Spectral Monitoring of UXORs with Interference Filters

V. Strelnitski, L. Weiss,

M. Davidson, & G. Walker

Maria Mitchell Association

AAVSO Meeting, 10-17-08

V3798 Sgr

UXORsUXORs

Herbig AeBe stars Herbig AeBe stars

Deep irregular drops of brightnessDeep irregular drops of brightness

Small dust cloudlets [in a disk] ?Small dust cloudlets [in a disk] ?

RR Tau: Photometry and Spectroscopy

RR Tau, Spectra

Line Flux versus Continuum Brightness

V3798 Sgr

R.A.: 18 15 25.73

DEC: -19 39 15.1

(2000.0)

V3798 Sgr

“Hα” (6563Å) “Ri”

(6450Å)

A drop of theory…

Differential Photometry: S ≡ (adu)T / (adu)C

1. Emission line flux correlates with the observed continuum flux

S(Hα) = βγ * κS(Ri) ,

β ≡ [fT(6563) * ΔλT(Hα) / fT(6450) * ΔλT(Ri)] * [fC(6450) * ΔλC(Ri)] ] / [ fC(6563) * ΔλC(Hα)]

γ ≡ 1 – (Wa – We ) / ΔλT(Hα) κ = exp [τ(6450) - τ (6563)] = exp [0.0158 Δm(Ri)].

2. Emission line flux does not correlate with the dimming due to dust

S(Hα) = βγ′ * κS(Ri) + E / [ fC(6563)]*Δλ(Hα)] ,

γ′ ≡ 1 – Wa / ΔλT(Hα)

V3798 Sgr: S(Ri) versus Time

0

0.05

0.1

0.15

0.2

0.25

0.3

4580 4600 4620 4640 4660 4680 4700 4720

JD - 2450000

S(R

i)

Period 1

Period 2

R CrB

V3798 Sgr: S(Ri) versus Time

0

0.05

0.1

0.15

0.2

0.25

0.3

4580 4600 4620 4640 4660 4680 4700 4720

JD - 2450000

S(R

i)

Period 1

Period 2

Are UXORs intrinsically variable?

S(Hα) versus κS(Ri)

V3798 Sgr: S (Ha) vs kappa*S (Ri) for the period of dimmings

(JD 4615-4651)

y = 0.9564x + 0.0087

R2 = 0.9959

0.05

0.1

0.15

0.2

0.25

0.04 0.09 0.14 0.19 0.24

kappa*S (Ri)

S(H

a)

V3798 Sgr: S (Ha) vs kappa*S (Ri) for the period of high brightness

(JD 4652-4706)

y = 1.0473x - 0.0011

R2 = 0.9857

0.150.170.190.210.230.250.270.290.31

0.15 0.2 0.25 0.3

kappa*S (Ri)S

(Ha)

V3798 Sgr: Ri and Hα Emission

V3798 Sgr: The Ha Emission Light Curve[ E = S (Ha ) - 0.9564*kappa*S (Ri) ]

0

0.005

0.01

0.015

0.02

0.025

0.03

0.035

4580 4630 4680

JD - 2450000

E [

in u

nit

s o

f f_

C(5

63)]

*Δλ(

Hα

)]

V3798 Sgr: S(Ri) versus Time

0

0.05

0.1

0.15

0.2

0.25

0.3

4580 4600 4620 4640 4660 4680 4700 4720

JD - 2450000

S(R

i)

Period 1

Period 2

Period 1

Period 2

ConclusionsConclusions

Interference filter photometry of UXORs Interference filter photometry of UXORs allows for separation of emission line allows for separation of emission line variability from continuum variabilityvariability from continuum variability

V3798 Sgr is a new UXOR and it may be V3798 Sgr is a new UXOR and it may be intrinsicallyintrinsically variable variable

MMO starts an extensive program of MMO starts an extensive program of monitoring UXORs with interference monitoring UXORs with interference filtersfilters