Large-amplitude variables in Gaia Data Release 2. Multi-band variability characterization. (arXiv:2009.07746v3 [astro-ph.SR] UPDATED)
<a href="http://arxiv.org/find/astro-ph/1/au:+Mowlavi_N/0/1/0/all/0/1">N. Mowlavi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Rimoldini_L/0/1/0/all/0/1">L. Rimoldini</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Evans_D/0/1/0/all/0/1">D. W. Evans</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Riello_M/0/1/0/all/0/1">M. Riello</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Angeli_F/0/1/0/all/0/1">F. De Angeli</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Palaversa_L/0/1/0/all/0/1">L. Palaversa</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Audard_M/0/1/0/all/0/1">M. Audard</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Eyer_L/0/1/0/all/0/1">L. Eyer</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Garcia_Lario_P/0/1/0/all/0/1">P. Garcia-Lario</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Gavras_P/0/1/0/all/0/1">P. Gavras</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Holl_B/0/1/0/all/0/1">B. Holl</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Fombelle_G/0/1/0/all/0/1">G. Jevardat de Fombelle</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lecoeur_Taibi_I/0/1/0/all/0/1">I. Lecœur-Taïbi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Nienartowicz_K/0/1/0/all/0/1">K. Nienartowicz</a>
The second data release (DR2) of Gaia provides mean photometry in three bands
for $sim$1.4 billion sources, but light curves and variability properties are
available for only $sim$0.5 million of them. Here, we provide a census of
large-amplitude variables with amplitudes larger than $sim$0.2 mag in the $G$
band for objects with mean brightnesses between 5.5 and 19 mag. To achieve
this, we rely on variability amplitude proxies in $G$, $G_{BP}$ and $G_{RP}$
computed from the uncertainties on the magnitudes published in DR2. We then
apply successive filters to identify two subsets containing respectively
sources with reliable mean $G_{BP}$ and $G_{RP}$ (for studies using colours)
and sources having compatible amplitude proxies in $G$, $G_{BP}$ and $G_{RP}$
(for multi-band variability studies). The full catalogue gathers $23,315,874$
large-amplitude variable candidates, and the two subsets with increased levels
of purity contain respectively $1,148,861$ and $618,966$ sources. A
multi-band variability analysis of the catalogue shows that different types of
variable stars can be globally categorized in four groups according to their
colour and blue-to-red amplitude ratios as determined from the $G$, $G_{BP}$
and $G_{RP}$ amplitude proxies. The catalogue constitutes the first census of
Gaia large-amplitude variable candidates, extracted from the public DR2
archive. The overview presented here illustrates the added-value of the mission
for multi-band variability studies even at this stage when epoch photometry is
not yet available for all sources. (Abridged abstract)
The second data release (DR2) of Gaia provides mean photometry in three bands
for $sim$1.4 billion sources, but light curves and variability properties are
available for only $sim$0.5 million of them. Here, we provide a census of
large-amplitude variables with amplitudes larger than $sim$0.2 mag in the $G$
band for objects with mean brightnesses between 5.5 and 19 mag. To achieve
this, we rely on variability amplitude proxies in $G$, $G_{BP}$ and $G_{RP}$
computed from the uncertainties on the magnitudes published in DR2. We then
apply successive filters to identify two subsets containing respectively
sources with reliable mean $G_{BP}$ and $G_{RP}$ (for studies using colours)
and sources having compatible amplitude proxies in $G$, $G_{BP}$ and $G_{RP}$
(for multi-band variability studies). The full catalogue gathers $23,315,874$
large-amplitude variable candidates, and the two subsets with increased levels
of purity contain respectively $1,148,861$ and $618,966$ sources. A
multi-band variability analysis of the catalogue shows that different types of
variable stars can be globally categorized in four groups according to their
colour and blue-to-red amplitude ratios as determined from the $G$, $G_{BP}$
and $G_{RP}$ amplitude proxies. The catalogue constitutes the first census of
Gaia large-amplitude variable candidates, extracted from the public DR2
archive. The overview presented here illustrates the added-value of the mission
for multi-band variability studies even at this stage when epoch photometry is
not yet available for all sources. (Abridged abstract)
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