Measurements of Mass Flow in the Transition Region and Inner Corona

AbstractThe Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI) is a state-of-the-art, thermally stabilized, fiber-fed, high-resolution spectrograph for the Large Binocular Telescope (LBT) at Mt. Graham, Arizona. During daytime the instrument is fed with sunlight from the 10-millimeter aperture, fully automated, binocular Solar Disk-Integrated (SDI) telescope. The observed Sun-as-a-star spectra contain a multitude of photospheric and chromospheric spectral lines in the wavelength ranges 4200–4800 Å and 5300–6300 Å. One of the advantages of PEPSI is that solar spectra are recorded in the exactly same manner as nighttime targets. Thus, solar and stellar spectra can be directly compared. PEPSI/SDI recorded 116 Sun-as-a-star spectra during the 2017 August 21 solar eclipse. The observed maximum obscuration was 61.6%. The spectra were taken with a spectral resolution of ≈ 250000 and an exposure time of 0.3 s. The high-spectral resolution facilitates detecting subtle changes in the spectra while the Moon passes the solar disk. Sun-as-a-star spectra are affected by changing contributions due to limb darkening and solar differential rotation, and to a lesser extend by supergranular velocity pattern and the presence of active regions on the solar surface. The goal of this study is to investigate the temporal evolution of the chromospheric Na D doublet during the eclipse and to compare observations with synthetic line profiles computed with the state-of-the-art Bifrost code.

Download Full-text

bHROS high spectral resolution observations of PN forbidden and recombination line profiles

Proceedings of the International Astronomical Union ◽

10.1017/s1743921306003279 ◽

2006 ◽

Vol 2 (S234) ◽

pp. 367 ◽

Cited By ~ 3

Author(s):

M. J. Barlow ◽

A. S. Hales ◽

P. J. Storey ◽

X.-W. Liu ◽

Y. G. Tsamis ◽

...

Keyword(s):

Spectral Resolution ◽

High Spectral Resolution ◽

Line Profiles ◽

Recombination Line

Download Full-text

A Discussion on solar studies with special reference to space observations - The structure of the chromosphere-corona transition region from limb and disk intensities

Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences ◽

10.1098/rsta.1971.0063 ◽

1971 ◽

Vol 270 (1202) ◽

pp. 81-98 ◽

Cited By ~ 43

Keyword(s):

Low Temperature ◽

Special Reference ◽

Transition Region ◽

Solar Disk ◽

Solar Limb ◽

Hydrostatic Equilibrium ◽

Temperature Gradients ◽

Emission Lines ◽

Atomic Data ◽

Absolute Intensities

During a racket flight in April 1969, spectra were obtained of a region of the solar disk and at the solar limb. The absolute disk intensities derived from these data have been used to compute models of the transition region, making the assumptions that the relative abundances of different elements remain constant throughout the atmosphere, and that the electron pressure varies according to the equation of hydrostatic equilibrium. The models obtained are characterized by very steep temperature gradients. The relative intensities of emission lines in the disk and limb spectra have enabled the height of the emitting regions to be determined independently of the above assumptions, and independently of atomic data and absolute intensities. A comparison is made of the structure found by the two methods, and within the accuracy of the present data these are consistent. Emission from low temperature ( ~ 10 4 K) material is observed from heights up to 10 4 km above the transition region, and this probably originates in spicules.

Download Full-text

High spectral resolution line profiles and images of comet Halley

Advances in Space Research ◽

10.1016/0273-1177(85)90097-3 ◽

1985 ◽

Vol 5 (12) ◽

pp. 279-282 ◽

Cited By ~ 10

Author(s):

F.L. Roesler ◽

F. Scherb ◽

K. Magee ◽

J. Harlander ◽

R.J. Reynolds ◽

...

Keyword(s):

Spectral Resolution ◽

High Spectral Resolution ◽

Line Profiles ◽

Comet Halley

Download Full-text

H2 2.12 μm Spectroscopy and Imaging of HH Objects

International Astronomical Union Colloquium ◽

10.1017/s0252921100023927 ◽

1989 ◽

Vol 120 ◽

pp. 302-302

Author(s):

H. Zinnecker ◽

R. Mundt ◽

A. Moneti ◽

T.R. Geballe ◽

W.J. Zealey

Keyword(s):

Spectral Resolution ◽

High Spatial Resolution ◽

Preliminary Test ◽

High Spectral Resolution ◽

Line Of Sight ◽

Line Profiles ◽

Ir Camera ◽

Fabry Perot ◽

Hh Objects ◽

Hh Object

We have obtained high spectral resolution observations of a number of Herbig-Haro (HH) objects in the H2 v=1-0 S(1) line at 2.12μm. Objects observed included HH1/2, HH7-11, HH19, HH32A, HH40, and HH43, all associated with jet-like features or collimated optical outflows. Here we present velocity-resolved 2.12μm spectroscopy for HH40 (an HH-objects moving close to the line of sight) an for HH43B (an HH-object moving close to the plane of the sky). The full set of observations including interpretation is given in Zinnecker et al. (1989). We also present high spatial resolution H2 2.12μm images of HH40 and HH43. The 2.12μm H2 line profiles were obtained with the UKIRT infrared Fabry-Perot system (effective resolution 30-35 km/s) using a diaphragm of diameter 11” for both HH40 and HH43. The H2 images were obtained with the IR-array imager at the CTIO 1.5m telescope through a narrowband filter centred on the v=1-0 S(1) line. The IR-camera used had 58x62 pixels and a resolution of 0.9”/pixel. The exposure time was 2x120sec and 5x60sec for HH40 and HH43, respectively. The images are sky subtracted, but not fiat fielded, and should be viewed as preliminary test images.

Download Full-text

High-resolution emission line profiles in blue luminous stars

International Astronomical Union Colloquium ◽

10.1017/s0252921100004620 ◽

1989 ◽

Vol 113 ◽

pp. 279-280

Author(s):

Rino Bandiera ◽

Paola Focardi ◽

Aldo Altamore ◽

Corinne Rossi ◽

Otmar Stahl

Keyword(s):

High Resolution ◽

Emission Line ◽

High Velocity ◽

Large Scale ◽

Velocity Fields ◽

Emission Lines ◽

Line Profiles ◽

High Luminosity ◽

Stellar Envelopes ◽

Η Car

Emission lines are often observed in high luminosity stars and provide evidence of the presence of extended stellar envelopes. Ha is the most frequently observed across the H-R diagram, but lines of Hel or Fell are also found in emission in these stars. They could be used as diagnostics of the structure of their outer atmospheres and winds. High resolution (1/dl ~ 105) high S/N profiles of Ha and Hel 5876 in the galactic LBVs η Car, AG and HR Car, and in the LMC star S22 have been obtained with the ESO CAT-CES during 1984-87, and are described in Figs.1-5. We find that these stars show a large variety of profiles with narrow and broad emissions, wide or multiple blue-shifted absorptions. The profiles are largely variable. Once, a kind of inverse P Cyg profile was observed in HR Car (Fig.4). These results indicate the presence of large scale phenomena and high velocity fields which are dramatically variable in time. Continuous HIRES monitoring of these stars is urgently needed.

Download Full-text

Herschel/HIFI observations of molecular lines from young planetary nebulae

Proceedings of the International Astronomical Union ◽

10.1017/s1743921312011222 ◽

2011 ◽

Vol 7 (S283) ◽

pp. 320-321

Author(s):

Valentín Bujarrabal ◽

Miguel Santander-García ◽

Javier Alcolea ◽

Rebeca Soria ◽

Keyword(s):

Spectral Resolution ◽

High Velocity ◽

Planetary Nebulae ◽

High Spectral Resolution ◽

Radiative Cooling ◽

Line Profiles ◽

Bipolar Outflows ◽

Molecular Lines ◽

Dense Flows

AbstractWe present results from systematic Herschel/HIFI observations of molecular lines in the FIR/sub-mm from young planetary nebulae. The high spectral resolution provided by the hetorodyne spectrometer HIFI allows properly studying the line profiles, whose structure corresponds to the various kinematics of the most massive nebular components, including fast bipolar outflows and slow shells. In particular, we have studied the excitation properties of the high-velocity (dense) flows. In some cases we find typical temperatures of the fast gas over 100-200 K, though in others it remains cool, ≲30K. We argue that the thermodynamics of the molecule-rich bipolar outflows is driven by fast radiative cooling, after the passage of the shock that accelerated it.

Download Full-text

Probing the atmosphere of HD189733b with the Na i and K i lines

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa2435 ◽

2020 ◽

Vol 498 (1) ◽

pp. 1023-1033

Author(s):

E Keles ◽

D Kitzmann ◽

M Mallonn ◽

X Alexoudi ◽

L Fossati ◽

...

Keyword(s):

High Resolution ◽

High Altitude ◽

Spectral Resolution ◽

Absorption Lines ◽

High Spectral Resolution ◽

Transmission Spectra ◽

Line Profiles ◽

Line Broadening ◽

Atmospheric Processes ◽

Hot Jupiters

ABSTRACT High spectral resolution transmission spectroscopy is a powerful tool to characterize exoplanet atmospheres. Especially for hot Jupiters, this technique is highly relevant, due to their high-altitude absorption, e.g. from resonant sodium (Na i) and potassium (K i) lines. We resolve the atmospheric K i absorption on HD189733b with the aim to compare the resolved K i line and previously obtained high-resolution Na i-D line observations with synthetic transmission spectra. The line profiles suggest atmospheric processes leading to a line broadening of the order of ∼10 km/s for the Na i-D lines and only a few km/s for the K i line. The investigation hints that either the atmosphere of HD189733b lacks a significant amount of K i or the alkali lines probe different atmospheric regions with different temperature, which could explain the differences we see in the resolved absorption lines.

Download Full-text

Observations of Bipolar Mass Flow from Symbiotic Stars

International Astronomical Union Colloquium ◽

10.1017/s0252921100103197 ◽

1988 ◽

Vol 103 ◽

pp. 85-88

Author(s):

J. Solf

Keyword(s):

Accretion Disk ◽

Mass Flow ◽

Spectral Resolution ◽

High Velocity ◽

Binary Star ◽

High Spectral Resolution ◽

Symbiotic Stars ◽

Late Type ◽

Spectroscopic Observations ◽

Type Giant

AbstractSpectroscopic observations of high spatial and high spectral resolution indicate that mass flow from symbiotic stars generally exhibits a bipolar pattern. Besides the polar features moving at velocities up to several 100 km/s, equatorial structures of much lower expansion rate are present in some cases. Mostly, the high-velocity components appear to be highly collimated and hence can be considered as “jets”. The jets probably originate from an accretion disk within a binary star where mass from a late-type giant is accreted by a compact companion.

Download Full-text

Nebula around R Corona Borealis

Proceedings of the International Astronomical Union ◽

10.1017/s1743921312012008 ◽

2011 ◽

Vol 7 (S283) ◽

pp. 476-477 ◽

Cited By ~ 1

Author(s):

N. Kameswara Rao ◽

David L. Lambert

Keyword(s):

Electron Density ◽

Spectral Resolution ◽

General Characteristic ◽

Emission Lines ◽

High Spectral Resolution ◽

Low Density ◽

Deep Minimum ◽

Physical Conditions ◽

Double Peaks ◽

R Coronae Borealis Stars

AbstractThe star R Corona Borealis (R CrB) shows forbidden lines of [O II], [N II], and [S II] during the deep minimum when the star is fainter by about 8 to 9 magnitudes from normal brightness, suggesting the presence of nebular material around it. We present low and high spectral resolution observations of these lines during the ongoing deep minimum of R CrB, which started in July 2007. These emission lines show double peaks with a separation of about 170 km/s. The line ratios of [S II] and [O II] suggest an electron density of about 100 cm−3. We discuss the physical conditions and possible origins of this low density gas. These forbidden lines have also been seen in other R Coronae Borealis stars during their deep light minima and this is a general characteristic of these stars, which might have some relevance to their origins.

Download Full-text