WOCS Variability:Monitoring NGC6939

WOCS Variability:Monitoring NGC6939

S. Kafka (IUB)

D. Gibbs II (Univ. of Wyoming)

A. Henden (US Naval Obs.) R.K.Honeycutt (IUB)

S. Kafka (IUB)

D. Gibbs II (Univ. of Wyoming)

A. Henden (US Naval Obs.) R.K.Honeycutt (IUB)

BGSU, April 3, 2004

Age Reddening Metallicity Abundances Astrometric info Variability

http://www.astro.ufl.edu/~ata/wocs/

Age Reddening Metallicity Abundances Astrometric info Variability

http://www.astro.ufl.edu/~ata/wocs/

WIYN Open Cluster Study

Establish a standard database of open clusters

Our motivation:Cataclysmic Variables

Interacting binaries

WD accretes H-rich material from its low-mass, Roche-lobe filling companion

Unique natural laboratories for studying

Accretion Physics

Classical Novae

SNe Ia progenitors ?

Why Open Clusters?

Bonus: age, distance,

metallicity

Not many CVs known in

globular/open clusters

Only 3 CVs known in all

open clusters!

NGC 6939 Age = 1.6 ± 0.3 Gyr

0.29 < E(B-V) < 0.41

12.21 < m-M < 12.39 (Rosvick & Balam

2002)

[Fe/H] = -0.14±0.13(Friel et al 2002)

Variability study : 6 vars

(Robb & Cardinal 1998)

Credit: J. Burkle, D. Gibbs, D. Hoffmann, S. Kafka,WIYN 0.9m, IU REU 2003

Data

Telescope Dates of Obs.(2003)

Filter # obs

WIYN 0.91m 31 March – 14 Sept

R 174

USNOFS 1.3m

07 April – 16 Jun R 120

WIYN 0.91m 13 Jul BVI 3

USNOFS 1m April/June BVRI 16

NGC 6939USNOFS 1.3m

R- filter

NGC 6939WIYN 0.9m

E

N

Strengths Limitations

DAOPHOT/APPhot

( Stetson, 1987 PASP, v 99, p. 191-222)

Aperture/PSF photometry for every star in the image

Not optimized for variability studies

ASTROVAR(Honeycutt, R.K, 1992, PASP, 104,

435-440)

Incomplete ensemble photometry Error analysis & graphics tools Periodogram and light curve folding interface

Requires magnitudes as input

Data Reduction

CMDV R

B-V V-R

Results

R

R

R

R

Phase Phase

0 0.5 1 1.5 0 0.5 1 1.5 0 0.5 1 1.5 0 0.5 1 1.5

P=0.3548d P=0.4511d P=0.2419d P=0.2946d

P=0.3601d P=0.2951d P=0.11142d P=0.3379d

Results

R

R

Phase

JD - 2452700

V

B-V

s33s28

V467Cep

V470Cep V10

V466CepV2

V7 V1, V8

V3

V4V9

V6V5

P=0.5668d P=1.143d

P>95d

Oddities

NGC 6939USNOFS 1.3m

R- filter

µD

e

µRA

V4

V9

s28

V470 Cep

V8

NGC 6939

Oddities

Glushkova & Rastorguev 1991Monet et al. 2003 (USNO-B)

Conclusions:

Conclusions: No CVs found in the cluster

Cluster depleted of faint variables???

Future work: X-rays? More data!

More Clusters!

Kafka et al, 2004, AJ, 127, 1622