A proper motion study of the Lupus clouds using VO tools

(a collaboration with the SVO)

Francisco Jiménez Esteban (CAB & SVO)Belén López Martí (CAB) & Enrique Solano (CAB & SVO)

Gaia: II Reunión Científica de la REG, Santillana del Mar, September 2011

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The Lupus clouds

One of the nearest low-mass star forming regions

d=140-220 pc

age<5 Myr

Star-count map by

Cambrésy et al. (1999)

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The Lupus cloudsWithin or near the Gould Belt

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The Lupus cloudsThe stellar & substellar population: Most recent results

A large increase of the stellar and substellar population(but few spectra so far)

• Comerón (2008):

– Review of previous results.

– Lists 74 known members of Lup 1, 2, 3 & 4

• Merín et al. (2008):

– Spitzer c2d census of 159 PMS stars & candidates in Lup 1, 3 & 4

– Mostly objects with disks and/or envelopes

• Comerón et al. (2009):

– ~130 new cool, ~without envelope or disk, very low-mass members in Lup 1, 3 & 4.

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Proper motions of Lupus members

• Sample: Compilation from Comerón (2008), Merín et al. (2008) & Comerón et al. (2009) 331 objects

• Method:– Multiple Cone Search using TOPCAT– Matching radius: 2– Astrometric catalogues: USNO-B1, SSS, PPMX and UCAC3– Purge resulting catalog using UCAC3 information:

• Errors != 0• Useful observations >3

Final sample: 178 objects

Goal: To check membership of proposed Lupus candidate members

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Proper motions of Lupus members

Two kinematic groups!

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Proper motions of Lupus membersLupus 1:The two groups have different

spatial distributions and proper motion directions.

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Proper motions of Lupus membersLupus 3:The two groups have different

spatial distributions and proper motion directions.

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Proper motions of Lupus membersLupus 4:The two groups have different

proper motion directions.

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Proper motions of Lupus members

Group B is formed mostly by diskless stars, while Group A contains sources with and without disks.

Group B, as a whole, represent a later evolutionary stage than Group A.

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Proper motions of Lupus members

The Group B sources tend to be brighter and redder than the Group A sources.

Their infrared colours are consistent with reddened background giants

(but also with reddened late K and early M-type stars).

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Proper motions of Lupus membersComparison with Gould Belt populations

ROSAT Gould Belt stars (Wichmann et al. 1997) Upper Scorpius members (Bouy & Martín 2009)

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Properties of Lupus kinematic membersGroup A sources with and without disks

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Properties of Lupus kinematic membersEffective temperature

No trend (better precision required)

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Properties of Lupus kinematic members

Physical parameters

No trend (better precision required)

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Conclusions

• We have found two distinct kinematic groups in our compiled catalog of Lupus candidate members.

• The properties of the Group B sources (lower proper motions, location outside the cloud cores, virtual lack of sources with disks, optical and near-infrared colours) suggest that they are a background population or mixture of populations unrelated to the Lupus clouds.

• Group A sources have properties consistent with them being a genuine population of the Lupus clouds. Their proper motions are also consistent with those of other Gould Belt populations.

• We find no correlations between the proper motions and the properties of the Group A sources. More accurate measurements are required (Gaia).

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More details in

López Martí et al., 2011, A&A, 529, A108

More details in

López Martí et al., 2011, A&A, 529, A108