The open cluster ngc 7129 Joshua thomas

Overview Intro to the reflection nebula NGC 7129 Facts and Images GAO Data Stellar Formation in NGC 7129 Spitzer Analysis

NGc 7129 Open cluster in the constellation of Cepheus Large molecular cloud and area of dense star formation Contains multiple herbig haro objects or star formation jets RA/Dec: 21h 42m 56s / +66 6’ 12” Image Courtesy: T. A. Rector/University of Alaska Anchorage, H. Schweiker/WIYN and NOAO/AURA/NSF

Pretty pictures Image Courtesy NASA/JPL-Caltech/T. Megeath (Harvard-Smithsonian CfA) Image courtesy Leonardi Orazi (2009-2013)

Fun facts and images Has been described as “singularly unimpressive” as a “small group of half a dozen dim stars” (R. Thompson & B. Thompson, 171)2 Contains 3 herbig-haro objects which are emitting large jets of gas into the cloud Contains 47 young stellar objects as identified by B. Stolzer & A. Scholz1 Left: 2MASS survey J band. Right: WISE 3.4 micron surevey

Our data Observations of the cluster NGC 7129 conducted on January 21, 2016, 19:50-20:20 CST at the Glenlea Astronomical Observatory Basic greyscale processed image of NGC 7129 from GAO

Observation conditions Seeing was a bit below average Although cloud cover was at a minimum, the moon was nearly full and very bright SQM read a quality of 17.47 when observations started Throughout the observations the light level fluctuated significantly likely due to the moonlight

Typical dark sky flat from GAO Our dark sky master flat from GAO

Image processing There were a few issues with our raw data Primarily that of the dark sky flat shown previously Even the actual science images contained highly varying brightness levels We also had to omit a few frames of the raw data set (frames 29, 38, 39) which were found to be blurry or unacceptable Image at end of night Image at beginning of night

Top row: Our own processed images in greyscale, and other color lookup tables Bottom row: Processed spitzer 3.6 micron IRAC data in greyscale and color scheme

Research background In the optical spectrum the cluster is generally unimpressive Only in the X-ray and IR spectrum does it become more interesting It is through an examination of these wavelengths that NGC 7129 was found to be a region of dense star formation with many young forming stars Herbig-Haro object Image courtesy J. Morse/STSci and NASA

Stellar formation Star formation begins when an interstellar cloud begins to collapse due to gravity The point to which the gas converges becomes extremely hot as a result Eventually this can turn into the beginnings of a star or ‘protostar’ This results in a dense protostar core surrounded by a swirling cloud of hot gas It is this abundance of hot gas that causes the stars spectrum to shift more toward the infrared

Protostar detection This excess dust and gas causes the star to emit more so in the infrared spectrum then other main sequence stars The forming star will emit more infrared radiation then would be expected from just a black body radiator This is known extra radiation from the surrounding dust is known as ‘infrared excess’

Protostars in ngc 7129 When the Spitzer telescope made its observations of the cluster it found strong infrared emissions This was then further analyzed by B. Stelzer and A. Scholz in their article “A Chandra and Spitzer census of the young star cluster in the reflection nebula NGC 7129”1 By means of a “color-color” graph Stelzer & Scholz (2009) were able determine a large quantity of YSO’s in the cluster. They were even able to classify these into two different types

Radio Spectroscopy For the Spitzer data analysis Stelzer and Scholz (2009) made use of 4 different wavelengths observed by the Infrared Array Camera (IRAC). This included observations in 3.6, 4.5, 5.8 and 8.0 microns The comparison of magnitude to observed wavelength is a color-color graph

Color-color graphs Image from B. Stelzer & A. Scholz (2009)1

Focus area: Spitzer analysis The spritzer IRAC survey raw data is in the form of many 5.2’ x 5.2’ field of view images In order to properly analyze the data these must be combined in a mosaic It is with a combination of all 4 wavelength mosaic images that analysis can be performed In order to create the image to the right I made use of the program ‘Montage’ which compiles and arranges image sets Spitzer 4.5 micron raw frame

colorizing Each wavelength image can then be assigned a color either arbitrarily or based upon the radiation energy The combination of these frames is then the composite color image For my project I did this combination in multiple different color combinations and programs as shown

Composite examples Colored spritzer data with Red = 8.0 μm Yellow = 6.8 μm Green = 4.5 μm Blue = 3.5 μm Colored Spitzer data with Red = 8.0 μm, Green = 4.5 μm Blue = 3.5 μm

Spitzer and 2MASS data with the 2MASS J Band in blue and Spitzer 8 Spitzer and 2MASS data with the 2MASS J Band in blue and Spitzer 8.0micron in red Combination of all 3 2MASS images and 4 Spitzer with red being the highest wavelength and blue the smallest

Sources 1Scholz A, Stelzer B. 2009. A Chandra and Spitzer census of the young star cluster in the reflection nebula NGC 7129. A&A. 507(1):227-40 IRAC Instrument and Support Team. 2015. IRAC Instrument Handbook. Allen LE, Fazio GG, Gutermuth RA, Megeath ST, Myers PC, Pipher JL. 2009. A Spitzer Survey of Young Stellar Clusters within one Kiloparsec of the Sun: Cluster Core Extraction and Basic Structural Analysis. ApJS. 184:18-83. Eiroa C, Gomez de Castro AI, Miranda LF. 1992. New Herbi-Haro objects and pre-main sequence stars in the star formation region of NGC 7129. A&A. 271:564-73. 2Thompson RB, Thompson BF. 2007. Cepheus: The King. Illustrated Guide to Astronomical Wonders. Jepson B. pp 171. NASA Science Astrophysics. 2016. Stars. http://science.nasa.gov/astrophysics/focus-areas/how-do- stars-form-and-evolve/