Advisors: Greg Doppmann and Bernadette Rodgers NSF CTIO REU 2006. Spectroscopic Investigation of Companion Stars in Herbig Ae/Be Binary Systems Anne Sweet. Introduction:. What are Herbig AeBe Stars? -Pre-Main Sequence (PMS) - 2 < Msun < 8 -associated with a star forming regions
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NSF CTIO REU 2006Spectroscopic Investigation of Companion Stars in Herbig Ae/Be Binary SystemsAnne Sweet
What are Herbig AeBe Stars?
-Pre-Main Sequence (PMS)
- 2 < Msun < 8
-associated with a star forming regions
-IR excess and/or emission lines
Why are we studying these systems?
-binary fraction and the initial mass function
-possibility of direct mass measurement
-stellar evolution as a function of mass
-the effects of PMS Herbig stars on the evolution of low mass counterparts --> HR diagram
Why are we using the IR?
-environments associated with Young Stellar Objects (YSOs) make the IR the most effective and ideal waveband
-Herbig stars with known companions and a binary separation of less than 0.8''
-MK Standards: GNIRS 111 1/mm grating, R =18,000
-CO Ori A and B: 32 1/mm grating, R=1,800
-HR 5999B: GNIRS 111 1/mm grating, R =18,000
-BF Ori B: GNIRS 111 1/mm grating, R =6,000
-images reduced in IRAF
-telluric correction applied using xtellcor in IDL
Two methods used, both utilizing the Ames models (Hauschildt 2003-private communication)
1) High Resolution Analysis (R=18,000)
-matches spectral synthesis models with data to find the best pixel to pixel fit across absorption lines (Na lines at 2.2 microns, CO bandhead at 2.3 microns)
-used with: MK standards, HR5999B (Na only), BF Ori B (Na only)
2) Medium Resolution Analysis (R=6,000)
-overplots models on data for a qualitative eye fit
-uses equivalent widths of models and data for a quantitative comparison.
-used with CO Ori A and B and BF Ori B.
For both methods, data must be late type!
-Using Na and CO portions of the spectra.
-Process (Doppmann 2003):
-input .txt file
-select relevant region
-input a specific value for log(g), and give a range of values for vsini, shift and Teff.
-iterate to minimize RMS
-8 standards, K0-M0.5, luminosity class III
-used for calibrating technique to literature
-well correlated, but systematically offset from published data
-other models were considered, but discarded due to limited atmospheres.
-We applied two fits with different fixed logg values for a decent result- useful for comparison with medium resolution result.
-Program overplots models on data for a qualitative fit comparison
-with the generated models, measure equivalent widths of strong lines and compare to equivalent widths of data.
-Na lines of BF Ori B shown on left, note changes in lines with increasing temp.
10 strong lines chosen across 5 different orders (Na, Ti, Al)
Green: Logg=3.5, Blue: Logg=4.5, red: EQW of data with errors
-put these results on an H-R diagram!!
-by identifying spectral type, identify how many are late-type and compare to the T Tauri stars (PMS without nearby Herbig star) to say something about the effect that a massive star has on low mass stellar formation.
-Questions this brings up....
-Greg and Bernadette for being fantastic mentors (and Peter for always trying to give me the day off)
-Stella, best REU mom EVER
-the other REUers for breaking the harassment/decency code JUST about every day.
-NSF for this wonderful research opportunity!!