INTEGRAL cataclysmic and symbiotic stars. R. Hudec, V. Šimon F. Munz, J. Š trobl , P. Kubánek , P. Sobotka, R. Urban. Astronomical Institute, Academy of Sciences 251 65 Ondrejov, Czech Republic & ISDC, Versoix, Switzerland IBWS, Oct 25-28, 2006. v. - PowerPoint PPT Presentation
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R. Hudec, R. Hudec, V. Šimon V. Šimon F. Munz, J. F. Munz, J. Š Š trobl trobl , P. , P. Kubánek Kubánek , P. Sobotka, R. , P. Sobotka, R. Urban Urban Astronomical Institute, Academy of Sciences Astronomical Institute, Academy of Sciences 251 65 Ondrejov, Czech Republic 251 65 Ondrejov, Czech Republic & & ISDC, Versoix, Switzerland ISDC, Versoix, Switzerland IBWS, Oct 25-28, 2006 IBWS, Oct 25-28, 2006 v INTEGRAL cataclysmic and INTEGRAL cataclysmic and symbiotic stars symbiotic stars
Transcript
R. Hudec, R. Hudec, V. ŠimonV. ŠimonF. Munz, J. F. Munz, J. ŠŠtrobltrobl, P. Kubánek, P. Kubánek, , P. Sobotka, R. UrbanP. Sobotka, R. Urban
Astronomical Institute, Academy of SciencesAstronomical Institute, Academy of Sciences251 65 Ondrejov, Czech Republic251 65 Ondrejov, Czech Republic
Impact region near the Impact region near the magnetic pole of the WDmagnetic pole of the WD (bremsstrahlung – hard (bremsstrahlung – hard X-rays)X-rays)
Magnetic CVsMagnetic CVs (polars)(polars)
cyclotron emission from cyclotron emission from accretion column (mainly accretion column (mainly optical and UV)optical and UV)
bremsstrahlung from bremsstrahlung from shocks above impact shocks above impact region on the WD (X-rays)region on the WD (X-rays)
AM Her AM Her ((kTkTbrembrem~31 keV) ~31 keV)
(Rothschild et (Rothschild et al. 1981)al. 1981)
ST LMi – orbital modulation ST LMi – orbital modulation in hard Xrays (1.9-8.5 keV)in hard Xrays (1.9-8.5 keV)((EXOSATEXOSAT))
AM Her – orbial modulationAM Her – orbial modulationtop – soft X-rays (40-120 A)top – soft X-rays (40-120 A)bottom- hard X-rays bottom- hard X-rays (1.9-8.5 keV) ((1.9-8.5 keV) (EXOSATEXOSAT))
Mason (1985)Mason (1985)
Heise et al. (1985)Heise et al. (1985)
hard X-ray sourceshard X-ray sources
IBISIBIS
Production of gamma-rays in CVsProduction of gamma-rays in CVs can can reach even TeV energiesreach even TeV energies Acceleration of particles by the rotating Acceleration of particles by the rotating magnetic fieldmagnetic field of the WD in of the WD in intermediate polars in the propeller regime – intermediate polars in the propeller regime – AE AqrAE Aqr – detected by – detected byground-based Cherenkov telescopes in the TeV passband ground-based Cherenkov telescopes in the TeV passband (e.g. (e.g. Meintjes et al. 1992Meintjes et al. 1992) ) __________________________________________________________________________________________________________________
TeV emission from the polar TeV emission from the polar AM HerAM Herdetected bydetected by ground-based Cherenkov ground-based Cherenkov telescopestelescopes (Bhat et al. 1991)(Bhat et al. 1991)
Domain of hard X-rays/soft gamma raysDomain of hard X-rays/soft gamma rayswas little exploited before INTEGRALwas little exploited before INTEGRAL
(a) (a) detection of detection of the populations the populations of CVs and of CVs and symbiotics with symbiotics with the hardest X-ray spectrathe hardest X-ray spectra
(b) simultaneous observations (b) simultaneous observations in the optical and hard X-ray in the optical and hard X-ray regionsregions
(c) long-term observations with (c) long-term observations with OMC – including a search for OMC – including a search for rapid variations in observing rapid variations in observing series during science window series during science window (OMC observations also for (OMC observations also for systems bellow the detectionsystems bellow the detection limit in hard X-rays)limit in hard X-rays)
IBIS – all obs.IBIS – all obs.
IBIS – CoreIBIS – Core ProgramProgram
Known CVsKnown CVs:: Catalog and Atlas of Cataclysmic Catalog and Atlas of Cataclysmic Variables Variables (Downes et al. 2001)(Downes et al. 2001)
TTotalotal exposure exposure timetimess of IBIS of IBIS
TTotalotal exposure exposure timetimess of IBIS of IBIS
The summary of CV observations/detections by The summary of CV observations/detections by INTEGRAL during the first 3 years of INTEGRALINTEGRAL during the first 3 years of INTEGRAL
In total, 19 CVs detected (surprise, more than expected, almost 1In total, 19 CVs detected (surprise, more than expected, almost 10% of 0% of INTEGRAL detections)INTEGRAL detections)
•15 seen by IBIS (Barlow et al., 2006) – correlation of IBIS data and 15 seen by IBIS (Barlow et al., 2006) – correlation of IBIS data and Downes CV catalogueDownes CV catalogue
•4 are CV candidates revealed by optical spectroscopy of IGR sources 4 are CV candidates revealed by optical spectroscopy of IGR sources (Masetti et al., 2006) – new CVs, not in Downes catalogue(Masetti et al., 2006) – new CVs, not in Downes catalogue
Barlow et al., MNRAS 2006. The Barlow et al., MNRAS 2006. The results of cross-correlation with Downes results of cross-correlation with Downes CV catalogueCV catalogue
Periods:Periods:
Vast majority Porb Vast majority Porb > 3 h, ie. above the period gap (only one < 3 h)> 3 h, ie. above the period gap (only one < 3 h)
5 long period systems with Porb > 7 h5 long period systems with Porb > 7 h
Variation:Variation:
No significant modulation has been found in the 20-30 keV light curves. No significant modulation has been found in the 20-30 keV light curves. The majority of the CVs displays persistent soft gamma ray fluxes with The majority of the CVs displays persistent soft gamma ray fluxes with exception of V1223 Sgr and SS Cygexception of V1223 Sgr and SS Cyg
Spectrum:Spectrum:
Similar in most cases, power law or thermal bremsstrahlung model , Similar in most cases, power law or thermal bremsstrahlung model ,
Compare well with previous high energy spectral fits (de Martino et al. Compare well with previous high energy spectral fits (de Martino et al. 2004, Suleimanov et al. 2005, Barlow et al. 2006)2004, Suleimanov et al. 2005, Barlow et al. 2006)
Mean: Mean: ~2.8, kT~20 keV~2.8, kT~20 keV
Some statisticsSome statisticsIntermediate polars – only ~2% of the catalogued CVs,but dominate Intermediate polars – only ~2% of the catalogued CVs,but dominate the group of CVs seen by IBISthe group of CVs seen by IBIS
More such detections and new identifications can be hence expectedMore such detections and new identifications can be hence expected
Many CVs covered by CP remain unobservable by IBIS, but new have Many CVs covered by CP remain unobservable by IBIS, but new have been discoveredbeen discovered
IBIS tends to detect IPs and asynchronous polars: in hard X-rays, IBIS tends to detect IPs and asynchronous polars: in hard X-rays, these objects seem to be more luminous (up to the factor of 10) than these objects seem to be more luminous (up to the factor of 10) than single synchronous polars single synchronous polars
Detection of CVs by IBIS (non-flarig state) typically requires Detection of CVs by IBIS (non-flarig state) typically requires 150-150-250 250 ksec or more, but some remained invisible even after 500 ksecksec or more, but some remained invisible even after 500 ksec
V1223 SgrV1223 Sgr
Intermediate polarIntermediate polar
Most significantly detected CV in the IBIS survey, with a significance of 38 Most significantly detected CV in the IBIS survey, with a significance of 38 sigma in the 20-40 keV final mosaicsigma in the 20-40 keV final mosaic
Orbital period: Orbital period: PPorborb = 3.37 h = 3.37 h (Osborne et al. 1985, Jablonski and Steiner 1987)(Osborne et al. 1985, Jablonski and Steiner 1987)Rotational period of the white dwarf: Rotational period of the white dwarf: PProtrot = 746 sec = 746 sec (Osborne et al. 1985)(Osborne et al. 1985)Beat period (combined effect of Beat period (combined effect of PPorborb and and PProtrot): ): PPbeatbeat = 794.3 sec = 794.3 sec (Steiner et al. 1981)(Steiner et al. 1981)
Prominent long-term brightness variations:Prominent long-term brightness variations:- outburst with a duration of ~6 hr and amplitude >1 mag - outburst with a duration of ~6 hr and amplitude >1 mag (van Amerongen & van Paradijs (van Amerongen & van Paradijs 1989)1989)- episodes of deep low state (decrease by several mgnitudes) - episodes of deep low state (decrease by several mgnitudes) (Garnavich and Szkody (Garnavich and Szkody 1988)1988)
Indications for flaring activity:Indications for flaring activity:
•Seen by IBIS (flare lasting for ~ 3.5 hrs Seen by IBIS (flare lasting for ~ 3.5 hrs
~ 3 times of average (Barlow et al., 2006)~ 3 times of average (Barlow et al., 2006)
•Seen by INTEGRAL OMC in optical one year later (MJD=53110, 53116) Seen by INTEGRAL OMC in optical one year later (MJD=53110, 53116) lasting for ~ 15 min and ~ 2.5 hrs (Simon et al., 2005)lasting for ~ 15 min and ~ 2.5 hrs (Simon et al., 2005)
•Seen in optical by groud-based instrument (duration 6-24 hrs), Seen in optical by groud-based instrument (duration 6-24 hrs), Amerrongen & van Paradijs (1989)Amerrongen & van Paradijs (1989)
Confirms the importance of OMC instrument onboard INTEGRAL: even Confirms the importance of OMC instrument onboard INTEGRAL: even with V lim mag 15, it can provide valuable optical simultaneous data to with V lim mag 15, it can provide valuable optical simultaneous data to gamma-ray observationsgamma-ray observations
Similar flares known also for another IPs in optical, but Similar flares known also for another IPs in optical, but not in soft gamma:not in soft gamma:
Example Example TV ColTV Col (Hudec et al., 2005), where 12 optical flares have been (Hudec et al., 2005), where 12 optical flares have been observed so far, five of them on archival plates from the Bamberg observed so far, five of them on archival plates from the Bamberg Observatory. Observatory. TV Col is an intermediate polar (IP) and the optical counterpart of the X-ray source 2A0526-328 (Cooke et al. 1978, Charles et al. 1979). This is the first cataclysmic variable (CV) discovered through its X-ray emission.
Physics of the outbursts in IPs:Physics of the outbursts in IPs:
•Disk instability orDisk instability or
•An increase in mass transfer from the secondaryAn increase in mass transfer from the secondary
::
FField of the intermediate polarield of the intermediate polar V1223 SgrV1223 Sgr. .
Co-addedCo-added frames from frames from IBISIBIS. . Start exp. JD 2452730.17Start exp. JD 2452730.17
SSize of the fieldize of the field:: 9.1 9.1oox7.1x7.1oo. . North is up, East to the left.North is up, East to the left.
15 – 25 keV15 – 25 keV 25 – 40 keV25 – 40 keV
40 – 60 keV40 – 60 keV
V1223 SgrV1223 Sgr
V1223 SgrV1223 SgrRelation between far X-ray Relation between far X-ray flux and optical magnitudeflux and optical magnitude
Relating processes in Relating processes in different regions:different regions:Disk Disk (optical)(optical)Impact region near magneticImpact region near magneticpole of white dwarf pole of white dwarf (X-ray)(X-ray)
Time evolution of the Time evolution of the VV band band magnitude and X-ray flux in magnitude and X-ray flux in the 15 – 60 keV passbandthe 15 – 60 keV passband
Relation between the Relation between the VV band magnitude band magnitude and X-ray flux in the and X-ray flux in the 15 – 60 keV passband15 – 60 keV passband
IBIS spectrum in the IBIS spectrum in the 15 – 60 keV region15 – 60 keV regionSpectral profile remains Spectral profile remains largely unchanged largely unchanged during shallow low stateduring shallow low state(~ 400 days)(~ 400 days)
V1223 SgrV1223 Sgr
Means forMeans foreach scienceeach sciencewindowwindow
INTEGRALINTEGRAL observations observations in lower than average in lower than average level of brightness – level of brightness – long-lasting and rather long-lasting and rather shallow low stateshallow low state
Fluctuations of brightnessFluctuations of brightnessfor JD < 2 452 250for JD < 2 452 250
Short low state (LS) inShort low state (LS) inJD 2 451 650JD 2 451 650
Long LS after JD 2 452 250Long LS after JD 2 452 250
Statistical Statistical distribution distribution of the optical of the optical brightnessbrightness
Shallow Shallow low statelow state
Peak of high statePeak of high state
Relation between mass transfer rate Relation between mass transfer rate and and V V band magnitude, assuming band magnitude, assuming the system parameters according to the system parameters according to Model A of Model A of Beuermann et al. (2004)Beuermann et al. (2004)
Disk may become thermally unstableDisk may become thermally unstablein shallow low state – this is not observedin shallow low state – this is not observed(irradiation of the disk by the X-rays (irradiation of the disk by the X-rays can occur)can occur)
Smoothed beat modulation in Smoothed beat modulation in folded OMC data (100 sec exp. only) folded OMC data (100 sec exp. only) (ephemeris of(ephemeris of Jablonski and Steiner Jablonski and Steiner (1987): (1987): PPbeat beat = 794.3 sec)= 794.3 sec)
V1223 SgrV1223 SgrSearch for rotational and beat Search for rotational and beat modulation in OMC datamodulation in OMC dataduring shallow low stateduring shallow low state
Beat modulation still dominates over Beat modulation still dominates over the rotational modulation (stream–disk the rotational modulation (stream–disk overflow still operates in the shallow overflow still operates in the shallow low state)low state)
Stream–disk overflow persists when Stream–disk overflow persists when mass transfer rate decreases ~3 timesmass transfer rate decreases ~3 times
PProtrot
PProtrot PPbeatbeat
PPbeatbeatAll OMC dataAll OMC data
OMC data between OMC data between JD 2 453 000 and JD 2 453 000 and JD 2 453 100JD 2 453 100
Time (days)Time (days)
OMC data (100 sec exp. only) OMC data (100 sec exp. only) Ephemeris ofEphemeris of Jablonski and Steiner (1987):Jablonski and Steiner (1987): PPorb orb = 3.37 hr= 3.37 hr
The profile and phasing of the optical modulation The profile and phasing of the optical modulation appears to be quite similar to that observed by appears to be quite similar to that observed by Jablonski and Steiner (1987) Jablonski and Steiner (1987) in the high statein the high state
Smooth curve: moving averagesSmooth curve: moving averagesObservations of all three time intervals follow the Observations of all three time intervals follow the modulation and possess the same mean level of modulation and possess the same mean level of brightnessbrightness
Scatter – rotational modulation of the WD contributesScatter – rotational modulation of the WD contributes
V1223 SgrV1223 SgrOrbital modulation V & gammaOrbital modulation V & gamma
OpticalOptical
15-40 keV15-40 keVFlat modulation in hard X-Flat modulation in hard X-rays rays
Possible dip at phase ~0.9 Possible dip at phase ~0.9 may be caused by a very may be caused by a very dense material pushed dense material pushed away from the orbital away from the orbital plane by the stream impactplane by the stream impact
Observable emission region Observable emission region does not vary through the does not vary through the orbital cycleorbital cycle
NNHH=0 atoms/cm=0 atoms/cm22
NNHH=10=102424 atoms/cm atoms/cm22
NNHH=5x10=5x102323 atoms/cm atoms/cm22
V 1432 AqlV 1432 AqlDesynchronized polar Desynchronized polar (e.g. Patterson (e.g. Patterson et al. 1995). et al. 1995). Orbital period (3.37 hr) Orbital period (3.37 hr) and the rotational period of the WD and the rotational period of the WD differ by ~0.3 percentdiffer by ~0.3 percent
FField of ield of VV1432 Aql1432 Aql. . Co-addedCo-added fully coded images fully coded images from from IBISIBIS: : JD 2 452 756. Integration time: 37 160JD 2 452 756. Integration time: 37 160 sec sec..SSize of the fieldize of the field:: 99oox7x7oo. North is up, East to the left.. North is up, East to the left.
15 – 40 keV15 – 40 keV 40 – 80 keV40 – 80 keV
Averaged OMC Averaged OMC light curvelight curve
FluxFlux ((1515 – – 4040 keVkeV)) = (8.8 +/- 0= (8.8 +/- 0..9) x 9) x 1010-4-4 photon photon//cmcm22//ss LL (15 – 40 keV) = 1.4 x 10 (15 – 40 keV) = 1.4 x 103232 erg/s erg/s
IBIS image of the fIBIS image of the field of the ield of the iintermediate ntermediate polarpolar VV24002400 OphOph and the symbiotic and the symbiotic (neutron star) system (neutron star) system V2116 OphV2116 Oph. . Co-addedCo-added fully coded images fully coded images from from IBISIBIS: : JD 2452733 + JD 2452920 + JD 2453054.JD 2452733 + JD 2452920 + JD 2453054.Integration time: 53 760Integration time: 53 760 sec sec. . SSize of fieldize of field:: 9.19.1oox7.1x7.1oo. North is up, East to the left.. North is up, East to the left.
V2400 OphV2400 Oph
Averaged OMC light curve Averaged OMC light curve
Diskless intermediate polarDiskless intermediate polarOrbital period: Orbital period: PPorborb = 3.4 hr = 3.4 hrRotational period of the WD: Rotational period of the WD: PProtrot = 927 sec = 927 secBeat period: Beat period: PPbeatbeat = 1003 sec = 1003 sec (Buckley et al. 1997)(Buckley et al. 1997)
15 – 40 keV15 – 40 keV
FluxFlux ((1515 –– 4040 keVkeV)) = (= (9.379.37 +/- +/- 1.141.14) x ) x 1010-4-4 photon photon//cmcm22//ss
((Ishida Ishida et al. et al. 19921992))
quiescencequiescence
outburstoutburst
Relation between Relation between profile of optical profile of optical and X-ray outburstand X-ray outburst
X-ray start can precede theX-ray start can precede theoptical start by up to 40 days optical start by up to 40 days (Binachini & Sabbadin 1985)(Binachini & Sabbadin 1985)Models: up to 80 – 120 daysModels: up to 80 – 120 days(Kim et al. 1992)(Kim et al. 1992)
((SSimon 200imon 20044))
GK PerGK Per
Intermediate polar, very long Intermediate polar, very long PPorborb=1.99 days =1.99 days (Crampton et al. 1986)(Crampton et al. 1986)Spin period of the white dwarf Spin period of the white dwarf PPspinspin==351351 sec sec (Watson et al. 1985)(Watson et al. 1985)
Exploded as a classical nova in 1901Exploded as a classical nova in 1901
Fluctuations by ~1 mag after return to quiescence, Fluctuations by ~1 mag after return to quiescence, later they developed into infrequent later they developed into infrequent dwarf nova-type dwarf nova-type outburstsoutbursts (Sabbadin & Bianchini 1983, Hudec 1981)(Sabbadin & Bianchini 1983, Hudec 1981)
X-ray (2.5 – 11 keV) spin modulation – X-ray (2.5 – 11 keV) spin modulation – 351 s (351 s (EXOSATEXOSAT) during optical outburst) during optical outburst(Watson (Watson et al. 19et al. 1985)85)
IBISIBISrangerange
IBIS IBIS (25–40 keV)(25–40 keV) image image of of GK PerGK Per ((Integr. time: 79 980Integr. time: 79 980 sec sec Co-added images: 19 March 2003, 27 – 29 July 2003. Co-added images: 19 March 2003, 27 – 29 July 2003. SSize of fieldize of field:: 4.14.1ooxx3.03.0oo. North is up, East to the left.. North is up, East to the left.
GK PerGK Per INTEGRALINTEGRAL
Quiescent X-ray spectrum Quiescent X-ray spectrum Parameters from Ishida et al. (1992)Parameters from Ishida et al. (1992)((kT kT = 32 keV, = 32 keV, NNH H = 10= 102222 cm cm-2-2, , norm. factor: norm. factor: 0.00390.0039+/-+/-0.00020.0002 photonphoton//cmcm22/s/s11//keVkeV))
IBISIBIS
IInterval between outburstsnterval between outbursts:: t = 973 t = 973 daysdaysIBIS obs.:IBIS obs.: start at ~4 start at ~422 percent of this interval (percent of this interval (measured measured since the previous outburst). since the previous outburst). Ishida’s et al. Ishida’s et al. reference spectrum:reference spectrum: t = 983t = 983 days (start days (start at at ~~2929 percent of this interval). percent of this interval).
AAmount of matter arriving to the WD and the parameters mount of matter arriving to the WD and the parameters of the X-ray emitting region on the WD remained almost of the X-ray emitting region on the WD remained almost the same during these phases of the quiescent intervals.the same during these phases of the quiescent intervals.
FluxFlux ((1515 –– 4040 keVkeV)) = (2.= (2.77 +/- +/- 1.1.2) x 2) x 1010-4-4 photon photon//cmcm22//s s LL (15 – 40 keV) = 4.6 x 10 (15 – 40 keV) = 4.6 x 103232 erg/s erg/s
IX VelIX Vel
Examples of OMC light curvesExamples of OMC light curvesNova-like CVNova-like CVINTEGRAL OMC – two intervals coveredINTEGRAL OMC – two intervals coveredRapid variations (flickering) superimposed onRapid variations (flickering) superimposed on the long-term changesthe long-term changes(a) Outburst (duration <14 days)(a) Outburst (duration <14 days)(b) Short episode of a low state(b) Short episode of a low state
Superposition of both events: Superposition of both events: the time scales of the decaying the time scales of the decaying and rising branches of both and rising branches of both events appear to be comparableevents appear to be comparable
RSRS OphOph Examples of OMC light curvesExamples of OMC light curves relatively bright symbiotic relatively bright symbiotic systemsystem
orbital period orbital period PPorborb=460=460 days days inclination angle 30inclination angle 30oo – – 4040oo
giant component underfilling its lobe giant component underfilling its lobe (Dobrzycka (Dobrzycka && Kenyon 1994) Kenyon 1994) white dwarf (WD)white dwarf (WD) – – recurrent novarecurrent nova ((five obfive observedserved explosions explosions)) (e.g. Warner 1995)(e.g. Warner 1995)
QQuiescent brightness uiescent brightness – – fluctuatfluctuationsions ((months and yearsmonths and years)) 11 11 – – 12 mag12 mag((VV)), sometimes , sometimes 1010 magmag((VV)) (e.g. Dobrzycka (e.g. Dobrzycka && Kenyon 1994, Oppenheimer and Mattei 1996) Kenyon 1994, Oppenheimer and Mattei 1996)
RRapid optical variationsapid optical variations – – time scale of tens of minutes, similar to those often seen in time scale of tens of minutes, similar to those often seen in short-period CVsshort-period CVs (e.g. Walker 1977, Dobrzycka et al. 1996)(e.g. Walker 1977, Dobrzycka et al. 1996)
WWZ WWZ indicatesindicates whether whether oorr not there is a periodic not there is a periodic fluctuation at a givenfluctuation at a given time time at a givenat a given frequencyfrequency ((method ofmethod of Foster 1996Foster 1996). ).
Symbiotic stars as Hard-X-ray emitters: RT Cru and CD -57 3057 identified with IGR sources
(Masetti et al., 2005)
Novae, some of which occur in symbiotic stars, play an important role in the chemical evolution of the Galaxy and the symbiotic stars themselves. A common feature of symbiotic recurrent novae (RNe) is rapid optical flickering. At least one symbiotic RN (T CrB) has also produced very hard X-ray emission. RT Cru produces optical flickering, has an optical spectrum like that of T CrB, and has recently been discovered by Integral to produce X-ray emission out to ~60 keV. X-ray observations of RT Cru from the Chandra and Swift satellites clearly shows both thermal and non-thermal X-ray emission. Absorption of soft X-rays that is variable on a time scale of months suggests occultation by the red giant. There are two possible models for RT Cru: a jet-producing system viewed nearly edge on, or a magnetic white dwarf viewed pole on.
More detailed More detailed and more precise and more precise observations by southern FRAM observations by southern FRAM and WATCHER robotic telescopesand WATCHER robotic telescopes (Kubanek et al.) (Kubanek et al.) is in progress is in progress
This one and the newly detected symbiotics with INTEGRAL - This one and the newly detected symbiotics with INTEGRAL - CD-CD-57 3057 (Masetti et al., 2005)57 3057 (Masetti et al., 2005) – are optically very bright stars – are optically very bright stars
