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Nova Scorpii 2007 (V1280 Sco)  @psychohistorian.org

Nova Scorpii 2007 (V1280 Sco)

posted: 4289 days ago, on Monday, 2007 Feb 19 at 03:07
tags: astronomy, variable stars.

An IAU Circular on February 06 announced the discovery of Nova Scorpii 2007 which was around 10th magnitude when it was first seen by a Japanese astronomer, Yuji Nakamura. It was independently discovered by countryman Yukio Sakurai – who found it on images taken with a Fuji FinePix S2 digital camera and a Nikon 180-mm f/2.8 lens!

The nova is located at RA 16h 57m 41s, Dec. -32°20.5'. The photo above, taken 2007.02.19 at 03:30 SAST shows Scorpius, with Jupiter left of centre, rising over my neighbour's trees. The nova is clearly visible near the centre of the image, to the bottom-left of epsilon Scorpii. The highlighted block is shown below.

February 19, Monday morning

From this morning's observation, 2007 February 19.05, it is certainly brighter than V=5.0 (as the image above confirms; HR 6316 has V=5.0). Using HR 6143 (V=4.2; from AAVSO chart) as second comparison star, I estimate the nova at V=4.4 (the red dot in the light curve below).

February 21, Wednesday morning

After yesterday morning's cloud, I was keen to see what the nova was up to (arrowed in today's photo, below). Interestingly it has a reddish tinge, though not as prominent as nearby HR 6288 (V=5.5, B-V=+1.6).

From CBET No 852 I later learnt that Munari and colleagues carried out photometry of the nova on Feb 20.2, finding B=5.90, V=4.83 giving a vaguely reddish B-V = +1.07.

February 22, Thursday

On IAU Circular 8810, a second nova eruption in the Scorpion was announced. How about that! More details and images here.

February 23, Friday

Yesterday's cold front passed over leaving the skies beautifully clear this morning, and Nova Scorpii 20070 was still plainly visible.

I estimated its magnitude as V=5.1 (2007 Feb 23 @ 03:01 UT, using AAVSO chart 070217 and comparison stars 50 and 55; green dot in the light curve below).

Remarkably, it doesn't look so red this morning; I would estimate the B-V = +0.1. It certainly didn't look as red as HR 6288 nearby (see Wednesday's remarks).

February 23: IAU Circular announcement

IAUC 8812, issued yesterday by the Central Bureau for Astronomical Telegrams, briefly reports CCD photometry of V1280 Sco carried out on Feb 21.483 by J.D. West (Kansas, USA), who found V=4.730.01. I've indicated this measurement with a yellow dot on the light-curve below.

West also did near-infared photometry, finding H=2.870.06, showing the star to be very bright in the infra-red.

February 25, Sunday: Weather report

I'm holding thumbs that the cloudy weather this weekend will clear up and give open skies on Monday morning...

February 26, Monday

The skies were mostly clear this morning, and I could see V1280 still going strong at just a bit fainter than 5th magnitude.

February 27, Tuesday

V1280 seems happy at V=5.5 this morning (2007.02.27, 02:21 UT); with 11x80 binoculars I compared it to nearby HD 156098 (V=5.5) and HD 155450 (V=6.0).

Colour-wise, I estimate its B-V as redder than +0.3 but not as far as +0.8; I'd be happy with B-V=+0.6.

February 28, Wednesday

This morning (2007.02.28, 04:20 SAST), using 11x80 binocs, V1280 looked convincingly fainter than V=5.5 but not quite down to V=6.0.

Its fading in the infra-red too; on Feb 27.5 it was at H=3.79 (measured by J.D. West), a one-magnitude drop since Feb 21.5.

Light curve of V1280 Sco

The light curve below, compiled from IAU Circular data and recent AAVSO records, shows the sudden increase in brightness and on-going fading.

It is still brighter than 6th magnitude so remains a naked-eye object from dark skies, and easy in binoculars.

Spectroscopy of V1280 Sco

Spectroscopic observations on Feb 5.9 at Nishi-Harima Astronomical Observatory (reported on IAUC 8803, Feb 6) suggest that it is a classical nova caught near maximum light.

Follow-up spectroscopy, made on Feb. 14.86, shows a much bluer continuum than reported earlier. "The new spectra resemble the spectrum of an F-type star," IAU Circular 8807 reports. "Balmer lines (relatively weaker than in the Feb. 5 spectrum) show clear P-Cyg profiles (expansion velocity about 500 km/s), along with other weak lines."

Links

  1. V1280 at SIMBAD
  2. AAVSO variable star chart
  3. AAVSO page for Nova Sco 2007
  4. Nova Sco 2007 on APOD for Feb 19th

Updated

Feb 19 @16:14 Feb 19 @22:20 Feb 21 @22:50 Feb 22 @19:00 Feb 23 @07:12 Feb 23 @13:40 Feb 25 @22:20 Feb 27 @05:57 Feb 28 @07:29.

nothing more to see. please move along.


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