Discovery and Characterization of Galactic Ionized Nebulae with WHAM Peter Doze, Texas Southern University Advisor: Dr. Bob Benjamin University of Wisconsin-Madison National Astronomy Consortium Finkbeiner (2003)

The Wisconsin H-alpha Mapper (WHAM) Wisconsin H-Alpha Mapper (WHAM) detects faint optical emission lines from the diffuse warm interstellar medium. —One-degree beam —Velocity baseline of ~200 km/s —Velocity resolution of 12 km/s Much of the sky was observed from Kitt Peak (Haffner et al 2003); the southern sky is currently being observed from Cerro-Tololo observatory. This is the FIRST velocity resolved all-sky survey of H-alpha emission. The major goal is to characterize the diffuse ionized gas. I worked on the properties of the brighter ionized nebulae.

Ionized Nebulae in the “Warm Ionized Medium” (WIM) To date Started off by searching for bubbles/ionized regions in a combined H-alpha image from Finkbeiner (2003) using data from Southern H-alpha Sky Survey Atlas (SHASSA Gaustad et al 2001), Virginia Tech Spectral survey (VTSS, Dennison et al 1998) and WHAM. We had 758 H-alpha nebulae total and 105 new (uncatalogued?) regions.

HII Regions=Ionized Nebulae? Regions characterized by Hα emission Photo-ionized by UV or X-ray photons. If UV sources is O or B stars (T~40,000K), usually called a “HII region” Ionized region=“Strömgren Sphere” H-alpha produced by “recombination” Schematic showing Bohr radius/quantum number of hydrogen atoms

Analysis of the Identified Bubbles A test case-The Circinus Bubble Diameter of ~5 degrees 5 degrees diameter Distance constrained by CO (molecular) cloud in lower right absorbing the optical emisison. Distance to cloud is 435 pc (Knude 2010) and the cloud has active star formation. Bubble center is at z=-20 pc (below midplane) Bubble radius is 20 pc. Possible Ionizing sources: HD (O8.5 V) and HD (O8 III p) H-alpha flux consistent with UV photons expected from these stars.

Looking at intensity vs. radius

Automating this process for 278 nebulae! After practicing with the Circinus HII region, we made a list of ALL bubbles with at least one WHAM beam center inside the bubble. Created a table of the direction, angular radius, number of WHAM beams, total intensity, and average first and second velocity moments. With this we were able to calculate the Galactocentric Radius and the distance from the Sun

The red figure is a histogram of physical sizes, calculated with the angular radius and the distances calculated. The blue figure is a histogram of the SII/H alpha ratio and the vertical black line is the average. The green figure is a histogram of the linewidths of the HII regions

Map of HII Regions The Orange dots are known HII regions and the Red dots are the uncategorized HII regions.

Results We have used the H-alpha compilation image of Finkbeiner (2003) to create a master catalog of H-alpha bright regions consisting of 738 objects, of which 105 are apparently not cataloged yet. We examined in detail the distribution of the intensity and first and second velocity moments for a selected set of bubbles, in particular the (uncataloged) Circinus bubble. We have generated a table of kinematic distances, intensites, velocity moments and (when available) [S II]/H-alpha line ratios for 278 objects with bubbles containing WHAM pointing centers. Future work: validation of the table results and comparison with previous velocity measurements when available.

University of Wisconsin-Madison NAC Lows There were only two NAC students on site. I feel that this made it harder to follow the NAC outline because the majority of students where regular REU students.

University of Wisconsin-Madison NAC Highs The supportive master/apprentice relationship contributed to my success during the summer. When I hit a wall (IDL) I could always quickly access my personal mentor or the other mentors on site for help. Another consequence of the NAC’s mentorship is my visit to Kitt Peak to observe on the 0.9m telescope. I was able to operate all aspects of the telescope including tracking, file management, and filter selection.

Rgal Joachim Köppen Kiel (2014)