Wind Episodes in BZ CamKent Honeycutt

Indiana University

COLLABORATORS:Stella Kafka, Spitzer

Jeff Robertson, ATUArne Henden, AAVSO

Daniel Proga, UNLV

Spectra from KPNO,CTIO,WIYN,MMT

BZ Cam (Nova-like CV)

Photo from Greiner et al. 2001

Surrounded by faint bow-shaped nebulae, likely related to the wind.

P = 221 mini < 40°

Wind features in BZ Cam spectra are known to be quite variable (e.g. Ringwald & Naylor 1998; Prinja et al. 2000), but the character of the changes remain poorly defined.

BZ Cam is part of program to study CV winds inthe optical: 9 spectral runs on BZ Cam, covering many orbits.

This is a preliminary analysis of the BZ Cam(and some related) spectra.

Optical Study of CV Winds, with emphasis on variability

• Survey of ~80 mostly northern NL CVs, V < 17.5– Obtain spectral sequences when found “active”– At least two time scales for variability are found:

• Active/Inactive; time scales of weeks/years?• Wind episodes lasting 20-90 min

– Episodes are mostly resolved using 3-5 min exps– mostly spectrally resolved at 3 Ang resolution– Episode properties similar from star-to-star, but some systematic

differences star-to-star• Duty cycle of episodes can differ greatly from star-to-star

– BZ Cam has very frequent episodes, but (in our preliminary analysis) its other episode properties appear similar to those of other CVs

BZ Cam Ephemeris • Good orbital ephemeris needed for two purposes:

– Correct RVs of wind features for orbital motion– Check for any orbital phase dependence of the wind

• Existing spectroscopic periods of 0.1535d (Lu & Hutchings 1985) and 0.1533d (Patterson et al. 1996) have accumulated too much phase error.

• Our spect. data: Sequences (averaging 3 hr in length) on 9 nights over 11 months 2005-06.

• Orbital RV analysis known to be difficult in BZ Cam: confirmed.– Different lines have differing RV curves– Only the em core of HeI 5876 gave good periodgram results– Still had significant gamma changes night-to-night: prewhitening

required.

Folded BZ Cam RV Curves for the emission core of HeI 5876

T0 = 2453654.008(2) + 0.15353(4)*E, for – to + crossing of gamma by emission core.K = 84(5) km s-1

Movie format for time-lapse images of the changes in 3 spectral lines

BZ Cam Spectral Sequence 17b

2005-Oct-11(UT)KPNO 2.1-m + GoldCam

3A resolution, 3 min exps40 exp sequence over ~2.6 hrs

(Note occasional redshifted emission in Hα

BZ Cam Spectral Sequence 18

2005-Oct-12(UT)KPNO 2.1-m + GoldCam

3A resolution, 3 min exps60 exp sequence over ~4.3 hrs

TT Ari Spectral Sequence 28

2005-Oct-27(UT)WIYN 3.5-m + Hydra/MOS3A resolution, 3 min exps

50 exp sequence over ~4.8 hr

(Note redshifted Hα emission up to 2000 km s-1)

HL Aqr Spectral Sequence 16

2005-Oct-27(UT)WIYN 3.5-m + Hydra/MOS3A resolution, 5 min exps

36 exp sequence over ~3.8 hrUSNO/FS 1-m Photometry

BZ Cam Spectral Sequence 22

2005 Feb-21(UT)WIYN 3.5-m + Hydra/MOS3A resolution, 5 min exps

42 exp sequence over ~5.2 hrs

(considerable clouds)

BZ Cam Spectral Sequence 20

2006-Jan-11(UT)KPNO 4-m + RC

3A resolution, 3 min exps70 exp sequence over ~2.6 hrs

QUALITATIVE SYSTEMATICS (dominant behaviors/trends, but not without exceptions)

• He I 5876 (triplet) and Hα have similar blue absorption velocities from wind

• He I 6678 (singlet) never has P Cygni profile• Typical abs profile starts broad and shallow, evolving to

more narrow abs, with lower velocity• Blue shifted emission is common, esp in Hα • Red shifted emission sometimes occurs in Hα, (This is

relatively rare in BZ Cam but is common in Q Cyg and is sometimes present in TT Ari (as seen in the movie), and in V795 Her, V592 Cas, and HL Aqr)

EXTRACTING PRELIMINARY QUANTITATIVE SYSTEMATICS

• Correct RVs for orbital motion• Measure strengths and velocities of line components vs time

– Fit multi-component line profiles• Advantage: provides parameters for shapes as well as EW and RV• Disadvantages:

– Must choose number of components– Correlations among parameters

– Measure EW and centroid RV for C.M rest frame window -750 to -2500 km s-1, for em and abs, using direct integration• Advantages: -- Fewest assumptions needed -- Errors easier• Disadvantages:

– No shape parameter – Central em line can contribute

• Both fits and integration measures avail: Will discuss only some of the direct integration results today.

Examples of Inactive and active (time scales of days/months) Sequences for BZ Cam

MMT 2006-Sep 17 (UT)[Inactive]

WIYN 2006-Feb21 (UT)[Active]

Two Examples of Isolated Wind Episodes in BZ Cam

KPNO 2.1-m 2005-Oct-11 (UT) KPNO 2.1-m 2005-Oct-12 (UT)

QUANTITATIVE SYSTEMATICS (dominant behaviors/trends, but not without exceptions)

• Isolated P Cygni abs events start simul. in Hα and He I, but events last significantly longer in He I.

• Velocity evolution is same (to within errors) in Hα and in He I blue abs, declining from -2000 to -1000 km s-1 during most isolated events (6 of 7 for BZ Cam)

• Hα blue emission begins after and peaks after blue absorption events. (Some anticorrelation expected due to EW technique in which both abs and em EWs are extracted from the same spectral window)

Orbital Phase Dependence of the EW of the blue shifted He I 5876 absorption in BZ Cam

Most of the variability at a given phase is due to episodes, but there does appear to be some orbital dependence as well.

Prinja, Knigge, Witherick, Long,Bammer 2004 reported similar results for V592 Cas, includingprogression of abs vel from morenegative to less negative during episodes.

Unsteady disk outflow in wind simulations of Proga, Stone, Drew1999.Time scales for filaments are similarto those seen observationally ~500 sHowever, inhomogeneities are mostlynear disk plane, at low velocities

Resonance line profiles computed as a function of orbital inclination. Proga, Kallman, Drew, Hartley 2002.

Nature of Wind and Wind Episodes

• Models of outflows due to radiation pressure are promising but may need to be customized for these kinds of spectra:– Non-resonance scattering– Time dependent line profiles

• Are episodes due to lifting (and fall-back) of random wind-driven filaments, or to ballistic-like events? Or from a combination of the two?

• Random wind-driven filaments will be different front/back while an M-dot initiated ejection event might affect both front and back.– The high vel red emission that sometimes appears must be (for low i systems)

the backside outflow. If we see both front and backside spectral signatures, are they correlated with each other? or correlated with M-dot?

– Provides leverage for distinguishing random filaments from ejection common to both front and back? Key may be continuum light from M-dot

• Correlation with continuum flickering implies initiation of an episode by M-dot.

Simultaneous photometry and spectroscopy

• 7 partially-successful attempts on 4 different systems; 3 are BZ Cam• Many (but not all) were compromised in various ways, such as wind being

weak or absent. But BZ Cam has large 0.4 mag flickering in 1 good phot/sp run.

KPNO 2.1-m spectra. Tenagra photometry. 2005-Oct-12 (UT)