The dependence of the characteristics of the brightness variability of Herbig Ae/Be stars on the orientation of their star-disk systems
Аннотация
We analyze the brightness variability of six Herbig Ae/Be stars: V1331 Cyg, LkHα198=V633 Cas, AS 442, XY Per, V517 Cyg, and WW Vul. The last two objects are UX Ori stars showing Algol-like brightness dips with amplitudes of % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVy0df9qqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaaGOmaKaaGm% acaciaaa3-xababGaGacaaW9VaiaiGaaaC-pyBaaWcbGaGacaaW9Va% iaiGaaak-lOlaaqcbasajaiGaaaC-dGccaaIWaGaeyOeI0IaaGOmam% acaciaaa3-xabajaaibGaGacaaW9VaiaiGaaaC-pyBaaWcbGaGacaa% W9VaiaiGaaak-lOlaaqcbasajaiGaaaC-dGccaaI1aaaaa!5AA5! $$2\mathop m\limits_. 0 - 2\mathop m\limits_. 5$$ . AS 442 and XY Per also exhibit brightness dips but with considerably lower amplitudes, % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVy0df9qqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaaGimamacac% iaaa3-xabajaaibGaGacaaW9VaiaiGaaaC-pyBaaWcbGaGacaaW9Va% iaiGaaak-lOlaaqcbasajaiGaaaC-dGccaaIZaGaeyOeI0IaaGimam% acaciaaa3-xabajaaibGaGacaaW9VaiaiGaaaC-pyBaaWcbGaGacaa% W9VaiaiGaaak-lOlaaqcbasajaiGaaaC-dGccaaI2aaaaa!5AA5! $$0\mathop m\limits_. 3 - 0\mathop m\limits_. 6$$ . On the contrary, such dips are not present in the light curves of V1331 Cyg and LkHα198, where stochastic variability with amplitudes of % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVy0df9qqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaaGimamacac% iaaa3-xabajaaibGaGacaaW9VaiaiGaaaC-pyBaaWcbGaGacaaW9Va% iaiGaaak-lOlaaqcbasajaiGaaaC-dGccaaIXaGaeyOeI0IaaGimam% acaciaaa3-xabajaaibGaGacaaW9VaiaiGaaaC-pyBaaWcbGaGacaa% W9VaiaiGaaak-lOlaaqcbasajaiGaaaC-dGccaaIYaaaaa!5A9F! $$0\mathop m\limits_. 1 - 0\mathop m\limits_. 2$$ on timescales of about a day can be seen. AS 442 and XY Per also show stochastic variability, but with lower amplitudes % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVy0df9qqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaaiikaiabgI% Ki7kaaicdadGaGacaaW9-fqaqcaasaiaiGaaaC-lacaciaaa3-d2ga% aSqaiaiGaaaC-lacaciaaGY-c6caaKqaGeqcaciaaa3-aOGaaGimai% aaiwdacaGGPaaaaa!4B48! $$( \approx 0\mathop m\limits_. 05)$$ . These different types of variability could be related to the orientations of the star-disk systems. We suggest that the brightness variations in young stars whose disks are viewed edge-on are mainly due to non-uniform absorption, whereas the character of the variability in stars with pole-on disks is determined by non-stationary accretion.