1. EXOR optiCal-Infrared Systematic Monitoring
Exorcism at LBT
EXOR optiCal-Infrared Systematic Monitoring
Simone Antoniucci, Teresa Giannini,
D. Lorenzetti, U. Munari, G. Li Causi,
B. Nisini, A. Arkharov, V. Larionov, F. Vitali, A. Harutyunyan,
A. Di Paola, A. Giunta, F. Strafella, V. Testa
A presentation about our project about the monitoring and characterization of EXOr variables also based on LBT data, called exorcism. A project for which I am co-PI together with my colleague Teresa Giannini.
INAF OAR, INAF OAPd, INAF IAPS, Univ. of Salento, TNG FGG, Univ. of St. Petersburg, Pulkovo Obs.

2. LBT Users' Meeting 2017 - Firenze S. Antoniucci - EXorcism
Young Stellar Objects
T Tauri star ~106 yr
Mloss
disk
Macc
[OI]
[FeII] HI
UV exc
jet
Dullemond & Monnier 2010 CO
Hartmann+ 2016
Exors variables are basically a subclass of TTS, so we are talking about low-mass pms objects with an age of order 1-few Myr surrounded by an accretion disk. When we obs in the opt NIR (AS we do with LBT) we are actually obs the innermst part where accretion takes place, which has typical scales of 1 or fraction of au. The matter flows in through the disk, then in proximity of the star the strong stellar magnetic disrupts the disk and the matter follows the magnetic f lines and finally accretes onto the star. At the same time, mag field is also responsible for acceleration and collimation of part of the matter that is ejected away in form of jets/outflows, which are a efficient mech to remove excess ang mom from the system. The accretion is quantify though the fundamental parameter that is Macc, ejection through Mloss. We can get info on the various structures via spectral signatures such excess emission at UV for the accretion shock, or emission lines such HI to trace accretion columns, forbidden lines such OI and FeII for winds and jets and for example CO emission for inner gaseous disk.
LBT Users' Meeting Firenze S. Antoniucci - EXorcism

3. LBT Users' Meeting 2017 - Firenze S. Antoniucci - EXorcism
Accretion evolution
After main-accretion stars accrete at lower rates (T Tauri phase)
Some T Tauri show powerful intermittent accretion outbursts (FUor/EXor events).
Crucial stage for understanding how accretion halts (IMF) and how these events affect the protoplanetary disk
Is FUor/EXOr phase an evolutionary stage of all YSOs? Are there outbursts even in the embedded phase?
Assuming short outbursts of enhanced accretion can explain the luminosity problem (accreting YSOs are not as luminous as expected)
Hartmann 1998
A highly interesting aspect in YSOs is the evolution of the accretion rate.
After the intial embedded stage where we have the main acc, the objects become visible at optical wavelengths and continue to accrete at lower rates (TT phase). While varability is a defining featire of TTS, some objects display powerful outburst that are interpreted as phases of enhanced accretion, accretion events...
More pwerful and longer (Fuors) and shorter more moderate (Exors). In this scheme there is an evolutionary sequennce n which… howeber this is not clear.
Also important to investigate if similar outbursts are present at earliest stages...
LBT Users' Meeting Firenze S. Antoniucci - EXorcism

4. LBT Users' Meeting 2017 - Firenze S. Antoniucci - EXorcism
EXors and FUors V
Hartmann+ 2016
Kospal+ 2011
Miller+ 2011
How these outburst appear? Here are some light curves revealing the outbursts… As I said, Outbursting objects are divided in two main groups, with different characteristics: FU Ori stars show more powerful outbursts that lead to increase in mag of 4-7… While Fuors are once-in-a-lifetime events, exors allow us to observe recurrent outburst and try to characterize these events and try to understand what it the generating mechanism. ΔV
duration/recurrence
Macc
FUors
5-7 mag
tens of yrs/?
Msun/yr
EXors
3-4 mag
months/several years
Msun/yr
LBT Users' Meeting Firenze S. Antoniucci - EXorcism

5. LBT Users' Meeting 2017 - Firenze S. Antoniucci - EXorcism
EXors and FUors V
Hartmann+ 2016
Kospal+ 2011
Miller+ 2011
About exors there is still uncertainty… Characterisation and modeling of EXor young outbursting variables has suffered from lack of multi-band observations that monitor their photometric and spectroscopic variations
In this context we have started our exprcism projetc.
Only few EXors known (30), resemble T Tauri stars when quiescent
Lack of wide-band spectroscopic information (especially for quiescence)
Lack of quantitive comparisons between quiescence and outburst
Outburst mechanism not clarified yet: thermal/gravitational instability, triggering from companion? (Audard+ 2014, Vorobyov & Basu 2010)
LBT Users' Meeting Firenze S. Antoniucci - EXorcism

6. EXorcism Photometric monitoring (BVRI, JHK) Spectroscopic datasets
EXOR optiCal-Infrared Systematic Monitoring
Photometric monitoring (BVRI, JHK)
detect outbursts, monitor color variations (typical sampling 3-4 weeks)
NIR: AZT-24 Campo imperatore, La Silla/REMIR
Opt: Asiago 122cm-telescope, La Silla/ROSS2 + ancillary smaller facilities
In the beginning it was basically a monitoring photometric program...
More recently we added a spectroscopic part with the aim of building a complete optical/NIR library spectra of known EXOrs, indeed as i SAID INE OF THE MAIN LIMITATIONS... For this library we used MODS and LUCI...
Spectroscopic datasets
 build library of optical-to-near-IR quiescence spectra of known EXors
acquisition and monitoring of outburst spectra
quiescence-outburst comparison
LR: LBT/MODS (optical) , LBT/LUCI (near-IR) (R~1000)
HR: Asiago 182cm-telescope (optical, R~20000); TNG/GIANO (near-IR, R~50000)
LBT Users' Meeting Firenze S. Antoniucci - EXorcism

7. LBT Users' Meeting 2017 - Firenze S. Antoniucci - EXorcism
Backup/filler program since 2014 to build an EXor spectral library
MODS ( μm) + LUCI ( μm) longslit spectra (R~1000)
Considered sample ~ 30 objects
Library status: complete (optical+near-IR) quiescence spectra of 15 objects, with partial spectra for 5 sources
V1118 Ori and V2492 Cyg observed in quiescence and outburst!
Giannini+ 2016
Giannini+ in prep.
Filler programme that takes advantage of periods when the seeing conditions are not optimal, as the targets are relatively bright obejcts... QUIESCENCE LIBRARY. The setup is very simple: we cover with MODS and LUCI the spectrum from 0.3 to 2.4 microns. Te total sample considered so far consists of about 30 objects.... Completed for Partial for 5. During the last 3 years we had also the opportunity to observe 2 outbursts...
Examples of spectra where you can see spectral features… shape of continuum, presence and intensity of tracers… to eventually get info on parameters
V1184 Tau
V2492 Cyg
MODS
LUCI
LBT Users' Meeting Firenze S. Antoniucci - EXorcism

8. LBT Users' Meeting 2017 - Firenze S. Antoniucci - EXorcism
Work/Papers
LBT spectra enable quantitative analysis of the quiescent phase
Macc, fluxes and excitation of accretion/ejection/disk tracers, circumstellar gas parameters, ...
Determination of the “zero level” for the object accretion activity, fundamental for meaningful quantitative comparison with outbursts (constraints on models)
Recent Exorcism publications based on LBT data
Antoniucci, Arkharov, Di Paola A&A 565, L7 (V1180 Cas characterization)
Antoniucci, Nucita, Giannini A&A 584A, 21 (V1180 Cas X-ray vs opt-NIR)
Lorenzetti, Antoniucci, Giannini ApJ 802, 24 (V1118 Ori quiescence)
Giannini, Lorenzetti, Harutyunyan+ 2016a A&A 588A, 20 (V1184 Tau variability)
Giannini, Lorenzetti, Antoniucci+ 2016b ApJ 819, L5 (V1118 Ori outburst – paper I)
Giannini, Antoniucci, Lorenzetti ApJ 839, 112 (V1118 Ori outburst – paper II)
+ … 2 more currently in preparation
The main aim of the EXORCISM LBT spectra is to quantitatively characterize the EXOrs during their quiescnce. This basically means to derive the Macc, fluxes of the tracers of the various circumstellar structures etc. This is fundamental to determine the zeros of the obejct activity, which is extremely important to have a reference for the meaningful and accurate comparison with outburst spectra.
Our programme has been quite succesful so far in terms of papers produced, with 6 papers completed in the last 3 years and 2 more currently in preparation.
Use v1118 ori to illustrate a little bit more in detail the kind of analysis we perform on the spectra
LBT Users' Meeting Firenze S. Antoniucci - EXorcism

9. LBT Users' Meeting 2017 - Firenze S. Antoniucci - EXorcism
The case of V1118 Ori
As an example of the work based on LBT spectra I will illustatre in this second part the obsrevations of the EXOr V1118 Ori.
For this target we had already acquired quiescence spectra with LBT in 2014 when, after 10 yr, the outburst was detected in the NIR during our monitoring program EXORCISM (Giannini+ 2016). The outburst lasted about 1 year and we were able to follow it also with MODS and LUCI.
After 10 yr quiescence new major outburst in
Rapid increase, then stable for a few months (0.5 mag variations), then slow fading
Hint at outburst periodicity?
Monitored spectra (MODS+LUCI)
Giannini+ 2017
LBT Users' Meeting Firenze S. Antoniucci - EXorcism

10. LBT Users' Meeting 2017 - Firenze S. Antoniucci - EXorcism
V1118 Ori: LBT spectra
LUCI
MODS
quiescence
Multiple tracers (accretion/ejection/disk)
From quiescence to outburst:
Change of continuum shape (blueing)
Appearance/enhancement of many tracers (HI, HeI, CaII, FeI, NaI, CO)
quiescence
Giannini , 2017
LBT Users' Meeting Firenze S. Antoniucci - EXorcism

11. LBT Users' Meeting 2017 - Firenze S. Antoniucci - EXorcism
Mass accretion rate I
2) Macc from fit of UV excess + spectrum (method by Manara+ 2014, 2017; Alcalà+ 2014)  determine also star params, extinction
Alcalà+ 2014
Giannini+ 2017
LBT Users' Meeting Firenze S. Antoniucci - EXorcism

12. LBT Users' Meeting 2017 - Firenze S. Antoniucci - EXorcism
Mass accretion rate II
1) Macc from line fluxes via Lacc/Lline relationships (Alcalà+ 14)
quiescence
outburst
Lorenzetti+ 2015
Giannini+ 2017
LBT Users' Meeting Firenze S. Antoniucci - EXorcism

13. Mass accretion variation
Giannini+ 2017
For the first time evolution of Macc during outburst
<Macc, quiesc> 3.3  Msun/yr  <Macc,outb peak> 2.6  10-7 Msun/yr
Macc variation by factor ~102
LBT Users' Meeting Firenze S. Antoniucci - EXorcism

14. Gas properties: HI decrements
HI Balmer decrements compared with models by Kwan+ 2011
Outburst temperature in the range ~ K
According to Antoniucci the shape of the Balmer decrements is of type 2 in quiescence and type 4 in outburst; type 4 decrements are typical of high accretors.
Density enhancement by factor of 100, the same as the increase in mass accretion rate
LBT Users' Meeting Firenze S. Antoniucci - EXorcism

15. LBT Users' Meeting 2017 - Firenze S. Antoniucci - EXorcism
V1118 outburst params
Complementary HR spectra from ASIAGO and TNG/GIANO provide info on line profile variations
Comprehensive analysis of the outburst from quiescence to peak: accurate derivation of “Δparams”
LBT Users' Meeting Firenze S. Antoniucci - EXorcism

16. LBT Users' Meeting 2017 - Firenze S. Antoniucci - EXorcism
Recap and future
Exorcism project
Optical/NIR photometric monitoring + spectroscopic characterization of EXors
EXor library of spectra  characterization and determination of “zeroes” for the main parameters (Macc)
Fundamental for comparison quiescence vs outburst
What’s
Complete the spectral library
LSST will identify lots of EXor candidates (also in younger phases)  follow-up with LBT
High-resolution observations of inner regions of EXors for investigating triggering mechanism (for instance SHARK!... this afternoon)
New works:
Giannini+ submitted (V2492 Cyg outburst)
Antoniucci+ in prep. (Global view, general properties of EXors in quiescence)
LBT Users' Meeting Firenze S. Antoniucci - EXorcism

17. Thank You
A che tante facelle? (G. Leopardi)