels through the 13 constellations along the ecliptic (the plane of the Earth's orbit around the Sun): the 12 of the Zodiac and the constellation Ophiuchus. These are described in source astronomy. Sagittarius is one of the constellations of the Zodiac.

Backgrounds[edit]

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.

Ultraviolet waves are a form of radiation that is currently part of electromagnetic radiation intersecting the Earth. More information about radiation is in radiation astronomy.

Constellations[edit]

This is an image of the International Astronomical Union (IAU) sky map of the constellation Sagittarius. Credit: IAU and Sky & Telescope magazine (Roger Sinnott & Rick Fienberg).
Sagittarius is depicted in Urania's Mirror, a set of constellation cards published in London c.1825. Credit: Sidney Hall, Richard Rouse Bloxam, Adam Cuerden.

The Wikipedia article about the constellation Sagittarius contains a high school level description. The figure at top right shows the sky map of Sagittarius. 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 relative to the background light sources in the sky.

"Sagittarius [...] is one of the 48 constellations listed by the 2nd-century astronomer Ptolemy".[1]

"The Babylonians identified Sagittarius as the god Nergal, a strange centaur-like creature firing an arrow from a bow.[2] It is generally depicted with wings, with two heads, one panther head and one human head, as well as a scorpion's stinger raised above its more conventional horse's tail. The Sumerian name Pabilsag is composed of two elements – Pabil, meaning 'elder paternal kinsman' and Sag, meaning 'chief, head'. The name may thus be translated as the 'Forefather' or 'Chief Ancestor'.[3] The figure is reminiscent of modern depictions of Sagittarius."[1]

"In Greek mythology, Sagittarius is usually identified as a centaur: half human, half horse. However, perhaps due to the Greek's adoption of the Sumerian constellation, some confusion surrounds the identity of the archer.[4] Some identify Sagittarius as the centaur Chiron, the son of Philyra and Saturn and tutor to Jason, who was said to have changed himself into a horse to escape his jealous wife, Rhea. However, Chiron is in fact represented by the constellation Centaurus, the other heavenly centaur.[4] An alternative tradition is that Chiron merely invented the constellation Sagittarius to help in guiding the Argonauts in their quest for the Golden Fleece.[5]"[1]

"A competing mythological tradition, as espoused by Eratosthenes, identified the Archer not as a centaur but as the satyr Crotus, son of Pan, who Greeks credited with the invention of archery.[4][6] According to myth, Crotus often went hunting on horseback and lived among the Muses, who requested that Zeus place him in the sky, where he is seen demonstrating archery.[4]"[1]

"The arrow of this constellation points towards the star Antares, the "heart of the scorpion," and Sagittarius stands poised to attack should Scorpius ever attack the nearby Hercules, or to avenge Scorpius's slaying of Orion.[7]"[1]

"As of 2002, Sun appears in the constellation Sagittarius from 18 December to 18 January."[1]

The shape, size, and to some extent its location as a constellation has changed over time. The second figure at right is an earlier version.

Also, in the Wikipedia article is a list of stars in Sagittarius.

Searching catalogs[edit]

In the lecture/article ultraviolet astronomy in its science section is a list of older catalogs of ultraviolet sources. Using the constellation description in the previous section and the range of coordinates for the constellation in source astronomy, scan through the coordinates for these ultraviolet sources to see if any may be within Sagittarius.

If you find any that are, skip down to the section ultraviolet sources in Sagittarius and make an entry. Be sure to check the coordinate era, most B1950 coordinates have changed slightly to the new J2000 set. Try the catalog designation at either SIMBAD website.

Testing a source[edit]

There are many web sites that may have an ultraviolet source listed for the constellation Sagittarius. Some that you may wish to try are in the External links section near the bottom of this lesson.

Wikipedia sources[edit]

A. Constellation article

Under "Notable features" in the Wikipedia article on the constellation Sagittarius is the list of stars in Sagittarius. Click on this link. In the table of this Wikipedia article is Alrami and Rukbat (α Sgr). To the right are coordinates:

Right ascension (RA): 19h 23m 53.15s and Declination (Dec): -40° 36' 56.3".

Find these coordinates on the Sagittarius map at the right.

To evaluate the star as a ultraviolet source, skip ahead to section "ultraviolet sources".

B. Wikipedia search

Another way to look for ultraviolet sources in the constellation is to perform a search on Wikipedia. Try "ultraviolet sagittarius" without the quotes. This yields 25 returns which include the New Horizons, which is heading in the direction of the constellation Sagittarius, and several entries that mention Sagittarius and ultraviolet.

Scroll down the list of 25 looking for some clear text stating that an ultraviolet source in Sagittarius is discussed, like NGC 6822.

When you find one, skip ahead to the section "ultraviolet sources".

SIMBAD sources[edit]

Another way to find possible ultraviolet sources in Sagittarius is to use search queries on SIMBAD.

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

In the tan box, type in "region(19 23 53.15 -40 36 56.3,10m)", 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 Sagittarii, or Rukbat, with a radius of 10 arcminutes (10m), or try 10d for 10 degrees.

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: 6" should appear. Click "Back" to see the tan box again.

Adding an object type such as & otype='UV' to the region request reduces the returned number to those that are ultraviolet sources, one within 10 m of alpha Sagittarii. Using 10d instead with & otype='UV' yields 280 ultraviolet sources. But, all of the otypes listed at Object classification in SIMBAD may contain ultraviolet stars, yet may not state that any are ultraviolet sources.

Using only otype='UV' yields 91216 UV sources in SIMBAD.

The SIMBAD criteria search allows you to specify spectral types for possible stars. The criteria "sptype" (the exact spectral type): returns only the objects having the requested spectral type (i.e. sptype = 'k0' does not return 'K0III',...). And, "sptypes" should be used to retrive all objects having a spectral type containing the one specified; i.e., sptypes = 'K0' will return all objects having 'K0' as a spectral type, but also 'K0III' or 'K0IIIp', ...). This may also be comgined using an "&" to pick sources you might like.

Here again no information about possible ultraviolet sources may be listed. You have to click on one of objects in the list.

If a flare star is a likely source of ultraviolet waves, which it may because flares also generate ultraviolet rays, then entering otype='Fl*' should locate likely ultraviolet sources.

Using only otype='Fl*' on SIMBAD yields 2582 in all of SIMBAD.

Using otype='UV' & otype='Fl*' yields 105 in all of SIMBAD.

SAO/NASA Astrophysics Data System[edit]

In the naming of sources per constellation, the genitive is in common use. For Sagittarius, the genitive is Sagittarii.

Click on the SAO/NASA Astrophysics Data System link below in the "External links". Try "Sagittarius ultraviolet" without the quotes, "Rukbat ultraviolet", or "alpha sagittarii" with quotes, followed by ultraviolet. The first returns 644 primary source articles that may contain ultraviolet sources in Sagittarius. The second returns zero.

Click on a link below # Bibcode Authors. If the Abstract describes the detection of ultraviolet waves from a source in the constellation Sagittarius, go to the next section under "SAO/NASA Astrophysics Data System".

If it does not try another bibcode link.

Ultraviolet sources[edit]

There are several ways to evaluate a ultraviolet source for the constellation Sagittarius.

Wikipedia sources[edit]

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 ultraviolet waves. Does the article mention whether or not the source is a ultraviolet 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 25 December 2013 at 20:12." 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 ultraviolet source in Sagittarius edit the "Non-ultraviolet sources in Sagittarius" section near the bottom of the page with an entry similar to "# Alpha Sagittariuse 25 December 2013 at 20:12 Wikipedia article "Alpha Sagittarii", without the 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 ultraviolet source in Sagittarius edit the section below "ultraviolet sources in Sagittarius" with a similar entry.

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

From the lecture/article on ultraviolet astronomy, the ultraviolet radiation band may not have an appropriate wavelength temperature pair.

Is the primary star of alpha Sagittarii a ultraviolet star, or a ultraviolet source?

Wikimedia commons[edit]

Another possible website for ultraviolet sources is Wikimedia Commons. Try entering "ultraviolet Sagittarius" without the quotes.

This returns the one image at the top of the page, plus five others that may not be ultraviolet images.

SIMBAD sources[edit]

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, "19 23 53.17483 −40 36 57.3705".

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

Having SIMBAD list all of its 2582 flare stars produces an apparently formidable task. Try searching with your browser using "Sgr".

Many of the flare stars listed do not include a constellation designation. Letting SIMBAD plot all of these flare stars and comparing the plot with the constellation sky chart may help.

There are over 91,000 otype='UV' listed in SIMBAD. Plotting them may be helpful or scanning them using -40, per the example, with your browser may eventually reveal at least one ultraviolet source.

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

SIMBAD time stamp[edit]

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 ultraviolet source, edit the "Non-ultraviolet sources in Sagittarius" 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 may have found a ultraviolet source in Sagittarius (did you check the coordinates vs. the map of Sagittarius?), make an entry something like the ones in the section "ultraviolet sources in Sagittarius".

SAO/NASA Astrophysics Data System sources[edit]

If the abstract states that a ultraviolet source in Sagittarius is detected or studied, consider entering it in the section "ultraviolet sources in Sagittarius" below.

Abstract time stamp[edit]

On the abstract page is a Publication Date:. This may serve as a time stamp for establishing that the source is detected as a ultraviolet source on or before the date of publication. The time stamp followed by four ~s for your verification as determiner in the section "ultraviolet sources in Sagittarius" completes your entry.

Challenging an entry[edit]

Any entry in either the section "Ultraviolet sources in Sagittarius" or "Non-ultraviolet sources in Sagittarius" can be challenged. The time stamp can be challenged to see if there is an earlier one. The source can be challenged by an earlier source.

Wikipedia challenges[edit]

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 ultraviolet source?

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

SIMBAD challenges[edit]

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 ultraviolet source within the constellation on SIMBAD, the next step is to find the earliest time stamp of discovery.

SAO/NASA Astrophysics Data System challenge[edit]

Is the SAO/NASA Astrophysics Data System abstract entry a primary source?

The SAO/NASA Astrophysics Data System is an astronomical database provided by the High Energy Astrophysics Division at the Harvard-Smithsonian Center for Astrophysics of Harvard University. The abstract has been copied from the actual article in a scientific journal or other publication. Mistakes can be made and the article may record within its text exact dates when the observation or detection of millimeter waves actually occurred. Such a record may provide an earlier time stamp.

Primary sources[edit]

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 sources[edit]

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 ultraviolet waves to see if the source has a reference indicating it is a ultraviolet source source. And, look for the earliest one. Compose an entry using the primary source.

SIMBAD test sources[edit]

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

On the page that appears 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 "ultraviolet sources in Sagittarius". 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.

SAO/NASA Astrophysics Data System sources test[edit]

Click on either the "Electronic Refereed Journal Article (HTML)" or "Full Refereed Journal Article (PDF/Postscript)", if available.

Depending on the article display, if the abstract is repeated and the article is listed as FREE, click on either the PDF or HTML version.

While scanning or reading the article look for "Observations" (or use the Find function of your browser) and the possible inclusion of dates for these. If more than one ultraviolet source in Sagittarius are detected, which one(s) would you list in the section "ultraviolet sources in Sagittarius" below?

An example of an article reference is provided in that section.

Changing an entry[edit]

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

If you have found an earlier time stamp for the source than the one listed in the section below "Non-ultraviolet sources in Sagittarius" 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.

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

Ultraviolet sources in Sagittarius[edit]

  1. "This is a single-lined spectroscopic binary system. The ROSAT All Sky Survey discovered that Alpha Sagittarii is emitting an excess flux of X-rays, which is not expected to originate from a star of this spectral class. The most likely explanation is that the companion is an active pre-main sequence star or else a star that has just reached the main sequence.[8]"[9] SIMBAD lists * alf Sgr as UV (TD1) a B8V.

Non-ultraviolet sources in Sagittarius[edit]

Oldest record[edit]

SIMBAD annotations[edit]

For any particular source, the SIMBAD record may indicate that it is not a ultraviolet source yet above you may have found at least two refereed journal articles to indicate that it is. Use the second SIMBAD External links to directly display the SIMBAD database in France.

Enter the name source you have found into the search box. Scroll down to the Annotations :. Look for the link "add an annotation to this object". With browser open to the literature citations available, click on this link. You may need to register as a user. It's free. Post your annotation containing the literature references.

Hypotheses[edit]

Main source: Hypotheses
  1. The first ultraviolet source in Sagittarius was probably discovered around 200 b2k.

See also[edit]

References[edit]

  1. 1.0 1.1 1.2 1.3 1.4 1.5 Lua error in Module:Citation/CS1 at line 3505: bad argument #1 to 'pairs' (table expected, got nil).
  2. Page 15 of Origins of the ancient constellations: I. The Mesopotamian traditions, by J. H. Rogers
  3. Gavin White (2008). Babylonian Star-lore. Solaria Pubs. p. 155. 
  4. 4.0 4.1 4.2 4.3 Ian Ridpath (1988). Star Tales. James Clarke & Co.. pp. 112–114. ISBN 9780718826956. 
  5. Patrick Moore (CRC Press 2010) The Data Book of Astronomy, p. 433 (ISBN 9781420033441.)
  6. Theony Condos, Ph.D. (Red Wheel/Weiser 1997) Star Myths of the Greeks and Romans: A Sourcebook, p. 186 (ISBN 9781609256784.)
  7. Milton D. Heifetz (Cambridge University Press 2004) A Walk Through the Heavens: A Guide to Stars and Constellations and Their Legends, p. 66 (ISBN 9780521544153).
  8. Hubrig, S.; et al. (June 2001). "Search for low-mass PMS companions around X-ray selected late B stars". Astronomy and Astrophysics 372: 152−164. doi:10.1051/0004-6361:20010452. 
  9. Lua error in Module:Citation/CS1 at line 3505: bad argument #1 to 'pairs' (table expected, got nil).

External links[edit]

{{Astronomy resources}}{{Principles of radiation astronomy}}