news on the optical and radio variability of mwc349 gary walker coauthors: elissa sperling, reu...
TRANSCRIPT
News on the Optical and Radio
Variability of MWC349 Gary Walker
CoAuthors: Elissa Sperling, REU Wesleyan Margaret Danielson, RET Nantucket
&Dr. Vladimir Strelnitski
AAVSO Meeting, October 17, 2008
Abstract:
The results of the long-term (11 years) monitoring of MWC349 at optical and radio wavelengths, as well as a recent (summer 2008) experiment of simultaneous optical and radio observations to detect short-term variability, will be summarized. In particular, we will compare the results obtained with the 24-inch CCD telescope of the MMO with those submitted to the AAVSO database by various observers. The revealed amplitudes of MWC349 variations are small – a few tenths of a magnitude for a long-term variations (years) and, typically, less than one tenth for the short-term variations (months to days). This requires a relatively high accuracy photometry, not always achieved in amateur observations. The data obtained so far can be summarized as follows: (1) No obvious periodicity; (2) The amplitude of variations monotonically decreases with the decreasing time scale and towards longer wavelengths; (3) There is correlation of optical (R) and radio (hydrogen recombination line maser) radiation on both a long and short time scales, but the amplitude of the radio variations is greater. Possible interpretation of these results will be discussed. This project was supported by the NSF/REU grant AST-0354056 and the Nantucket Maria Mitchell Association.
Maria Mitchell Association/Observatory
• MMA—10 Buildings, 24 Summer Interns, Astronomy, Natural Science, Education, Marine Science, Library, Curation
• MMO—Astronomy Department– Director Dr. Vladimir Strelnitski
– Telescope Engineer and Astronomer Gary Walker
– Original Prototype of REU Program Started by Dorrit Hoffleit
– 6 Astronomy Majors every Summer are Taught Research
– All write Posters for AAS Meeting in January
– 100 Applicants—Harvard, Columbia, Swathmore, BU, Berkley, Rice
– Projects cover Radio, Optical Observational, and Theoretical
– Prest Grant and Vladimir’s Energy have made MMO a Premier Program
40’ South of the Cyg OB2 center: MWC 349
MWC 349
Comparison Star 134 N
CK4--137
CK1--128
CK2--134
CK3--119
It has been observed in…
• Visible - emission line star (MWC 349)- variable star (V1478 Cyg)
• IR - neutral gas/dust edge-on disk
• Radio, mm, sub mm- ionized disk and outflow; masers and lasers in hydrogen recombination lines
-0.2
-0.1
0
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50500 51000 51500 52000 52500 53000 53500Julian Date (-2400000)
Mag
nitu
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I
R
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R
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V
Plan (and Proposal) for 2007-08:
MMO plan• Intensify parallel visible and radio monitoring
• Include Hα and IR monitoring
• Observe lasing mid-IR rec. lines from SOFIA and possible X rays from CHANDRA
Proposal• Personal collaboration or making MWC 349 an AAVSO “Star of the Year” for 2007-2008
• Summarize all the results at the AAVSO annual meeting in Nantucket, October 2008 (MMO’s Centennial)
Haw--MWC349--Summer 08
y = 7E-06x2 - 0.0624x + 155.63
R2 = 0.8417
11.35
11.40
11.45
11.50
11.55
11.60
11.65
11.70
11.75
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HD - 2450000
Dif
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MWC349 C124 Avg - 3.05 ( Linear)C 124 Avg -3.05 (Poly) .MWC349
R--MWC349_Summer 08
y = 5E-06x2 - 0.05x + 125.49
R2 = 0.7299
10.55
10.60
10.65
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10.75
10.80
10.85
10.90
10.95
11.00
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JD - 2450000
R--
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MWC349 Ck Ensemble Avg - 1.15 (Poly) .MWC349 ( Linear) Ck Ensemble Avg -1.15
Ri--MWC349--Summer 08
y = -1E-05x2 + 0.1124x - 247.7
R2 = 0.2963
13.65
13.70
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13.80
13.85
13.90
13.95
14.00
14.05
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JD - 2450000
Dif
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Series1 Series2 ( Linear)Series2 (Poly) .Series1
Haw and Han Comparison; MWC 349
y = -0.0002x + 11.838
R2 = 0.0272
y = 0.0018x + 2.0415
R2 = 0.7021
y = 0.0023x - 0.3151
R2 = 0.9008
10.40
10.45
10.50
10.55
10.60
10.65
10.70
10.75
10.80
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JD - 2450000
Dif
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ag
Han Ck124 Avg Haw CK 124 Avg ) Linear(Ck 124Avg ) Linear(Haw ) Linear(Han
Comparison of Flat Fielding
y = 0.0024x - 0.6306
R2 = 0.9179
y = 0.0023x - 0.3151
R2 = 0.9008
10.52
10.53
10.54
10.55
10.56
10.57
10.58
10.59
10.60
10.61
10.62
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JD - 2450000
Diff
erenti
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Mag
Han Raw Han FF ) Linear(Han FF ) Linear(Han Raw
AAVSO V Data; MWC349
y = 1E-05x2 - 0.0901x + 221.53
R2 = 0.386
12.75
12.80
12.85
12.90
12.95
13.00
13.05
13.10
13.15
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JD - 245550
V D
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Mag
MWC349 Poly. (MWC349)
Data Courtesy AAVSO & Observer Robert James
Air Mass During MWC349 Observations
0.0
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JD - 2450000
Air
Ma
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Air Mass Durring MWC Observations
Air Mass During MWC349 Observations
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JD - 2450000
Air
Ma
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Air Mass Durring MWC Observations
Air Mass Calculator Courtesy Bruce Gary, AXA web site
Possible Spectra
617
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619
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623
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627
550 570 590 610 630 650 670 690 710 730
Wavelength (nm)
Re
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Early Summer08 End of Summer 08
Haw & HanRi
Conclusions
• Work in Progress
• Need Nightly Spectra
• May monitor in Sii—(672nm)
• Try Simultaneous Radio and Optical monitoring
• Look at other objects with Ri (645nm) Band
Conclusions
• MWC349 is a unique young object in a transitory evolutionary state (102-103 yrs)
• Masing lines are highly variable indicating fast variations of the central object or local conditions in the disk
• Optical continuum probes the nature of the central object and its closest environment; shows now a secular decline and possible periodicity (a binary? magnetic cycle?)