getting precise stellar parameters in plato’s first field
DESCRIPTION
Getting Precise Stellar Parameters in PLATO’s first field. PLATO science conference 24/25 th Feb 2011. T. Granzer, K.G. Strassmeier, & M. Weber. A dedicated input catalog?. Dedicated photometric characterization survey in Strömgren uvby n w and H - PowerPoint PPT PresentationTRANSCRIPT
![Page 1: Getting Precise Stellar Parameters in PLATO’s first field](https://reader035.vdocuments.net/reader035/viewer/2022062516/56814a86550346895db798fc/html5/thumbnails/1.jpg)
Getting Precise Stellar Parameters in PLATO’s first field
PLATO science conference 24/25th Feb 2011
T. Granzer, K.G. Strassmeier,
& M. Weber
![Page 2: Getting Precise Stellar Parameters in PLATO’s first field](https://reader035.vdocuments.net/reader035/viewer/2022062516/56814a86550346895db798fc/html5/thumbnails/2.jpg)
• Dedicated photometric characterization survey in Strömgren uvbynw and H
• Deliverables: (b-y), c1, m1, Teff, [M/H], log g; Flux F(H) down to 13mag.
• Constraints: bright limit 9.5, faint 16mag
• First field (fixed) in southern hemisphere
• Challenge: 2000 □2
A dedicated input catalog?
![Page 3: Getting Precise Stellar Parameters in PLATO’s first field](https://reader035.vdocuments.net/reader035/viewer/2022062516/56814a86550346895db798fc/html5/thumbnails/3.jpg)
Challenge: 2000 sq-deg
• Super Wasp-South (SAAO), 8x11.1cm lens optics, FoV 7.8x7.8º,~35 pointings, filters ‘on demand’ (?)
• OmegaCam@VST (Paranal): 2.6m Ritchey-Crétien, FoV 1x1º,~2000 pointings, ugriz&H
• RoboTel (C. Armazones): 80cm, Cassegrain, 33.5 arcmin, ~7500 pts., full Strömgren and H set (plus UBVRI, ugriz).
• RoboTel (C. Armazones): 80cm, Cassegrain, 33.5 arcmin, ~7500 pts., full Strömgren and H set (plus UBVRI, ugriz).
![Page 4: Getting Precise Stellar Parameters in PLATO’s first field](https://reader035.vdocuments.net/reader035/viewer/2022062516/56814a86550346895db798fc/html5/thumbnails/4.jpg)
Robotel
![Page 5: Getting Precise Stellar Parameters in PLATO’s first field](https://reader035.vdocuments.net/reader035/viewer/2022062516/56814a86550346895db798fc/html5/thumbnails/5.jpg)
NGC 891
LBT Mt.Graham5min, seeing 0.8“B-band
RoboTel in Potsdam20min, seeing 3.3“V-band
![Page 6: Getting Precise Stellar Parameters in PLATO’s first field](https://reader035.vdocuments.net/reader035/viewer/2022062516/56814a86550346895db798fc/html5/thumbnails/6.jpg)
Identical Instrument
on STELLA-1,1.2m, Izaña
• 40 sec, on 5.8.2010
• 1.3´´ seeing10´´
1´´
![Page 7: Getting Precise Stellar Parameters in PLATO’s first field](https://reader035.vdocuments.net/reader035/viewer/2022062516/56814a86550346895db798fc/html5/thumbnails/7.jpg)
Bochum-University/Antofagasta Observatory at base of
Cerro Armazones
~350 clear nights
~50% seeing < 1”
Image: R. Chini
![Page 8: Getting Precise Stellar Parameters in PLATO’s first field](https://reader035.vdocuments.net/reader035/viewer/2022062516/56814a86550346895db798fc/html5/thumbnails/8.jpg)
Strömgren indices
(b-y) for eff. Temperaturem1=(v-b)-(b-y) for line blanketingc1=(u-v)-(v-b) for Balmer discontinuity
For late-type (FGKM) stars (dwarfs), m1 is a good proxy for metallicity, c1 for log(g)
Holmberg et al., A&A 475, 519Ramirez & Melendez, ApJ 626, 446Árnadóttir et al., A&A 521, A40
The calibrations used for error analysis are from:
![Page 9: Getting Precise Stellar Parameters in PLATO’s first field](https://reader035.vdocuments.net/reader035/viewer/2022062516/56814a86550346895db798fc/html5/thumbnails/9.jpg)
3-year survey?•1300h/year h>30•85% clear nights•Moon: 3-5 days around full moon•Downtime <20% (STELLA)•Standards? (~20min/night)
h13902170
36517552535
72.0*83.0*75.085.0*90.0*85.0
*3*1300
11-17min/pointing
![Page 10: Getting Precise Stellar Parameters in PLATO’s first field](https://reader035.vdocuments.net/reader035/viewer/2022062516/56814a86550346895db798fc/html5/thumbnails/10.jpg)
Photometric precisionIncluding slewing/read-out overhead, effective exposure times in y are
•10.3-23.7 sec. (8 filters)•20.1-40.7 sec. (6 filters)•52.6-97.2 sec. (4 filters)
STELLA-1 (1.2m)!
translates to 13.3-15.8
ybv = 3.5-15 mmag,u = 8-30 mmag
![Page 11: Getting Precise Stellar Parameters in PLATO’s first field](https://reader035.vdocuments.net/reader035/viewer/2022062516/56814a86550346895db798fc/html5/thumbnails/11.jpg)
…but only in the standard system
Transformation to account for different filter curves (i, i) and atmospheric conditions (k’i, i)
std
mmstdinsmstd
bybyinsbystd
cXkybmm
Xkybyb
,1
1,1,1 ')(')()(
…determined by observation of standard fields, with errors k, , , . nightly
varies slowly
![Page 12: Getting Precise Stellar Parameters in PLATO’s first field](https://reader035.vdocuments.net/reader035/viewer/2022062516/56814a86550346895db798fc/html5/thumbnails/12.jpg)
Observe at high and low X
0.030.0150.009
0.0240.0120.007
0.220.05-
0.120.080.015
k’
c1m1(b-y)On STELLA-1, two observations in one night, each 20min at X=1.5 and X=1.05
…errors hold only for the standard field!
![Page 13: Getting Precise Stellar Parameters in PLATO’s first field](https://reader035.vdocuments.net/reader035/viewer/2022062516/56814a86550346895db798fc/html5/thumbnails/13.jpg)
Reddening?
Stromgren indices only in de-reddened form, but Plato field at moderate galactic latitude...
Use ß–index, independent of reddening (same ).According to Crawford (AJ 80, 955)
)1,1(7.211.1222.0)()( 2 cmOybybE std
…again one notch on your error budget
![Page 14: Getting Precise Stellar Parameters in PLATO’s first field](https://reader035.vdocuments.net/reader035/viewer/2022062516/56814a86550346895db798fc/html5/thumbnails/14.jpg)
Results
Error budget dominated by filter transformations (, ) because only two fields measured. Alleviated by slow variation in these coefficients. Redding only significant in (b-y)
![Page 15: Getting Precise Stellar Parameters in PLATO’s first field](https://reader035.vdocuments.net/reader035/viewer/2022062516/56814a86550346895db798fc/html5/thumbnails/15.jpg)
Teff (b-y)
,=0,inst=10mmag
std=11.7mmag
red=18.8mmag
Sample data from Olsen, A&AS 57, 443
![Page 16: Getting Precise Stellar Parameters in PLATO’s first field](https://reader035.vdocuments.net/reader035/viewer/2022062516/56814a86550346895db798fc/html5/thumbnails/16.jpg)
Metallicity (b-y,m1,c1)
,=0,inst=17.1mmag
std=19.6mmag
red=5.6mmag
Sample data from Olsen, A&AS 57, 443
![Page 17: Getting Precise Stellar Parameters in PLATO’s first field](https://reader035.vdocuments.net/reader035/viewer/2022062516/56814a86550346895db798fc/html5/thumbnails/17.jpg)
log(g)
,=0,inst=21.7mmag
std=39.2mmag
red=3.8mmag
Sample data from Olsen, A&AS 57, 443
![Page 18: Getting Precise Stellar Parameters in PLATO’s first field](https://reader035.vdocuments.net/reader035/viewer/2022062516/56814a86550346895db798fc/html5/thumbnails/18.jpg)
Conclusions
Extremely ambitious task.Success depends on good filter transformation.Are there enough standards (in the field)?log(g) at best to distinguish dwarfs and giants.Sacrifice filters/fields?