Scans and Narrow-Band Photometry of Late-Type Stars in the One-Micron Region

AbstractA summary is given of the molecular bands occurring in the near-infrared spectra of cool stars, especially those having sufficient strength and freedom from contamination to be measurable by narrow-band photometry. In some cases useful indices of both temperature and luminosity can be obtained from such measurements. Several bands remain unidentified, including the 9910 Å band in late M dwarfs and at least nine bands in cool S stars.Three topics of a spectroscopic nature are discussed. (1) In Mira variables, grossly different spectral types are sometimes obtained from zero-volt and excited TiO bands of the same band system. (2) A few M stars have been found to show bands of’ both VO and CN at the same time. They may be the coolest known supergiants, although there remains some doubt as to their luminosities. (3) The first results are given from a program of measuring crude C12/C13 ratios from narrow-band photometry of sensitive points on the profile of the ∆υ = + 2 band sequence of CN. The observations require only a few minutes per star, and the method can be applied to G and K giants and supergiants as well as to carbon stars.

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Narrow-Band Photometry of Red Variables in Globular Clusters

International Astronomical Union Colloquium ◽

10.1017/s0252921100033480 ◽

1973 ◽

Vol 21 ◽

pp. 164-177

Author(s):

Robert F. Wing

Keyword(s):

Radial Velocity ◽

Globular Clusters ◽

Near Infrared ◽

Narrow Band ◽

Small Range ◽

Mira Variables ◽

Color System ◽

Red Giant ◽

M Stars

AbstractFourteen red variables in the southern globular clusters 47 Tuc, ω Cen, and NGC 362 have been observed on an eight-color system of narrow-band photometry in the near infrared. Temperatures are derived from blackbody fits to the calibrated fluxes, and spectral types are given for the M stars. The types observed for the three Mira variables in 47 Tuc range from M3.1 to M7.5; two small-range variables in the same cluster are later than M4. The variables in ω Cen are mostly earlier than K5, but spectra of types M3 and MO were also encountered among radial-velocity members. In both the metal-rich 47 Tuc and the metal-poor ω Cen, the relation between TiO band strength and temperature is approximately normal. Several of these stars fall well above or below the red giant branches of their clusters in diagrams of infrared magnitude against temperature. Comparisons are made with recent results obtained at Radcliffe Observatory on some of the same stars.

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Giant planets around AF and M stars

Proceedings of the International Astronomical Union ◽

10.1017/s1743921313007898 ◽

2013 ◽

Vol 8 (S299) ◽

pp. 64-65

Author(s):

Julien Rameau ◽

Gaël Chauvin ◽

Anne-Marie Lagrange ◽

Philippe Delorme ◽

Justine Lannier

Keyword(s):

Giant Planets ◽

Early Type ◽

Late Type ◽

M Dwarfs ◽

Low Mass Stars ◽

Planetary Mass ◽

Nearby Stars ◽

Low Mass ◽

M Stars ◽

The One

AbstractWe present the results of two three-year surveys of young and nearby stars to search for wide orbit giant planets. On the one hand, we focus on early-type and massive, namely β Pictoris analogs. On the other hand, we observe late type and very low mass stars, i.e., M dwarfs. We report individual detections of new planetary mass objects. According to our deep detection performances, we derive the observed frequency of giant planets between these two classes of parent stars. We find frequency between 6 to 12% but we are not able to assess a/no correlation with the host-mass.

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Multi-Wavelength High-Resolution Spectroscopy for Exoplanet Detection: Motivation, Instrumentation and First Results

Geosciences ◽

10.3390/geosciences8080289 ◽

2018 ◽

Vol 8 (8) ◽

pp. 289 ◽

Cited By ~ 1

Author(s):

Serena Benatti

Keyword(s):

High Resolution ◽

Near Infrared ◽

Giant Planet ◽

High Resolution Spectroscopy ◽

M Dwarfs ◽

Low Mass Stars ◽

First Results ◽

Multi Wavelength ◽

Low Mass ◽

Rocky Planets

Exoplanet research has shown an incessant growth since the first claim of a hot giant planet around a solar-like star in the mid-1990s. Today, the new facilities are working to spot the first habitable rocky planets around low-mass stars as a forerunner for the detection of the long-awaited Sun-Earth analog system. All the achievements in this field would not have been possible without the constant development of the technology and of new methods to detect more and more challenging planets. After the consolidation of a top-level instrumentation for high-resolution spectroscopy in the visible wavelength range, a huge effort is now dedicated to reaching the same precision and accuracy in the near-infrared. Actually, observations in this range present several advantages in the search for exoplanets around M dwarfs, known to be the most favorable targets to detect possible habitable planets. They are also characterized by intense stellar activity, which hampers planet detection, but its impact on the radial velocity modulation is mitigated in the infrared. Simultaneous observations in the visible and near-infrared ranges appear to be an even more powerful technique since they provide combined and complementary information, also useful for many other exoplanetary science cases.

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The Near Infrared FeH Lines as Indicators of Surface Gravity of M stars

Symposium - International Astronomical Union ◽

10.1017/s0074180900233597 ◽

1996 ◽

Vol 171 ◽

pp. 441-441

Author(s):

Ricardo Piorno Schiavon ◽

Beatriz Barbuy

Keyword(s):

Near Infrared ◽

Synthesis Method ◽

Population Synthesis ◽

Atmospheric Parameters ◽

M Dwarfs ◽

Synthetic Spectra ◽

Iron Hydride ◽

M Stars ◽

M Dwarf ◽

Ongoing Project

We compute synthetic spectra in the region around 1 μm, including the Wing-Ford band (WFB) of Iron Hydride (FeH) in the calculations. This band is known to be a good indicator of surface gravities of M stars. Employing Kurucz model atmospheres, we study the response of the intensity of the WFB to atmospheric parameters and check our results against observations of M dwarfs. This study is part of an ongoing project which aims to investigate the M dwarf-to-giant ratio in galaxies, through a population synthesis method, exploring a number of spectral indicators in the near infrared, such as the WFB, the NaI, CaII and CO near infrared features.

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SPIRou: NIR velocimetry and spectropolarimetry at the CFHT

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa2569 ◽

2020 ◽

Vol 498 (4) ◽

pp. 5684-5703 ◽

Cited By ~ 1

Author(s):

J-F Donati ◽

D Kouach ◽

C Moutou ◽

R Doyon ◽

X Delfosse ◽

...

Keyword(s):

Magnetic Fields ◽

Near Infrared ◽

Planetary Systems ◽

Young Stars ◽

Central Position ◽

M Dwarfs ◽

Testing Phase ◽

First Results ◽

New Generation ◽

Final Acceptance

ABSTRACT This paper presents an overview of SPIRou, the new-generation near-infrared spectropolarimeter/precision velocimeter recently installed on the 3.6-m Canada–France–Hawaii Telescope (CFHT). Starting from the two main science goals, i.e., the quest for planetary systems around nearby M dwarfs and the study of magnetized star/planet formation, we outline the instrument concept that was designed to efficiently address these forefront topics, and detail the in-lab and on-sky instrument performances measured throughout the intensive testing phase that SPIRou was submitted to before passing the final acceptance review in early 2019 and initiating science observations. With a central position among the newly started programmes, the SPIRou Legacy Survey (SLS) Large Programme was allocated 300 CFHT nights until at least mid 2022. We also briefly describe a few of the first results obtained in the various science topics that SPIRou started investigating, focusing in particular on planetary systems of nearby M dwarfs, transiting exoplanets and their atmospheres, magnetic fields of young stars, but also on alternate science goals like the atmospheres of M dwarfs and the Earth’s atmosphere. We finally conclude on the key role that SPIRou and the CFHT can play in coordination with forthcoming major facilities like the JWST, the ELTs, PLATO, and ARIEL over the decade.

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The CARMENES search for exoplanets around M dwarfs

Astronomy and Astrophysics ◽

10.1051/0004-6361/202039032 ◽

2020 ◽

Vol 642 ◽

pp. A227 ◽

Cited By ~ 1

Author(s):

C. Abia ◽

H. M. Tabernero ◽

S. A. Korotin ◽

D. Montes ◽

E. Marfil ◽

...

Keyword(s):

Near Infrared ◽

Signal To Noise Ratio ◽

Heavy Elements ◽

High Signal ◽

M Dwarfs ◽

Chemical Enrichment ◽

Near Infrared Spectra ◽

Theoretical Predictions ◽

History Of ◽

First Time

Due to their ubiquity and very long main-sequence lifetimes, abundance determinations in M dwarfs provide a powerful and alternative tool to GK dwarfs to study the formation and chemical enrichment history of our Galaxy. In this study, abundances of the neutron-capture elements Rb, Sr, and Zr are derived, for the first time, in a sample of nearby M dwarfs. We focus on stars in the metallicity range − 0.5 ≲ [Fe/H] ≲ +0.3, an interval poorly explored for Rb abundances in previous analyses. To do this we use high-resolution, high-signal-to-noise-ratio, optical and near-infrared spectra of 57 M dwarfs observed with CARMENES. The resulting [Sr/Fe] and [Zr/Fe] ratios for most M dwarfs are almost constant at about the solar value, and are identical to those found in GK dwarfs of the same metallicity. However, for Rb we find systematic underabundances ([Rb/Fe] < 0.0) by a factor two on average. Furthermore, a tendency is found for Rb – but not for other heavy elements (Sr, Zr) – to increase with increasing metallicity such that [Rb/Fe] ≳ 0.0 is attained at metallicities higher than solar. These are surprising results, never seen for any other heavy element, and are difficult to understand within the formulation of the s- and r-processes, both contributing sources to the Galactic Rb abundance. We discuss the reliability of these findings for Rb in terms of non-LTE (local thermodynamic equilibrium) effects, stellar activity, or an anomalous Rb abundance in the Solar System, but no explanation is found. We then interpret the full observed [Rb/Fe] versus [Fe/H] trend within the framework of theoretical predictions from state-of-the-art chemical evolution models for heavy elements, but a simple interpretation is not found either. In particular, the possible secondary behaviour of the [Rb/Fe] ratio at super-solar metallicities would require a much larger production of Rb than currently predicted in AGB stars through the s-process without overproducing Sr and Zr.

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Detection of OH at the evening terminator of the ultra-hot Jupiter WASP-76b

10.5194/epsc2021-222 ◽

2021 ◽

Author(s):

Rico Landman ◽

Alejandro Sánchez-López ◽

Paul Mollière ◽

Aurora Kesseli ◽

Amy Louca ◽

...

Keyword(s):

Near Infrared ◽

Signal To Noise Ratio ◽

Molecular Dissociation ◽

Molecular Absorption ◽

M Dwarfs ◽

Infrared Observations ◽

Hot Jupiters ◽

Near Infrared Spectra ◽

Generate Model ◽

Fast Spin

<p>Ultra-hot Jupiters have dayside temperatures similar to those of M-dwarfs. While molecular absorption from the hydroxyl radical (OH) is easily observed in near-infrared spectra of M-dwarfs, it is often not considered when studying the atmospheres of (ultra-)hot Jupiters. We use high-resolution spectroscopic near-infrared observations of a transit of WASP-76b obtained using CARMENES to assess the presence of OH. After validating the OH line list, we generate model transit spectra of WASP-76b with petitRADTRANS. The data are corrected for telluric contamination and cross-correlated with the model spectra. After combining all cross-correlation functions from the transit, a detection map is constructed. OH is detected in the atmosphere of WASP-76b with a signal-to-noise ratio of 6.1.&#160;From a Markov Chain Monte Carlo retrieval we obtain Kp=234 km/s and a blueshift of 13.9 km/s. Considering the fast spin-rotation of the planet, the OH signal is best explained with the signal mainly originating from the evening terminator and the presence of a strong day- to nightside wind. The signal appears to be broad, with a full width at half maximum of 16.2 km/s. The retrieval results in a weak constraint on the temperature of 2420-3150 K at the pressure of the OH signal. Our results demonstrate that OH is readily observable in the transit spectra of ultra-hot Jupiters. Studying this molecule can give new insights in the molecular dissociation processes in the atmospheres of such planets.</p>

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Exploring the stellar properties of M dwarfs with high-resolution spectroscopy from the optical to the near-infrared

Astronomy and Astrophysics ◽

10.1051/0004-6361/201833500 ◽

2018 ◽

Vol 620 ◽

pp. A180 ◽

Cited By ~ 14

Author(s):

A. S. Rajpurohit ◽

F. Allard ◽

S. Rajpurohit ◽

R. Sharma ◽

G. D. C. Teixeira ◽

...

Keyword(s):

High Resolution ◽

Near Infrared ◽

Spectral Synthesis ◽

Model Atmosphere ◽

High Resolution Spectroscopy ◽

Cloud Formation ◽

M Dwarfs ◽

Near Infrared Spectra ◽

The Galaxy ◽

Stellar Properties

Context. Being the most numerous and oldest stars in the galaxy, M dwarfs are objects of great interest for exoplanet searches. The presence of molecules in their atmosphere complicates our understanding of their atmospheric properties. But great advances have recently been made in the modeling of M dwarfs due to the revision of solar abundances. Aims. We aim to determine stellar parameters of M dwarfs using high resolution spectra (R ∼ 90 000) simultaneously in the visible and the near-infrared. The high resolution spectra and broad wavelength coverage provide an unique opportunity to understand the onset of dust and cloud formation at cool temperatures. Furthermore, this study will help in understanding the physical processes which occur in a cool atmospheres, particularly, the redistribution of energy from the optical to the near-infrared. Methods. The stellar parameters of M dwarfs in our sample have been determined by comparing the high resolution spectra both in the optical and in the near-infrared simultaneously observed by CARMENES with the synthetic spectra obtained from the BT-Settl model atmosphere. The detailed spectral synthesis of these observed spectra both in the optical and in the near-infrared helps to understand the missing continuum opacity. Results. For the first time, we derive fundamental stellar parameters of M dwarfs using the high resolution optical and near-infrared spectra simultaneously. We determine Teff, log g and [M/H] for 292 M dwarfs of spectral type M0 to M9, where the formation of dust and clouds are important. The derived Teff for the sample ranges from 2300 to 4000 K, values of log g ranges from 4.5 ≤ logg ≤ 5.5 and the resulting metallicity ranges from −0.5 ≤ [M/H] ≤ +0.5. We have also explored the possible differences in Teff, log g and [M/H] by comparing them with other studies of the same sample of M dwarfs.

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Two-Dimensional Spectral Classification of M Stars by Narrow-Band Photometry

Symposium - International Astronomical Union ◽

10.1017/s0074180900145978 ◽

1978 ◽

Vol 80 ◽

pp. 451-454

Author(s):

Robert F. Wing ◽

Nathaniel M. White

Keyword(s):

Spectroscopic Data ◽

Near Infrared ◽

Narrow Band ◽

Classification Criteria ◽

Spectral Classification ◽

Color System ◽

Effects Of Temperature ◽

M Stars ◽

Filter Photometry

To place a star on the HR diagram by means of spectroscopic data alone-i.e., without knowledge of the parallax-one must separate the spectroscopic effects of temperature and luminosity as cleanly as possible. Here we discuss the use of the red and near-infrared bands of TiO, VO, CN, and CaH as classification criteria for M stars. Our eight-color system of filter photometry (Wing 1971; White 1971a) has provided data on the first three molecules.

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CARMENES: Calar Alto high-Resolution search for M dwarfs with Exo-earths with Near-infrared and optical Echelle Spectrographs

Proceedings of the International Astronomical Union ◽

10.1017/s1743921311021156 ◽

2010 ◽

Vol 6 (S276) ◽

pp. 545-546 ◽

Cited By ~ 4

Author(s):

Andreas Quirrenbach ◽

Pedro J. Amado ◽

José A. Caballero ◽

Holger Mandel ◽

Reinhard Mundt ◽

...

Keyword(s):

High Resolution ◽

Radial Velocity ◽

Emission Line ◽

Wavelength Range ◽

Spectral Resolution ◽

Near Infrared ◽

M Dwarfs ◽

Simultaneous Emission ◽

M Stars ◽

Calar Alto

AbstractCARMENES (Calar Alto high-Resolution search for M dwarfs with Exo-earths with Near-infrared and optical Echelle Spectrographs) is a next-generation instrument for the 3.5 m telescope at the Calar Alto Observatory. CARMENES will conduct a five-year exoplanet survey targeting ~300 M stars. The CARMENES instrument consists of two separate fiber-fed spectrographs covering the wavelength range from 0.52 to 1.7 μm at a spectral resolution of R = 85,000. The spectrographs are housed in a temperature-stabilized environment in vacuum tanks, to enable a 1 m/s radial velocity precision employing a simultaneous emission-line calibration.

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