M77 (NGC 1068) By: Ryan Desautels

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

A Brief History October 29 th, 1780; October 29 th, 1780; First observation made of NGC 1068 by M. Mechain. First observation made of NGC 1068 by M. Mechain. He described it as a nebula He described it as a nebula December 17 th, 1780; December 17 th, 1780; Observed by Charles Messier and catalogued as “Cluster of faint stars, which contains nebulosity…” (Charles Messier, Catalogue). Observed by Charles Messier and catalogued as “Cluster of faint stars, which contains nebulosity…” (Charles Messier, Catalogue). Other notable early observations; Other notable early observations; W. Hershel described M77 as a cluster of stars. W. Hershel described M77 as a cluster of stars. Rosse was the first astronomer to recognize M77 as a galaxy and not a star cluster. Rosse was the first astronomer to recognize M77 as a galaxy and not a star cluster.

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

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

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. Well, according to Gilbert A. Esquerdo and John C. Barentine, there is a barred structure present, at least in IR wavelengths. N W

Bar in optical?

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

Size

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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). 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. 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. Messier 77 has a period of less then a week.

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

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

What are AGN’s As a group, they are the most active galaxies out there. 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. 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. The widely accepted model of an AGN galaxy is that it has a central super massive black hole as it’s engine.

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

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

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

Carl K. Seyfert Pioneered research on nuclear emission in spiral galaxies. Pioneered research on nuclear emission in spiral galaxies he published a paper on galaxies with bright nuclei that exhibit characteristically broadened emission lines 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. 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. Involved in instrumental innovations which included the use of photomultiplier tubes and television techniques in astronomy, and electronically controlled telescope drives.

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

Type 1 Type 1 galaxies have two sets of emission lines in their spectra: Type 1 galaxies have two sets of emission lines in their spectra: Narrow lines, with widths of several hundred km/s Narrow lines, with widths of several hundred km/s Broad lines, with widths of up to 10 4 km/s Broad lines, with widths of up to 10 4 km/s

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

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. 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.

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

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

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

Variability

Variability

Variability

Variability

Variability

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

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

Summary Small region of rapid variability. Small region of rapid variability. Yes, as shown in my graph the brightness does change, and the period of M77 is roughly 1 week. Yes, as shown in my graph the brightness does change, and the period of M77 is roughly 1 week.

Summary High contrast of brightness between nucleus and other structures (large scale). 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. 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.

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

References Images: Images: imgdata?objid=58240&objname=MESSIER% imgdata?objid=58240&objname=MESSIER% imgdata?objid=58240&objname=MESSIER% imgdata?objid=58240&objname=MESSIER% Information: Information: multiwavelength_museum/m77.html multiwavelength_museum/m77.html multiwavelength_museum/m77.html multiwavelength_museum/m77.html Introductory Astronomy & Astrophysics 4 th E., 1998 Introductory Astronomy & Astrophysics 4 th E.,