NGC 1530By Cole Treyturik

2

SECTION 1Introduction

3Introduction

• Name: NGC 1530• Type: Barred Spiral Galaxy[1]

• SBb

• Co-Ords:[2]

• J2013.04 (January 15th, 2013):Right Ascension: 4h 25m 5sDeclination: +75º 19' 46”

• J2013.13 (February 15th, 2013):Right Ascension: 4h 25m 5sDeclination: +75º 19' 47”

• J2013.20 (March 15th, 2013):Right Ascension: 4h 25m 6sDeclination: +75º 19' 47”

4Introduction

• Apparent Magnitude: m=12.00[2]

• Size: 0º 4' 54” [2]

• Angular Size:[1]

• Major Axis: 3.287' = 197.2”• Minor Axis: 1.315' = 78.9”• Area (A): 15560.7”2

• Surface Brightness:• = 22.5 (mag / ”2)

• Physical Size:[3]

• Major Axis: 36.65 kpc• Minor Axis: 14.66 kpc

5Introduction

NGC 1530 is located within the constellation of Camelopardalis[4]

Image taken using Stellarium

6Introduction

NGC 1530 is located within the constellation of Camelopardalis[4]

Image taken using Stellarium

7Introduction

Optics 24-inch RC Optical Systems Telescope[5]

Camera SBIG STL11000 CCD Camera[5]

Filters Custom Scientific[5]

Dates November 20th 2009[5]

Location Mount Lemmon SkyCenter[5]

8Introduction

Optics FS-128 (ag, ST-4)[6]

Camera ST-2000XM LRGB 15 minute subs[6] Filters UnknownDates December 2006[6]

Location Penryn, California[6]

9Introduction

• Over 100 million light-years away[7]

• One of the largest barred spiral galaxies in the Northern Hemisphere[7]

• One of the “strongest” bars observable[7]

• Rare double-spiral formation[7]

10

SECTION 2Data + Observations

11

Data + Observations

• Observations were made on the night of 28/02/2013 – 01/03/2013• Conditions for the night were quite good• Temperature: -9ºC• Darkness: 4/5• Seeing: 4.5/5• Transparency: 4/5• SQM Readings: 20.12, 20.13, 20.12• Clouds: ~10% cover• Wind: Little-to-none• Humidity: Low• Moon phase: Waning Gibbous, mostly full (did not rise until ~23:00 CST)• Start of Astronomical Twilight: 19:57 CST[8]

12Data + Observations

Master bias frame from the night, created using ImageJ

13

Data + Observations

Master dark frame from the night, created using ImageJ

14

Data + Observations

Master flat frame from the night, created using ImageJ

15

Data + Observations

Processed image from the night, created using ImageJ

16

Data + Observations

Processed image from the night, created using ImageJ

17

Data + Observations

Processed image from the night, created using ImageJ

18

Data + Observations

• Creation of the final image followed the normal steps, for the most part:• Subtraction of the master bias, master dark from the individual images• Division of the individual images by the master flat

• Around 1/3rd of the frames were significantly brighter than the rest, likely due to a wandering cloud• All images were then averaged out to an average pixel value of 900.

• Images were aligned using the “StackReg” plugin• Images were then cropped, and combined using the “Average

Intensity” setting of Z-Project.

19

Data + Observations

Final, fully processed image from the night, created using ImageJ

20

SECTION 3Research + Knowledge

21

Research + Knowledge

• Paper: “The Mass Inflow Rate in the Barred Galaxy NGC 1530”• Michael W. Regan, Stuart N. Vogel, Peter J. Teuben

• University of Maryland• Submitted to the Astrophysical Journal Letters on July 17, 1996[9]

• Accepted on March 31 1997[9]

• Published online on April 1, 1997[10]

• In print June 20, 1997 in Volume 482, Issue 2 of Ap J Letters[9]

• http://arxiv.org/abs/astro-ph/9704009

22

Research + Knowledge

“Mass inflow in barred galaxies has been invoked to account for a wide variety of phenomena, but until now direct evidence for inflow has been lacking. We present Fabry-Perot H-alpha observations of the barred spiral galaxy NGC 1530 from which we determine velocities of the ionized gas for the entire region swept by the bar. We compare the velocity field to models of gas flow in barred spirals and show that it is well reproduced by ideal gas hydrodynamic models. Inspection of the models and observations reveals that gas entering the bar dust lanes streams directly down the dust lanes toward the 2 kpc radius nuclear ring. The models predict that approximately 20% of the gas flowing down the dust lane enters the nuclear ring; the remaining gas sprays around the ring to the other bar dust lane. The fraction of the gas entering the ring is relatively insensitive to the shape or size of the bar. Our observations of the velocity field and dust optical depth yield a mass inflow rate into the nuclear ring of 1 solar mass per year.”

23

Research + Knowledge

• To summarize the abstract, mass flowing into the centre of barred galaxies had been used as an explanation for several phenomena, but without any direct observations

• By comparing models of the velocity of gasses within and without the bar to observations of such, the rate of gas flow into the centre can be calculated

24Aside

• What is a “bar?”• Galaxies come in several different types• Elliptical, spiral, irregular

• The “spiral” classification contains two subtypes• Barred and non-barred

• A spiral galaxy is classified as “barred” when its spiral arms sprout out of a “rectangular” formation rather than the nucleus• This formation is known as the “bar” of a galaxy

• It is thought that these bars fuel star formation via channeling gasses inwards

25

Research + Knowledge

• Because of its highly pronounced bar and the angle it makes to us, NGC 1530 makes a great target for such observations

• Using Fabry-Perot measurements of the galaxies’ Hα lines, it was possible for the authors to obtain kinematic values for the galaxy

26Aside

• What is “Fabry-Perot?”• A Fabry-Perot interferometer (sometimes referred to as an etalon) is

a highly sensitive optical system• They are commonly used in astronomy as a spectrometer, due to the

fact that they are able to easily view single atomic transition lines – such as the Hα line

• They use interference to enhance the subtle difference in wavelengths of detected light

27

Research + Knowledge

• The observations used for this report were made on the night of 30/09/1994 – 01/10/1994, at the Palomar Observatory

• Telescope used was the 1.5m reflector• Detector instrument used was the Maryland-Caltech Imaging Fabry-

Perot Interferometer• Angular resolution for the night ranged from 4” to 15”

28

Research + Knowledge

• The results from comparing the observations to the model were very favourable - despite the model not being adjusted for the mass or shape of NGC 1530

• It is found that mass is indeed flowing towards to nucleus, along the bars, at speeds of between 85 and 200 km/s• Velocity increases closer to the nuclear ring

• The rate of mass flow was calculated to be 1 (+2 / -0.5) solar masses per year

29

SECTION 4Focus Area

30Focus Area

• Not a widely studied galaxy• arXiv search for “NGC 1530” returns only 16 results

• Only four of those have the galaxy as their main focus

• Chosen paper focuses primarily on kinematics, which cannot be measured with our data• Other topics are touched on, however:

• Axial ratio (ratio of the major axis to the minor axis) of the bar• Physical size of the bar, nuclear ring

31Focus Area

• The axial ratio would be rather simple to measure• In ImageJ, measuring the length of the of the bar vs. the width of the bar

• This, combined with the given nuclear ring radius, could be used to find the physical size of the galaxy• This could then be used to find the distance to the galaxy

• Compare the angular size to the obtained physical size

• Axial ratio could also be used to find the incline of the galactic plane w.r.t. our field of view• Measure the axial ratio of our images, compare to given ratio in paper

32References

• [1]: Simbad Astronomical Database • [2]: Stellarium: Free Planetarium• [3]: NASA/IPAC Extragalactic Database• [4]: DeepSkyPedia• [5]: University of Arizona’s Mount Lemmon

SkyCenter• [6]: Astrophotos.net• [7]: Mano Prieto Observatory• [8]: US Naval Observatory• [9]: IOP Science• [10]: arXiv.org