The first four years of GIARPS@TNG Observations

ABSTRACT

GIARPS (GIAno & haRPS) is an observing mode that allows having on the same focal station of the Telescopio Nazionale Galileo (TNG) both the high-resolution spectrographs, HARPS–N (visible, VIS) and GIANO–B (near-Infrared, NIR), working simultaneously. To date, GIARPS is the first and unique worldwide instrument providing cross-dispersed echelle spectroscopy at R= 50,000 in the NIR and 115,000 in the VIS over a wide spectral range (0.383−2.45 μm) in a single exposure. GIARPS is online since 2017 and it is used in a wide range of science cases, especially for the search of exoplanets around young and active stars and the characterization of their atmosphere. In the next future, it will be equipped with NIR absorbing cells to obtain high precision radial velocity (RV). Furthermore, a solar telescope (LOCNES, D=10 cm) will allow the use of GIANO-B to study NIR spectra of the Sun-like-a-star to have more hints on the influence of activity on RV and transmission spectroscopy.

1. GIARPS

GIARPS (Claudi et al 2017) is a TNG observing allowing the simultaneous use of the HARPS-N and GIANO-B spectrographs, exploiting a wide wavelength range (0.383 - 2.45 µm) with high-resolution (115,000 in the visible, 50,000 in the NIR) in a single exposure. GIARPS is the result of the refurbishment of GIANO from a fiber-fed spectrograph to GIANO-B directly fed by the same Nasmyth-B focus feeding HARPS-N, by means of a preslit.

The light coming from the Nasmyth-B focus meets a dichroic that reflects the visible toward HARPS-N and transmits the NIR to GIANO-B. The dichroic is mounted on a motorized slide to select the preferred observing mode.

GIANO-B dewar is rigidly connected to the fork of the TNG and does not add vibration modes to those generated by the telescope (jitter, tracking etc.). For the time being, GIARPS uses both the instruments for high precision radial velocity measurements exploiting the simultaneous reference technique with HARPS-N (Th–lamps) and GIANO-B (telluric lines) reaching in the NIR about 10 m\s for bright stars (H≤5 mag) and 70 m\s (H~9 mag). In future, it will be equipped with absorption cells (acethylene, ammonia and methane) to reach the better precision of 3 m/s.

2. SCIENTIFIC RESULTS

2.1 EXOPLANETARY SCIENCE

In the last few years, several works reported the contribution of GIARPS in the field of the search and characterization of extrasolar planets.

The simultaneous RV collection in the VIS and NIR band allows discriminating between planetary and stellar signals, being the latter wavelength-dependent.

Carleo et al. (2018) made use of several NIR RVs to rule-out the hot Jupiter around the 150 Myr old star BD+201790. With a similar method, in the framework of the GAPS2 program, Carleo et al. (2020) confirmed the presence of a hot Jupiter around the Hyades member HD285507 and demonstrated that the previously detected RV signal around AD Leo has stellar origin.

GIARPS also provides suitable data for the atmospheric characterization of exoplanets. Guilluy et al. (2020) performed high-resolution transmission spectroscopy of the transiting hot Jupiter HD189733b aiming to detect the absorption signal of the helium triplet at 1083.3 nm, an useful diagnostic for extended and escaping atmospheres. They confirmed the result by comparing the helium feature with the one of the Halpha in the VIS to evaluate the stellar activity impact on the planetary absorption.

Finally, Baratella et al. (2020) analysed a sample of intermediate-age stars (<700 Myr) to evaluate their atmospheric parameters and chemical composition both in VIS and NIR bands, by using a new spectroscopic method that uses titanium lines to overcome issues related to the young ages of the stars.

2.2 OTHER SCIENCE

Massi et al. (2019) combining GIARPS spectra with the high spatial resolution of GRAVITY, obtained a view of the innermost regions of circumstellar discs in YSOs modelling the accretion and ejection mechanisms.

The characterization of the star–disk interaction region of CTT in the Taurus-Auriga star-forming region is the main target of GHOsT project (Giannini et al 2019; Gangi et al. 2020). They analyzed the kinematic statistical properties of the [O I] 630 nm and H₂ 2.12 μm lines and their mutual relationship. The results suggest that molecular and neutral atomic emission in disk winds originate from regions that might overlap, with the survival of molecular winds in disks depending on the gas exposure to the star irradiation.

SPA (Origlia et al 2019) is an ongoing GIARPS large program with the aim to perform an age-resolved chemical map of the solar neighborhood and the Galactic thin disk. More than 500 stars, covering different distances, ages and evolutionary stages, will be observed. Frasca et al. (2019) for the ASCC 123 cluster, and D’Orazi et al. (2020) for Hyades and Praesepe derived the stellar parameters, extinction, radial, and projected rotational velocities, and chemical abundances. They found that Praesepe ([Fe/H]=+0.21±0.01 dex ) is more metal-rich than the Hyades (Δ[Fe/H]=+0.05±0.01 dex).

3. CONCLUSION

Since Fall 2017, GIARPS works routinely at the TNG. Thanks to its wide wavelength range it is unique in the northern hemisphere and up to the commissioning of NIRPS at the 3.6m ESO Telescope, the unique in this world. The search for extrasolar planets and the study of stellar populations are the major science cases. Furthermore, the range of GIARPS partially overlap the range of ARIEL suggesting a possible synergy with this space mission dedicated to the study of exoplanetary atmospheres.

REFERENCES

• Baratella et al. 2020, A&A, 640, A123
• Carleo et al. 2018, A&A, 613, A50
• Carleo et al. 2020, A&A 638, A5
• Claudi et al 2017, EPJP, 132, 364
• D'Orazi et al., 2020, A&A, 633, A38
• Frasca et al 2019,  A&A, 632, A16
• Gangi et al. 2020, A&A, 634, A32
• Giannini et al., 2019, A&A, 631, A44
• Guilluy et al. 2020, A&A, 639, A49
• Massi et al. 2019 in “JET Simulations, Experiments, and Theory: Ten Years After JETSET. What Is Next?” Ed. C. Sauty, p.133, Doi: K55-7873
• Origlia et al., 2019, A&A, 629, A117