The ASAS-SN Catalog of Variable Stars VIII: “Dipper” Stars in the Lupus Star-Forming Region. (arXiv:2005.14201v1 [astro-ph.SR])
<a href="http://arxiv.org/find/astro-ph/1/au:+Bredall_J/0/1/0/all/0/1">J. W. Bredall</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Shappee_B/0/1/0/all/0/1">B. J. Shappee</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Gaidos_E/0/1/0/all/0/1">E. Gaidos</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Jayasinghe_T/0/1/0/all/0/1">T. Jayasinghe</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Vallely_P/0/1/0/all/0/1">P. Vallely</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Stanek_K/0/1/0/all/0/1">K. Z. Stanek</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kochanek_C/0/1/0/all/0/1">C. S. Kochanek</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Gagne_J/0/1/0/all/0/1">J. Gagn&#xe9;</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hart_K/0/1/0/all/0/1">K. Hart</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Holoien_T/0/1/0/all/0/1">T. W.-S. Holoien</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Prieto_J/0/1/0/all/0/1">J. L. Prieto</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Saders_J/0/1/0/all/0/1">J. Van Saders</a>

Some young stellar objects such as T Tauri-like “dipper” stars vary due to
transient partial occultation by circumstellar dust, and observations of this
phenomenon inform us of conditions in the planet-forming zones close to these
stars. Although many dipper stars have been identified with space missions such
as $Kepler$/$K2$, ground-based telescopes offer longer term and
multi-wavelength perspectives. We identified 11 dipper stars in the Lupus star
forming region in data from the All-Sky Automated Survey for SuperNovae
(ASAS-SN), and further characterized these using observations by the Las
Cumbres Global Observatory Telescope (LCOGT) and the Transiting Exoplanet
Survey Satellite $TESS$, as well as archival data from other missions. Dipper
stars were identified from a catalog of nearby young stars and selected based
on the statistical significance, asymmetry, and quasi-periodicity or
aperiodicity of variability in their ASAS-SN light curves. All 11 stars lie
above or red-ward of the zero-age main sequence and have infrared excesses
indicating the presence of full circumstellar disks. We obtain
reddening-extinction relations for the variability of 7 stars using our
combined ASAS-SN-$TESS$ and LCOGT photometry. In all cases the slopes are below
the ISM value, suggesting larger grains, and we find a tentative relation
between the slope (grain size) and the $text{K}_text{s}-[22:mutext{m}]$
infrared color regarded as a proxy for disk evolutionary state.

Some young stellar objects such as T Tauri-like “dipper” stars vary due to
transient partial occultation by circumstellar dust, and observations of this
phenomenon inform us of conditions in the planet-forming zones close to these
stars. Although many dipper stars have been identified with space missions such
as $Kepler$/$K2$, ground-based telescopes offer longer term and
multi-wavelength perspectives. We identified 11 dipper stars in the Lupus star
forming region in data from the All-Sky Automated Survey for SuperNovae
(ASAS-SN), and further characterized these using observations by the Las
Cumbres Global Observatory Telescope (LCOGT) and the Transiting Exoplanet
Survey Satellite $TESS$, as well as archival data from other missions. Dipper
stars were identified from a catalog of nearby young stars and selected based
on the statistical significance, asymmetry, and quasi-periodicity or
aperiodicity of variability in their ASAS-SN light curves. All 11 stars lie
above or red-ward of the zero-age main sequence and have infrared excesses
indicating the presence of full circumstellar disks. We obtain
reddening-extinction relations for the variability of 7 stars using our
combined ASAS-SN-$TESS$ and LCOGT photometry. In all cases the slopes are below
the ISM value, suggesting larger grains, and we find a tentative relation
between the slope (grain size) and the $text{K}_text{s}-[22:mutext{m}]$
infrared color regarded as a proxy for disk evolutionary state.

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