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M77 (NGC 1068)

M77 (NGC 1068). By: Ryan Desautels. Messier 77. A Brief History General Information Galactic Information AGN Seyfert Research Question Does M77 have a barred structure? Does the brightness change, is it possible to detect this change? Summary. A Brief History. October 29 th , 1780;

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M77 (NGC 1068)

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  1. M77 (NGC 1068) By: Ryan Desautels

  2. Messier 77 • A Brief History • General Information • Galactic Information • AGN • Seyfert • Research Question • Does M77 have a barred structure? • Does the brightness change, is it possible to detect this change? • Summary

  3. A Brief History • October 29th, 1780; • First observation made of NGC 1068 by M. Mechain. • He described it as a nebula • http://www.seds.org/messier/m/m077.html • December 17th, 1780; • Observed by Charles Messier and catalogued as “Cluster of faint stars, which contains nebulosity…” (Charles Messier, Catalogue). • http://www.kopernik.org/images/archive/m77.htm • Other notable early observations; • W. Hershel described M77 as a cluster of stars. • http://www.kopernik.org/images/archive/m77.htm • Rosse was the first astronomer to recognize M77 as a galaxy and not a star cluster. • http://www.kopernik.org/images/archive/m77.htm

  4. General Information • Type • What type of galaxy is Messier 77? • Size • What are some of the dimensions of Messier 77? • Brightness • What is the brightness of Messier 77 and some of its oddities?

  5. Type • NGC 1068 is a spiral galaxy (barred?). • Type Sb using Hubble’s Tuning Fork Diagram. • I will give an argument why this classification is no longer accurate. • Part of a group of galaxies known as Seyfert Galaxies. • Seyfert Galaxies are a subset of galaxies and other objects known as Active Galactic Nuclei (AGN). • M77 is the prototype galaxy for the Seyfert class.

  6. Bar or no bar? • Well, according to Gilbert A. Esquerdo and John C. Barentine, there is a barred structure present, at least in IR wavelengths. W N

  7. Bar in optical?

  8. Size • M77 is slightly larger then our own Milky Way. • M77 has an extent of roughly 170 000 light years with a core (brightest area) that makes up about 71% of it’s total size (120 000 light years). • It is at a distance of approximately 60 million light years.

  9. Size

  10. 120 000ly

  11. Brightness • Messier 77 has a brightness that varies (most observatories and papers classify the brightness somewhere in the range of 8.9 to 10.5). • Brightness variations is a property of Seyfert galaxies. Not only do they vary in brightness, they can also vary in class. • Messier 77 has a period of less then a week.

  12. Brightness • The core of M77 is very similar to that of a star (point source). Which is a property of Seyfert Galaxies.

  13. Active Galactic Nuclei (AGN) • A little background information on AGN’s • What are AGN’s • Are there different types of AGN’s, if so, what are they • Basic properties of AGN’s

  14. What are AGN’s • As a group, they are the most active galaxies out there. • Galaxies who’s nuclei alone produce more radiation then the rest of the galaxy. • The widely accepted model of an AGN galaxy is that it has a central super massive black hole as it’s engine.

  15. Different types of AGN’s • AGN’s are a general class of galaxies • Seyfert Galaxies • Type 1, and 2 • Radio Galaxies • Radio luminosity > 1033 W • Quasars • Very distant AGN’s • BL Lacertae Objects

  16. Basic properties of AGN’s • AGN’s as a group show all or most of the following characteristics. • High luminosity greater then 1037 W. • Nonthermal emission, with excessive UV, IR, Radio and X-Ray flux (compared to most galaxies). • Small region of rapid variability. • High contrast of brightness between nucleus and other structures (large scale). • Broad emission lines (sometimes).

  17. Seyfert Galaxies • First discovered by Carl K. Seyfert. • Messier 77 is the prototype Seyfert Galaxy. • What are Seyfert Galaxies? • What are the different types? • Type: 1,1.5,2 • What do different Seyfert galaxies share in common. • How is M77 a Seyfert Galaxy.

  18. Carl K. Seyfert • Pioneered research on nuclear emission in spiral galaxies. • 1943 he published a paper on galaxies with bright nuclei that exhibit characteristically broadened emission lines. • While at Warner Swasey Observatory and the Case Institute, he obtained the first good colour photographs of nebulae and stellar spectra. • Involved in instrumental innovations which included the use of photomultiplier tubes and television techniques in astronomy, and electronically controlled telescope drives.

  19. Different Types of Seyfert Galaxies • There are two different types of Seyfert Galaxies. NGC 5548 M77 Type 1 Type 2

  20. Type 1 • Type 1 galaxies have two sets of emission lines in their spectra: • Narrow lines, with widths of several hundred km/s • Broad lines, with widths of up to 104 km/s

  21. Type 2 • Object has only narrow lines present.

  22. Why different types • Types 1 and 2 are only different because of our point of view. It is thought that the differences are due to a torus which is preventing us from seeing the broad regions in Seyfert 2 galaxies.

  23. Messier 77’s variability • Is it possible to detect the variability? • If it is possible, what is the range in apparent magnitude?

  24. Variability • To find the variability: • Measure each individual object image. • Set the mean value of each object image ~ 0 • Measure the FWHM of a non-variable star in the field. • Measure an area around the star . • ~ 4x FWHM. • Adjust each image so that the star brightness (mean value) is the same in each object image.

  25. Variability • Measure the FWHM of the galaxy. • Measure an area around the core of the galaxy. • ~ 4x FWHM • Using the formula: • m-n = (2.5)log(Fn/Fm), • Where m-n = the change in brightness, • Fn = the mean value of the star, • Fm = the mean value of the galaxy.

  26. Variability

  27. Variability

  28. Variability

  29. Variability

  30. Variability

  31. Variability • We can see from the previous graph that there is some variability. • There is a change in variability of 0.07. • This change is quite small, however; it is greater then the error so I can say that there is definitely a change in brightness.

  32. Summary • Messier 77 is a Sb Type 2 Seyfert Galaxy. • It satisfies some of the criterion of the AGN model.

  33. Summary • Small region of rapid variability. • Yes, as shown in my graph the brightness does change, and the period of M77 is roughly 1 week. • http://www.kopernik.org/images/archive/m77.htm

  34. Summary • High contrast of brightness between nucleus and other structures (large scale). • Yes, it is only with special filters (Digital Development Processing DDP), that we are able to make out the central bulge area and the rest of the galaxy.

  35. Summary • Messier 77 is a galaxy who’s core has an almost stellar output.

  36. References • Images: • http://www.aao.gov.au/images/captions/aatccd012.html • http://archive.stsci.edu/cgi-bin/dss_form?target=m77&resolver=SIMBAD • http://cas.sdss.org/dr3/en/proj/advanced/galaxies/tuningfork.asp • http://www.noao.edu/outreach/aop/observers/m77.html • http://nedwww.ipac.caltech.edu/cgi-bin/nph-imgdata?objid=58240&objname=MESSIER%20077 • http://www.astrosurf.com/astroduvel/images/m77.html • Information: • http://imagine.gsfc.nasa.gov/docs/science/know_l1/active_galaxies.html • http://www.astr.ua.edu/keel/agn/ • http://www.noao.edu/outreach/aop/observers/m77.html • http://coolcosmos.ipac.caltech.edu/cosmic_classroom/multiwavelength_astronomy/multiwavelength_museum/m77.html • http://seds.lpl.arizona.edu/messier/more/m077_hst.html • http://www.messiermarathon.com/new_page_83.htm • Introductory Astronomy & Astrophysics 4th E., 1998 • http://www.ne.jp/asahi/stellar/scenes/object_e/m77.htm

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